US3530552A - Extrusion device - Google Patents

Description

SP 29, 1970 G. H. CALDER 3,530,552

EXTRUS ION DEVICE Filed April 29, 1968 5 Sheets-Sheet 1 INVENTOR.

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"ATTORNEY n GLEN H. CMDER 5Pf 29, 11970 G. H. CALDER 3,530,552

EXTRUS ION DEVICE 5 Sheets-Sheet 2 Filed April 29, 1968 BY ff? ATTORNEY Sept 29, 1970 G. H. CALDER I 3,530,552

ExTRUs ION DEvIcE Filed April 29, 1968 5 Sheets-Sheet 5 7o l l@ |38 |66 Il |60 |70 |56 l. I- ||l FIG. 3 54 INVENTOR, GLEN H. CALDER ATTORNEY sept 292 1970 G. H. cALDER 3,530,552l

EXTRUS ION DEVI GE 202 noe l|44 HG. l2 62 54 42 I 1 l f l 202 I '..0 F|G.|4 62 54 42 1NVENTOR. GLEN H. CALDER 'dff# ATTORNEYl sept' 29, 1970 G. H. CALDER 3,530,552

EXTRUS ION DEVI GE Filed April 29, 1968 5 Sheets-Sheet 5 lag FIG. I6 2|o 212 o6 e2 54 INVENTOR. GLEN H. CALDER ATTORNEY United States Patent O 3,530,552 EXTRUSION DEVICE Glen H. Calder, R.F.D. Box 286A, Springville, Utah 84663 Filed Apr. 29, 1968, Ser. No. 725,005 Int. Cl. B28b 21/52 U.S. Cl. 25--32 13 Claims ABSTRACT OF THE DISCLOSURE An apparatus and method for extruding concrete and the like, the apparatus comprising a variable length telescopic frame supported upon front and rear sets of wheels and an extrusion chamber having an open trailing eluent end, the chamber being carried by one frame portion and provided with a laterally disposed iniiuent opening for introducing the concrete mix into the interior of the chamber. A reciprocably powered ram is carried by another frame portion and is located within the extrusion chamber so as to close the leading end thereof and operable to compact and extrude the concrete through the effluent end in a configuration dened by the interior shape of the chamber. Optionally, the ram is configurated to provide offset joints which are periodically extruded in a continuous length of concrete so that upon curing separation into Sections can be easily realized. A mandrel is centrally disposed within the chamber to impart a hollow core to the extruded concrete and vis controlled by the operator to, when desired, accommodate limited axial reciprocation of the mandrel generally in synchronism with at least part `of the stroke of the ram to thereby alter at least the initial frictional resistance to concrete displacement within the chamber. The two portions of the frame are telescopically interrelated to accommodate (a) displacement of the rear frame portion relative to the front frame portion coincident in time with a selected part of the stroke of the ram and (b) displacement of the front frame portion relative to the rear frame portion coincident in time with another selected partv of the stroke of the ram, to provide a variety of combinations of movement between the respective parts of the device to walk the apparatus during extrusion, insure proper consolidation of the concrete, and insure that little or no relative movement is occasioned between the concrete and the surface receiving the unset extruded concrete adjacent the eluent opening of the extrusion chamber.

This invention relates to an extrusion system and more particularly to. an apparatus for and method of extruding concrete and the like in a desired configuration so that the concrete will thereafter substantially retain its shape, set and cure without use of forms.

Although in no way negating the patentable nature of the present invention, the most pertinent prior art known to me at this time comprises U.S. Pats. 639,858; 772,319; and 3,292,227.

In summary, the present invention provides, in an extrusion apparatus and method, (a) capability to control the frictional resistance to concrete displacement prior to extrusion at predetermined times during the extrusion cycle, (b) capability to walk the vehicular apparatus by displacing the front portion of the frame relative to the rear frame portion and vice versa at selected times during the extrusion cycle so that concrete is extruded upon a desired surface without appreciable relative movement between the concrete as it is extruded and the mentioned surface and (c) capability of selectively forming partible joints in the extruded concrete product.

It is, therefore, a primary object of this invention to provide an improved apparatus and method for extrud- 1ng concrete and the like in a desired structural shape.

It is another important object of the present invention to provide an extrusion apparatus having a variable length frame, front and rear portions of which are movably related to each other for minimizing the likelihood of damage to the extruded product and/ or cyclically walking the apparatus in harmony with the extrusion cycle.

4It is another significant object of the present invention to provide a self-propelling extrusion vehicle and method adapted to attain advancement of the vehicle during the extrusion stroke of the ram so that the material as it is extruded remains generally stationary relative to the surface upon which it is extruded.

Another and no less important object of the present invention is to provide an apparatus and method which optionally control a mandrel to (a) hold the mandrel in a fixed position relative to the extrusion barrel, (b) release the mandrel for limited reciprocal movement with the extrusion ram or (c) rotate the mandrel about its longitudinal axis.

Another pertinent object of the invention is to provide an apparatus and method which, when desired, accommodate during extrusion the establishment of spaced joints along a continuous length of extruded concrete and the like.

These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective illustration of the presently preferred embodiment of the invention;

FIG. 2 is a fragmentary longitudinal cross-section taken along lines 2 2 of FIG. 1 showing the ram in its fully retracted start position;

FIG. 3 is an enlarged fagmentary cross-sectional view similar to FIG. 2 depicting the mandrel control mechanism with the ram in the start position;

FIG. 4 is a transverse cross-section taken along lines 4-4 of FIG. 1 illustrating in part the support of the extrusion chamber by the rear portion of the frame;

FIG. 5 is a transverse cross-section taken along lines 5 5 of FIG. 1 depicting the ram and extrusion chamber in part;

FIG. 6 is a transverse cross-section taken along lines 6 6 of FIG. 1 principally illustrating mandrel control mechanism shown in solid lines as accommodating reciprocal movement of the mandrel and in phantom as preventing such mandrel movement;

FIG. 7 is a fragmentary longitudinally cross-section similar to FIG. 2 depicting the ram in its fully extended nish position with the mandrel iixed in its initial stationary position;

FIG. 8 is a fragmentary longitudinal cross-section similar to FIG. 7 depicting the ram in fully extended position with the mandrel displaced to the left to its extended position;

FIG. 9 is a transverse cross-section taken along lines 9-9 of FIG. 2 primarily illustrating the two positions in which the mandrel-control mechanism may be placed to hold the mandrel stationary or permit displacement of the mandrel;

FIGS. 10-14 diagramatically illustrate the presently preferred sequential method steps practiced to extrude concrete pipe;

FIG. 15 is a fragmentary perspective illustrating another presently preferred ram embodiment that is longitudinally split into two segments to selectively accommodate placing one segment in offset relation to the other;

FIGS. 16 and 17 are fragmentary longitudinal cross sectional views depicting the split ram of FIG. 15, with one segment offset relative to the other, in its most ex- 3 tended position and in its most retracted position, respectively;

FIG. 18 is an exploded perspective view illustrating the dividing plates used to form a lap joint in a continuously extruded concrete pipe; and

FIG. 19 is a perspective view illustrating the lap pipe joint in its assembled, mortar-secured position.

One presently preferred embodiment of the invention is illustrated in the tigures, FIG. 1 generally depicting in perspective an extrusion vehicle 20 comprising a variable length frame 22. The front frame portion 24 is preferably telescopically received by the rear frame portion 26. It should be appreciated that although any suitable variable length frame structure could be used, the telescopically disposed frame 22 is presently preferred.

The front frame portion 24 principally comprises parallel tubular side elements 28 and 30 which are joined at the forward end by a front cross member 32. The cross member 32 carries a front master brake cylinder 34 and a front brake applicator or lever 36. The elements 28 and 30 are respectively provided with connecting structures 38 and 40 to which the wheels 42 and 44 are respectively suitably rotatably journaled. The wheels 42 and 44 are each provided with brake structure (not shown) which is preferably uid operated and connected by hydraulic lines 46 to the front master cylinder 34. Thus, when the applicator 36 is displaced clockwise as shown in FIG. 1, the front wheel brakes will be simultaneously applied. The wheels 42 and 44 are shown as being further provided with radially projecting anges 48 and 50 adapted to engage suitable tracks 51 and 52 respectively. The tracks 51 and 52, though not essential, are desirable to cooperate with the anged wheels 48 and 50 to maintain the vehicle 20 on a straight, predetermined course. Naturally other types of wheels with or without tracks could be used.

The front cross member 32 is integrally connected to an undercarriage 54 which extends downwardly and then rearwardly of the front frame portion 24. The undercarriage 54 comprises a lateral member 56 located somewhat below and essentially parallel to the front cross member 32. Longitudinal portions 58 and 60 extend essentially parallel to the side elements 28 and 30 and are connected at the terminal end to rear lateral members 61 and 62 (FIG. 5). The longitudinal portions are maintained in essentially horizontal relation by braces 64 and 66 which are joined to and depend from member 32. The purpose for the undercarriage 54 will be hereinafter discussed.

The rear telescopic frame portion 26 principally cornprises parallel tubular side elements 70 and 72 axially aligned with the side elements 28 and 30 of the front frame portion 24 and adapted at the forward ends 74 and 76 respectively to internally telescopically receive the corresponding side elements 28 and 30. The respective frame portions 70, 72, 28, and 30 are sized to accommodate relative slideable telescopic movement therebetween.

The rear side elements 70 and 72 are connected at the terminal ends 78 and 80 by a rigid rear cross member 82. The side elements 70 and 72 are further provided with depending connecting structures 84 and 86 to which wheels 88 and 90 are respectively suitably rotatably journalled. One set of wheels 88 and 90 being relatively movable with respect to the other set of wheels 42 and 44. The wheels 42 and 44 are shown as being provided with flanges 92 and 94 which respectively engage the tracks 51 and 52. Other types of wheels with or without tracks could be used. The wheels 88 and 90 are provided with braking structure (not shown) that are operable independent of the brakes on the wheels 48 and 50. The braking structure is operated by fluid pressure selectively developed in a rear master cylinder 96 and transmitted through suitable hydraulic lines 98.

The rear master cylinder is supported on a central cross member 100 integrally attached to members 70 and 72 4 adjacent the forward ends 74 and 76. The central cross member is preferably parallel to the rear cross member 82 and the front cross member 32 and sized to continually maintain the side elements 70 and 72 and the front side elements 28 and 30 in essentially parallel, coaxial relation. The central cross member 100 also carries the rear brake applicator 102 which is manually operable to actuate the rear braking structure. Although the front brake applicator 36 and the rear brake applicator 102 are illustrated as manually operable levers, it is to be appreciated that any suitable manually or automatically operable braking means could be used to selectively engage the front or rear brakes.

An extrusion barrel or tube is situated essentially mid-way between and below the rear side elements 70 and 72 and is maintained in a laterally stationary position by a plurality of essentially identical adjustable turnbuckle braces 112. Each turnbuckle brace 112, best illustrated in FIG. 4, is principally comprised of a sleeve 114 that is internally threaded at each end to respectively receive proximal ends 116 and 118 of axially aligned externally threaded rods 120 and 122. The threaded upper end 117 of each rod 120 is attached to a radially projecting lug 124 integrally carried by the rear telescopic frame portion. The lug 124 is compressively held between two nuts 12S threadedly positioned on rod 120.

Each lower-threaded rod 122 is likewise connected at its distal end 119 to an L-shaped bracket 130, which is compressively held between two nuts 131A threadedly positioned on rod 122. Each L-shaped bracket is integral with and projects from the extrusion barrel 110. Each brace 112 is angularly related with the respective frame portions 70 and 72 and the extrusion tube 110 such that, following assembly, the extrusion tube 110 will be disposed central of the transverse distance between and suliciently below the frame portions 70 and 72 so as to be located at about ground or floor level. If desired, an extrusion tube can be supported for extruding concrete pipe in an excavated trench or the like.

From the foregoing description, it is apparent that rotation of the threaded sleeve will change the effective length of the brace 112 and thus it is possible to center the extrusion barrel by adjusting the vertical position of the extrusion tube 110 and also, to a more limited extent, the lateral position. Although the above-described structure for supporting the extrusion tube 110 is presently preferred, clearly, other suitable strutcure could be used.

Referring to FIGS. 1 and 6 the longitudinal position of the extrusion tube 110 is xed by longitudinal brace rods 131 each nut connected at one end to a projecting tab 133 integral with the extrusion tube 110 and at the other end to a mandrel support frame 160 which will be hereinafter more fully discussed.

While other configurations and materials could be resorted to, the extrusion barrel 110 as illustrated comprises a cylindrical hollow metal tube 129 cut away at the bottom and an essentially flat metal plate 135 covering the cutaway bottom and located adjacent the ground or oor surface. The plate 135 extends from the leading end 142 of the tube 129 to a point considerably forward of the egress opening 132 of the extrusion barrel. The metal plate 135 is integral, as by welding, with the under-edges of the tube 129. The terminal end of the extrusion tube, rearward of the metal plate 135, opens rearwardly and downwardly in the form of a longitudinal slot 137 (see FIGS. 1, 2, 7 and 8). Internally, the extrusion barrel forms an extrusion chamber 136.

The illustrated embodiment is, therefore, essentially circular in cross-section and the concrete pipe 202 extruded thereform is essentially circular, but also presents a at undersurface, as illustrated in dotted lines in FIG. l.

The extrusion barrel 110 is further provided with a lateral ingress opening 138 in the top of the extrusion tube near the leading end thereof. The ingress opening 138 receives wet concrete mix from an adjacent inwardly tapered hopper 140. The hopper 140 is adapted to receive concrete mix and funnel it into the ingress opening 138 to facilitate periodic filling of the extrusion chamber 136.

The leading end 142 of the extrusion tube 110 is closed by a reciprocable ram 144 which is exteriorly configurated to conform to the interior of the extrusion chamber 136.

The ram 144 is externally dimension to accommodate free to and fro movement within the extrusion barrel 110 without permitting concrete mix to become wedged between the ram and the Wall of the extrusion chamber 136.

The ram 144 is optionally provided with apertures 146 offset from though parallel to the axis of the ram which accommodate insertion reinforcement (not shown) into the concrete mix within the extrusion chamber 136 (see (FIG. 5). For convenience, the lowermost aperture 146 is not illustrated in the gures depicting the ram in longitudinal cross-section.

The leading end of the ram 144 is integrallyyy attached to each of the lateral members 61 and 62 of the undercarriage 54, as illustrated in FIGS. 2, 3 and 5. It can thus be appreciated that as the front telescopic frame portion 24 moves relative to the rear telescopic frame portion 26 the ram 144 will move relative to the extrusion chamber 136 and vice versa.

The ram is preferably centrally hollow to receive a mandrel 148 which is shown as comprising an elongated tube, preferably formed of metal, extending through the entire longitudinal length of the ram and projecting from each end thereof. The exterior surface of the mandrel 148 is in close tolerance frictional contact with the interior sur face of the ram 144 so that the ram 144 may be independently moveable along the mandrel 14-8. In the illus- `trated embodiment of the invention, the contact between ram 144 and mandrel 148 has the desirable effect of preventing concrete mix from flowing between the ram and mandrel.

As best illustrated in FIGS. 2-9, the mandrel 148 is shown as being disposed essentially coaxial with the extrusion chamber 136 and the ram 144 and is attached at its leading end 150 to a mandrel support sleeve 152 (see FIGS. 3 and 9.). The mandrel support sleeve 152 is contained by a collar 163 forming part of the mandrel support frame 160.

The support frame 160 is carried by the central cross member 100 and vertically depends therefrom. The position of the frame 160 is maintained immoveable by braces 159 and 161 respectively diagonally disposed between frame 160 and the connecting structure 84 and 86 adjacent the wheels 88 and 90.

The leading end 150 of the mandrel 148 is provided with an integrally attached, diametrically disposed guide and latch pin 154 having a length somewhat greater than the diametral dimension of the mandrel 148 (see FIGS. 3 and 9). Thus, each remote end of the guide pin 154 extends somewhat beyond the periphery of the mandrel 148. Opposed axially disposed guide slots 156 and 158 (FIGS. 3, 8 and 9) in the annular sleeve 152 open at the leading end 162 of the sleeve 152 and terminate just forward of the trailing end 164 (FIG. 3) of the sleeve.

The axially disposed slots accommodate limited axial movement of the mandrel and attached guide pin 154 when the pin is aligned in the slots and, conversely, prevent axial movement of the mandrel 148 when the guide pin 154 is rotated out of alignment with the slots 156 and 158, as shown in dotted lines in FIG. 9. The sleeve 152 and the guide slots 156 and 158 could be sized and shaped to accommodate any one of a variety of axial displacement distances. If desired, the mandrel could be adapted to be rotated continuously to help in consolidating the concrete and to reduce the extrusion force required for satisfactory operation.

A mandrel control lever 166 is fixed to the mandrel 148 between the leading end 150 of the mandrel and the leading end of the ram 144. The control lever 166 can be manually manipulated to force the mandrel axially forward a short distance such that the guide pin 154 is extended out of the sleeve 152 and free of the guide slots 156 and 158. The control lever 166 may then be rotated, as illustrated in dotted lines in FIGS. 6 and 9, to correspondingly rotate the guide pin 154 out of alignment from the guide slots 154 and 156 and thereby prevent rearward axial displacement of the mandrel 148 during the stroke of the ram. Conversely, the mandrel control lever 166 can be later rotated bringing the guide pin 154 into alignment with the opposed slots 156 and 158 to facilitate limited rearward displacement of the mandrel 148 with the ram.

The mandrel 148 is further provided with two radially disposed ram abutment stops 168, illustrated in the presently preferred embodiment as diametrically opposed one to the other. When the mandrel is located in the maximum rearward extended position at the end of the extrusion stroke of the ram, the ram 144 will engage the abutments 168 during the retraction stroke of the ram to cause the mandrel 148 to be simultaneously forwardly retracted.

.The mandrel support frame is further adapted to plm-support the bifurcated trailing end 170 of a conventional two-way hydraulic cylinder 172, as shown in FIGS. 2 and 3. The cylinder piston rod 174 is pin-con nected to the transverse member 56 of the undercarriage 54. The hydraulic cylinder 172 is connected by pressure lines 176 and 178 to a hydraulic valve 180` also carried by the central cross member 100. Manipulation of the handle 182 on the valve 180 will selectively displace a valve spool causing the piston rod 174 to advance or retract depending on the direction in which handle 182 is displaced this in turn causing relative extension or retraction of the front and rear telescopic frame portions 24 and 26. The valve and the cylinder 172 are supplied with hydraulic lluid under-pressure by a commercially available source (not shown) through input lines 184 and 186. FIGS. 10-14 illustrate sequential steps to be followed 1n the formation of concrete pipe. First a supply of wet settable concrete mix 200 or similar settable plastic mix 1s placed in the hopper 140. The concrete mix falls by force of gravity through the ingress opening 138 into the extrusion chamber 136 when the ram 144 is in its fully retracted position, as illustrated in FIG. 10. It should be observed, that with the rear brakes applied retraction of the piston rod 174 displaces the carriage 54 and the frame portion 24 rearward and advances the ram 144 toward the rear of extrusion barrel 110. Extension of the piston rod in like manner retracts the ram 144 forward. Thus, when the ram 144 is in its most retracted position, the telescopic frame portions 24 and 26 will be disposed at theirI greatest cumulative length.

When a quantity of concrete mix 200 has filled a portlon of the extrusion chamber 136, the undercarriage 54 is caused by retraction of the piston rod 174 of the hydraulic cylinder 172 to displace the ram 144 rearward in the extrusion chamber 136, thus compressing and compacting the concrete mix as it is forced to move against frictional resistance presented by the surfaces of the extrusion chamber 136 and the mandrel 148. As the ram 144 is advanced toward the rear in the chamber 136, the front wheels 42 and 44 are displaced in unison toward the braked or otherwise restrained rear wheels 88 and 90. This decreases the effective length of the vehicle 20, as illustrated in FIG. l1. As the ram 144 is advanced to forcibly displace the concrete mix 200` it simultaneously closes the ingress opening 138 adjacent the hopper 140 but does not cause the front edge of the ram 144 to be exposed at opening 138 which could otherwise lead to deposition of concrete on the Wrong side of the ram.

When the ram is fully extended such that the rear lateral member 62 of the undercarriage 54 abuts or nearly abuts the extrusion tube 129, the hydraulic cylinder 172 is actuated to reverse the direction of motion and cause the front Wheel 42 to be displaced away from the rear wheel 88, thereby increasing the effective length of the vehicle 20. This displacement causes the ram 144 to be forwardly retracted away from the ingress opening 138 to accommodate ingress of additional concrete mix into the extrusion chamber 136, as shown in FIG. 12.

The described stroke of the ram, illustrated in FIGS. 10-12 is serially repeated until the concrete pipe 202 thus formed begins to emerge from the terminal end 132 ofthe extrusion tube 129 (see FIG. 12).

The ram 144 is then again retracted. At this point in time the rear brakes are released. When the ram 144 is thereafter advanced toward the rear in the extrusion chamber 136, the rear wheels 88 and 90 will advance toward the front of the vehicle because of dynamic engagement of the concrete being extruded and the ground and the front wheels 42 and 44 will move toward the rear of the vehicle, as illustrated in FIG. 13. This will cause the rear frame portion 26 and the extrusion barrel 110 to advance forward, and the front frame portion 24 and the ram 144 to be displaced toward the rear while the concrete pipe 202 being extruded remains in essentially a fixed position. Thus, the concrete pipe 202 during extrusion will rest upon and remain essentially stationary relative to the ground or floor surface as the vehicle is displaced relative to the ground. Consequently at the same time concrete is being extruded the concrete is also being consolidated, the amount of consolidation being controlled by the lack of application or the magnitude of application of the front and/or rear brakes.

If desired, during extrusion, the front brakes may be applied to hold the front wheels and the front frame portion in the position of FIG. 12 as the rear wheels and rear frame portion are displaced forward.

Thereafter the ram 144, along with the front frame portion 24, is displaced to its forwardmost retracted position, as illustrated in FIG. 14. Then, the described extension and retraction strokes of the ram are repeated until the desired length of pipe has been formed. Under controlled viscosity conditions, the pipe will essentially retain its extruded shape and will later set and cure in that configuration.

During the extrusion process, the frictional resistance developed between the wet concrete mix and the surfaces of the mandrel 148 and the extrusion chamber 136 may become sufficiently high as to unduly restrain effective displacement of the ram 144. The present invention provides a unique and effective structure and method of overcoming this high initial resistance. More specifically, it is well known in the art that the force required to overcome sliding frictional resistance to a moving object is substantially smaller than the force required to overcome static frictional resistance when the object is stationary. Static friction in this specification means that frictional resistance presented by stationary surfaces within the extrusion barrel 110 to any subsequent movement of an initially at rest portion of concrete mix. Sliding friction in this specification means frictional resistance presented by stationary surfaces to concrete mix already in motion within the extrusion chamber 136.

TABLE I.-(REFE RENO E Rear wheels The structure for converting controlling frictional resistance to displacement of concrete within the extrusion chamber 136 (best shown in FIGS. `2, 3 and 6-9) cornprises the mandrel 148, the lever 166, the pin 154 and structure related to pin 154. The mandrel 148 is controlled by the handle 166 and the mandrel guide pin 154 and guide slot 156 as will be described. In the event static frictional resistance to concrete displacement is not sufficiently high as to seriously inhibit the movement of the ram 144, the mandrel control lever 166 is located in the position shown in phantom lines in FIGS. 6 and 9. The lever 166 thus provides for location of the guide pin 154 out of alignment with the guide` slots 156 and 158 and thus prohibits axial movement of the mandrel 148 during the rearward extension stroke of the ram. It can be appreciated therefore, that as the ram 144 is actuated for displacement relative to the extrusion barrel 110, initial static frictional resistance will be presented by both the surface of the extrusion chamber 136 and the exterior surface of the mandrel 148. Once the concrete in front ot the ram begins to be displaced by extension of the ram, sliding frictional resistance will then be encountered at the two mentioned surfaces.

`On the other hand, when the static frictional resistance at both surfaces is sufficiently high to seriously inhibit or prevent displacement of the ram 144, the mandrel control lever 166 may be manually moved to the position illustrated in solid lines in FIGS. 6 and 9. The lever 166, thus located, aligns the ends of the guide pin 154 with the guide slots 156 and 158 and accommodates axial displacement of the mandrel 148, with concrete displaced by the ram, through the entire length of the guide slots 156 and 158 (see FIG. 8). Thus, with the mandrel control lever 166 in the full-line position shown in FIGS. 6 and 9, as the ram 144 advances against the concrete mix, the mandrel 148 will concurrently advance a short distance so that, initially, the only static friction resisting the movement of the concrete mix is presented by the chamber 136. As soon as this static frictional resistance has been overcome, only sliding frictional resistance at the chamber wall 136 will be encountered. Once the guide pin 154 reaches the end of the slots 156 and 158, the movement of the mandrel 148 with the concrete will be immediately terminated, and instantaneous static frictional resistance which will immediately become sliding frictonal resistance will be presented by the exterior mandrel surface. It is therefore apparent that the initial frictional resistance presented by the extrusion chamber 136 and the mandrel 148 with the mandrel in its displaceable condition is considerably less. On retraction frictional resistance only at the exterior surface of the mandrel will be encountered as the mandrel is returned to its original position relative to the stationary concrete.

With the foregoing in mind, attention is called to the variety of possible combinations of relative movements between (a) the rear wheels and extrusion barrel, (b) the mandrel and (c) the `front wheels and ram which may be used to successfully extrude concrete pipe. In this regard attention is directed to Tables I and II below. Table I specifies various possible conditions of the extruder and components thereof at various times during the extrusion process. Table II summarizes the combination of movements relative to the ground inherent in the presently preferred embodiment of the invention.

STATION: GROUND) and extrusion Front wheels Hydraulic Extrusion barrel Mandrel and ram cylinder at exit; end Comments Condition:

1 B-S S NB-F O S Opening recharge chamber.

2 NB- F NB-S C S Concrete extruding.

3(a) B-S l, S NB-`R (l Slight R ..{Concrete extruding: Brake release based on obseriith) Tl1onNI-1", F Nil Hoi-S (l S. vallon of operator or automatic sensing device.

See note at end of table.

TABLE I-JContinued Rear wheels and extrusion Front wheels Hydraulic Extrusion barrel Mandrel and ram cylinder at exit end Comments 4 NB-F F NB-R C S Concrete being consolidated in extrusion barrel at the same time the concrete is extruding at extrusion barrel exit.

B-S C S Concrete extruding.

B-S C F Concrete extrusion being separated at extrusion barrel.

NB-R C R Concrete extrusion sliding on receiving surface at v extrusion barrel exit.

N B-F O S Mandrel being pulled through concrete in extrusion barrel friction along mandrel surface only.

NB-R C R Mandrel floating in concrete of extrusion barrel. Concrete sliding on receiving surface of extrusion barrel exit.

S Mandrel floatingH while concrete is consolidating in extrusion barrel.

S Mandrel floating as concrete is being extruded friction on extrusion barrel only.

R Concrete extrusion sliding on receiving surface at extrusion barrel exit.

R Do.

S Concrete is being consolidated in extrusion chamber.

S- Mandrel "oating while concrete is extruding.

R. Mandrel being pulled forward while extrusion is being pushed rearward.

17 NB-R R R Concrete extrusion sliding on receiving surface at extrusion barrel exit.

NOTE .-D efinition of Symbols:

C =Hydraulic Cylinder Closing. O =Hydraulic Cylinder Opening. NB =Not Braked. SB Slight Brake. B Braked. S Stationary. l F Forward Mt1on. R Rearward Motion.

TABLE II Front wheels Rear Wheels and Extrusion Barrel Mandrel and ram Forward. Forward Stationary.

Reawvard.

Forward. Stationary Stationary.

Rearward.

FORWARD Forward Rearward.. Stationary.

Rearward Forward. Forward Stationary.

Rearward.

Forward. Stationary Stationary.

Rearward.

STATIONARY Forward. Rcarward. Stationary.

Rearward.

Forward. Forward Stationary.

R earward Forward. REARWARD Stationary Stationary.

Rearward.

Forward Rearward- Stationary.

R earward It is presently preferred that the upper portion 208` be disposed a greater distance rearward in the extrusion barrel than the lower portion 210, as shown in FIGS. 16 and 17. This may be accomplished by releasing the collar 212 and displacing the portions 208 and 210 relative to each other. This position is then fixed by tightening the collar 212 until relative movement under load is prohibited.

As concrete mix is extruded with the ram 206 in the mentioned offset configuration, the resulting pipe 202 will have a stepped end adjacent the ram at the end of each extension stroke. When the ram 206 is thereafter in its fully retracted position, a lower transverse plate 222 in the form of a semi-annular disc and an upper transverse plate 224 in the same though inverted form are manual- 1y placed around the mandrel 148 in abutment with the two vertical surfaces on the stepped end of the pipe. See FIGS. 17 and 18.- Longitudinal plates 226 and 228` of desired length are placed upon the horizontal surfaces of the stepped end of the pipe. Additional concrete mix is then introduced into the chamber 136 through the ingress opening 138. Continued extrusion of concrete pipe 202i produces two pipe segments 214 and 230 which, after setting, are separable o-ne from the other, as illustrated in FIG. 18. Of course, the described technique for forming a stepped joint between pipe sections can be repeated as often as desired to continuously produce as many pipe sections as desired.

The second pipe section 230 is, therefore, provided with vertical surfaces 232 and 234, which compliment vertical surfaces 216 and 220, respectively, of pipe section 214, and with horizontal surfaces 236, which are adapted to mate with surfaces 218 of pipe section 214 when joined by mortar 238 or the like, as shown in FIG. 19. It should be appreciated that the pipe segments 214 and 230 and the stepped joint therebetween may be any desirable length.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

What is clamied and desired to be secured by Letters Patent is:

1. In a concrete extrusion apparatus: a variable length frame having a front frame portion reciprocable relative to a rear frame portion, an extrusion chamber carried by one frame portion, the chamber having an opening at the trailing end thereof, a reciprocable plunger for compacting concrete within and extruding concrete from the charnber closing the leading end of the chamber and being carried by the other frame portion, feeding structure to communicate concrete mix to the interior of the extrusion chamber, power means interposed between the part of the apparatus comprising the one frame portion and the chamber and the part of the apparatus comprising the other frame portion and the plunger such that actuation of the power means will cause (a) relative reciprocation between the plunger and the chamber, the reciprocation comprising extension and retraction strokes to compact and extrude the concrete, and (b) forward displacement of the rear frame portion relative to the front frame portion during extrusion at a rate substantially equal to the rate of extrusion.

2. In an apparatus as defined in claim 1 wherein said variable length frame is telescopic and wherein the frame is mounted upon front and rear wheels at the front and rear frame portions, the wheels being provided with independent braking structure such that when (a) the rear frame portion is braked the front frame portion can be released to travel responsive to the stroke of the plunger and (b) the front frame portion is braked the rear frame portion can be released to travel responsive to the stroke of the plunger whereby the apparatus may be cyclcally propelled and substantially no relative movement will be caused between the ground and the concrete as the concrete is extruded from the chamber upon the ground.

3. In an apparatus as defined in claim 1 further comprising mandrel means situated within the chamber to provide the extruded concrete with at least one passageway, the mandrel means being associated with control structure to selectively hold the mandrel means stationary relative to the chamber during the extension and retracting strokes or accommodate reciprocation of the mandrel means with the plunger relative to the chamber during the' extension and retraction strokes so that the frictional resistance to concrete displacement within the chamber encountered at the interior of the chamber and at the ext'erior of the mandrel means will be incurred at separate tlmes.

4. In an apparatus as defined in claim 1 wherein said feeding structure comprises an upstanding supply hopper positioned adjacent a side ingress port in the extrusion chamber so that concrete mix placed in the hopper s made 4continuously available to the interior of the chamber by force of gravity and wherein the extension stroke of the plunger does not expose the back of the plunger at the ingress port.

5. In an apparatus as defined in claim 1 wherein the plunger is provided with spaced apertures adapted to pass reinforcement into the concrete mix located within the chamber.

6. In an apparatus as defined in claim 1 wherein the power means comprises at least one hydraulic cylinder fastened at its two ends respectively to the front frame portion and the rear frame portion whereby relative movement between the plunger and the chamber is accompanied by corresponding relative movement between the front frame portion and the rear frame portion all in response to extension and retraction of the hydraulic cylinder.

7. In an extrusion vehicle comprising in combination first and second frame components telescopically connected for selective relative movement, the frame components being supported upon rotatable sets of wheels and each frame component having an independent braking structure, an extrusion chamber carried by and comprising part of one frame component and provided at its upper surface with a mix ingress opening and an associated receptacle for receiving and feeding to the interior of the extrusion chamber a settable mix in a plastic state, said extrusionchamber having a mix egress opening at the trailing end thereof, a mandrel centrally disposed in the extrusion chamber, a ram carried by and comprising part of the other frame component and located within the extrusion chamber closing the leading end thereof adapted to compact and extrude the mix before curing and generally conforming to the interior shape of the chamber, the ram centrally receiving the mandrel and being reciprocally actuated by motor means interposed between the frame components, the mandrel being equipped with a control to selectively accommodate movement of the mandrel fore and aft along with at least part of the cycle of the ram or the holding stationary of the mandrel as the ram is reciprocated, whereby controlled actuation of the motor and braking structure will cause at the election of the operator (a) independent displacement of the second frame component relative to the first frame component coincident in time with the stroke of the ram and (b) independent displacement of the first frame component relative to the second frame component coincident in time with the stroke of the ram.

8. In a concrete extrusion apparatus: elongated extrusion barrel means with a concrete influent for receiving wet cohesive concrete mix, said barrel means being open at its etiiuent end, reciproeable ram means for cyclcally consolidating the concrete mix within the barrel means and mandrel means disposed within the barrel means in spaced relation thereto and associated with selectively positionable mandrel-control means which (a) when set in one position accommodates reciprocal displacement of the mandrel means generally in the same direction of and simultaneous with at least part of the reciprocal stroke of the ram means and (b) when set in another position accommodates holding of the mandrel means in essentially a stationary position during the reciprocal stroke of the ram means.

9. In an extrusion vehicle. a first wheel-mounted support means carrying mold means for receiving settable mix in a plastic condition, the mold means being provided with a trailing open end, a second wheel-mounted support means carrying piston means adapted to reciprocate within the mold means to compress and extrude the mix prior to setting, the second support means being joined to the first support means to selectively accommodate relative movement between the two support means, situated between the first and second support means to control the reciprocation of the piston and to control the relative movement between the first and second support means, brake means associated with the support means to, upon command, hold the first support means in position while the second support means is relatively moved by the motor means or vice versa.

10. In an apparatus as defined in claim 1 wherein the plunger presents a discontinuous face adjacent the concrete within the extrusion chamber to accommodate formation of at least one joint along the length of the concrete being extruded.

11. In an apparatus as defined in claim 10 wherein the plunger is axially split into opposed sections which are clamped in axially offset relation presenting said plunger face discontinuity comprising a stepped configuration to form a lap joint in the extruded concrete.

12. In an extrusion apparatus: (a) an extrusion barrel associated with one set of wheels for joint motion, (b) means for selectively braking said one set of wheels, (c)

a selectivelydisplaceable mandrel situated within the extrusion barred; (d) a ram associated with a second set of wheels for joint motion, said sets of wheels being relatively movable with respect to each other, and (e) means for selectively braking said second set of wheels whereby components (a), (c) and (d) may be respectively con trolled to remain stat'onary, move forward, and move rearward to provide twenty-seven combinations of motion.

13. In a concrete ext \usion apparatus: elongated extrusion barrel means With aconcrete influent for receiving wet cohesive concrete nix, said barrel means being open at its eluent end, reciprocable ram means for cyclically consolidating the concrete mix within the barrel means and mandrel means disposed within the barrel means in a spaced relation thereto, said mandrel means and ram means being in contact so to substantially prevent concrete mix from owing between the ram means and mandrel means, and associated with selectively positionable mandrel control means which (a) when set in one position accommodates movement of the mandrel 14 means with respect to the ram means and (b) when set in another position accommodates holding of the mandrel means in essentially a stationary position during the reciprocal stroke of the ram means.

References Cited r I. SPENCER OVERHOLSER, Primary Examiner o B. D. TOBOR, Assistant Examiner U.S. Cl. X.R.

Patent No.

Inventor(s) Glen H It is Certified that error appears and that said Letters Patent are hereby Column 5 line 2l, the word "ntegrallyyy" Calder' Dated September 2%-, 1970 Column l2 ,l line 56 -fmeansJ motor' means situated-. ,I

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'IDEC' 151m mlm E'. omissions@ in the above-identified patent corrected es shown below:

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