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Publication numberUS3399441 A
Publication typeGrant
Publication date3 Sep 1968
Filing date13 Dec 1965
Priority date13 Dec 1965
Publication numberUS 3399441 A, US 3399441A, US-A-3399441, US3399441 A, US3399441A
InventorsImamura Yukio
Original AssigneeImamura Yukio
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High speed recoilless chisel device
US 3399441 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)



United States Patent "ice P 1 3,399,441 HIGH-SPEED RECOILLESS CHISEL DEVICE .Yukio Imamura, 1156-1, Renjaku, Fujinomiya, Shizuoka Prefecture, Japan v Filed Dec. 13, 1965, Ser. No. 513,358

.. l. 1 Claim. (Cl. 29-81) ABSTRACT F THE DISCLOSURE A primary object of the present invention is to provide a highspeed recoilless chisel device in which an actuating member is caused to move reciprocally in the vertical direction withinthe casingv of the device so as to cause chopping tools movably disposed in the actuating member to initiate to move reciprocally in the vertical direction within an operation space defined b the actuating member and after the initial movement the chopping tools then continue to move reciprocally only by their force of inertia.

1 *Another'obje'ct of the present invention is to provide an improved high speed recoilless chisel device of the above type which can be utilized for various industrial purposes such as scrapping-off of slags on weldments, chopping-off of beads on weldments, rough finish, breaking and boring of concrete constructions, removing of casting fins,'impact transmission and the like.

"According to the present invention, there is provided an improved high-speed recoilless chisel device which can "effectively perform the above purposes and in which 'an actuating member is actuated so as to move reciprocally in the vertical direction within the casing of the device and-the reciprocal movement of the actuating member'is'then transmitted to chopping tools disposed within anoperating space defined by the actuating member so as to develop aforce of inertia in the tools which will "then cause the chopping tools to move reciprocally toward and away from a work on which a desired operation is'to be'performed. The above and other objects, features and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed explanation" of two preferred embodiments thereof in conjunction with the accompanying drawings.

- In the drawings:

FIG. 1 is a fragmentary vertical sectional view of a first, embodiment of chisel device constructed in accordance with the present invention;

,-.FIG-. 2 is a cross sectional view substantially taken along the line II- II of FIG. 1;

FIG. 3 is a cross sectional view substantially taken along the line IIIIII of FIG. 1; and

FIG. 4 is a fragmentary view showing one of chopping tools employed in said chisel device illustrated in FIG. 1.

Now referring to the figures of the drawings, especially to FIG. 1 in which 'a first preferred form of chisel device according to the present invention is shown. As seen from this figure, the first embodiment of chisel device generally comprises a hollow main body or casing 1 which houses various elements constituting the device and has a cover 2 which is removably secured to the top of the casing in the conventional manner. An electric motor 3 is mounted within the cover 2 in the conventional manner and one end of the motor has an 3,399,441 Patented Sept. 3, 1968 electric cord attached thereto (not shown) which is adapted to be connected to a suitable electric source (not shown). The other end of the motor 3 has an output shaft 4 extending downwardly and having a reduced diameter portion 4' provided with splines-The reduced diameter portion 4' of the motor output shaft 4 extends into the casing 1 and is journalled in bearings 5 disposed in an opening 6 formed in the top wall 1 of the casing 1. The larger diameter portion of the output shaft 4 has a cooling fan 7 disposed around theperiphery thereof. A gear frame or box 8 is secured to the casing 1 by any suitable means such as bolts and the, gear box houses a gear 9 which engages with the reduced diameter splined lower portion 4' of the motor shaft 4. The gear 9 is rigidly mounted .on a rotational shaft 10 whose reduced diameter one end is loosely received in a sleeve member 11 disposed within a recess formed. on the. underside of the top wall 1' of the casing 1 adjacent to the opening 6 which receives the bearings 5 which journal the splined lowerportion 4' of the motor shaft 4 and the other end of the shaft 10 is journalled in bearings 12 disposed within an opening 13 formed on the bottom wall 8' of the gear box 8. The intermediate portion of the shaft 10 between the opposite ends thereof is threaded for receiving 'a bearing retainer 14 which has an inner thread and serves to hold the bearings 12 in position. A circular mounting member 15 is rigidly secured to the lower journalled end of the rotational shaft 10 by any suitable means such as pins (not shown) for rotational movement therewith. The top surface of the mounting member 15 lies in the horizon whilst the undersurface thereof is slanted with respect to the horizon as indicated with a. The mounting member 15 has a downwardly extending hollow boss or shaft 16 the axis of which is .eccentric with respect to or deviated from the axis of the mounting member 15 for the reason to be described hereinafter and has an inner thread. A swinging member 17 which comprises a hollow cylin drical body 17' and .a laterally projecting extension or arm 17" having a spherical tip end 17" is swingingly mounted on the eccentric shaft 16 of the mounting member 15 for a cranking movement with bearings 18 interposed between the shaft 16 and the hollow body 17'. The bearings 18 are held in position by screwing a head bolt 19 into the threaded bore of the shaft 16 with a washer 20 interposed between the lower end of the shaft 16 and the head of the bolt 19. The swinging member 17 is adapted to swing about the eccentric shaft 16 in a cranking movement while sliding along the slanted undersurface a of the mounting member 15. A stationary hollow cylindrical member 21 having an opening 21 on one side is provided below the gear box 8 in a position for receiving the substantial portion of the laterally projecting arm 17" of the swinging member 17 and the size of the opening 21 is sufliciently large to allow the cranking movement of the swinging member 17. The lower portion of the stationary hollow cylindrical member 21 is externally threaded for the purpose to be explained hereinafter. A vertically slidable hollow cylindrical actuating member 22 is received within the outer stationary cylindrical member 21 and has a plurality of air bores 22' in its periphery. The actuating member 22 has a circular intermediate partition 22" which extends across the diameter of the member 22 and defines an operation space or chamber b in cooperation with the top wall 22" of the actuating member and into which the spherical end 17" 0f the 'arm 17" of the swinging member 17 extends. The size of the operation space b is so selected that the spherical arm end 17 may freely move therein, but the end 17" may also maintain its slide contact relation with the inner surface of the top wall 22" and the inner surface of the intermediate 3 partition 22" and the space b is outwardly flared at one end as defined by the beveled one ends of both the wall and partition. The inner surface of the lower portion of the act-uating member 22 is provided with an annular recess and a solid cylindrical guide member 23 having a plurality of through bores 23 is received within the recess c whereby a space or chamber d is defined between the intermediate partition 22" of the member 22 and the guide member 23. The size of the bores 23' is slightly larger than the diameter of one of chopping tools of which explanation will be made hereinafter so that the tools may freely move reciprocally in the vertical direction while being restrained from inclining during the operation. The guide member 23 may be held in position by any suitable means such as an annular ring 24 as illustrated. A plurality of chopping tools which are illustrated in the form of nail 25 extend through the respective bores 23' of the guide member 23 and these nails 25 are disposed with their heads abutting against the top surface of the guide member 23 as shown in FIG. 1 when they are in their inoperative position. A reversed frusto-conical shaped hollow end member 26 having a thread on the inner surface of the upper larger diameter portion thereof is screwed onto the externally threaded lower portion of the stationary cylindrical member 21. Thus, it will be understood that the frusto-conical end member 26 serves as a constriction and guide means for the group of chopping tools 25 in addition to its function as the tip end portion of the casing 1.

In the operation of the above mentioned chisel device by the present invention as described above, the motor 3 is first actuated in the conventional manner so as to rotate its output shaft 4. The rotational movement of the shaft 4 is transmitted through the gear 9 which is in engagement with the shaft 4 to the mounting member which in turn transmits its rotational movement to the eccentric shaft 16 which is integral therewith. The thus actuated eccentric shaft 16 causes the swinging member 17 to swing in a cranking movement while sliding along the slanted undersurface a of the mounting member 15 and accordingly, the spherical arm end 17" is caused to move upwardly and downwardly in sliding contact with the inner surfaces of the top wall 22" and intermediate partition 22" of the actuating member 22 so as to effect the reciprocally vertical movement of the actuating member 22. Such reciprocal movement of the actuating member 22 in turn effects the vertical reciprocal movement of the group of chopping tools 25 at a high speed and the thus actuated chopping tools are caused to strike against a work on which a desired operation is to be performed. In this way, after the actuating member 22 has once been forced to descend at a high speed with a high impact applied thereon by the rotating swinging member 17 so as to transmit the thus applied high impact onto the chopping tools 25 by the latters heads and thereby the tools have in turn descended at the same high speed toward the work to transmit the high impact onto the work, the actuating member 22 is rapidly forced to ascend because the inner surface of the intermediate partition 22" of the actuating member is struck by the heads of the chopping tools 25 which are rapidly ascending by the repelling force which has been generated due to the striking of the chopping tools 25 against the work with the high impact. When the chopping tools 25 are operated in the manner as mentioned just above, their cyclic striking etficiency is augmented because their ascending movement after their descent for striking against the work is C I. 3 abruptly halted by the intermediate partition 22" of the actuating member 22 the ascending movement of which is also abruptly halted byithe rotating swinging member 17. The above cycle of operation of the actuating member 22 and chopping tools 25 is allowed to continue so long as the electric motor 3 is rotating and accordingly, the swinging member 17 is rotated thereby. However, in this case, the energy which has been generated due to the operation of the chopping tools .25 in the manner mentioned above can be effectively prevented from being transmitted to the hands-of the operator because the swinging member 17 which is rotating at high speed prevents such transmittance of energy and therefore, the degree of fatigue on the part of an operator may be substantially less as compared with that experienced with the conventional chisel devices. Furthermore, the novel'chisel device is far more safer than the conventional chisel devices because no kickback. takes place during the operation of the novel chisel device which have frequently taken place on the conventional chisel devices.

What I claim is: a t

1. A high speed recoilless chisel. device comprising, in combination, a hollow casing, an electric motor mounted in said casing and having a geared drive shaft, a transmission gear drivingly engaging said shaftand having a second shaft on which said transmission gear is rigidly mounted for rotational movement therewith, a mounting member rigidly secured to one end of said second shaft of the transmission gear and having an undersurface obliquely disposed to the axis of said second shaft and an eccentric stud extending downwardly from said oblique surface, a swinging member mounted on said stud of the mounting member for cranking movement around said eccentric stud and having a laterally extending arm having a spherical tip end, a stationary hollow cylindrical member afiixed to said casing having an opening in its periphery for slidably receiving said arm of the swinging member, an axially movable hollow cylindrical actuating member disposed within said stationary cylindrical member for sliding movement therein having an operating chamber for receiving said spherical tip end of the swinging member 'arm which reciprocates said actuating member as said swinging member swings in a cranking movement, a guide member disposed within said actuating memberand having a plurality of bores extending therethrough, a tool slidably extending through each of said bores of the guide member and adapted to move reciprocally within said actuating member under inertia forces and a'hollow end extension member secured to the lower end of said casing through which said tools extend for guiding and c0nstricting said tools.

References Cited UNITED STATES PATENTS 2,455,626 12/ l948 Traut 74-45 2,491,624 12/1949 Shaff 74-60 2,824,455 2/ 1958 Ristow et al 74-60 3,150,888 9/1964 Parker 29-81 3,343,246 9/1967 Kelley et al. 2981 OTHER REFERENCES German printed application, Renz, 1,027,039, March 1958.

WALTER A. SCHEEL, Primary Examiner.

J. M. NEARY, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2455626 *24 Jun 19447 Dec 1948Blackhawk Mfg CoMechanical movement for converting rotary motion into reciprocating movement
US2491624 *29 Mar 194520 Dec 1949Keller Tool CoTool operating mechanism
US2824455 *27 Jun 195225 Feb 1958Milwaukee Electric Tool CorpPortable reciprocating saw
US3150888 *8 May 196229 Sep 1964Ingersoll Rand CoCoupling means
US3343246 *29 Oct 196526 Sep 1967Walter I AndersonScaling tool
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4446931 *14 Sep 19818 May 1984Robert Bosch GmbhPower driven hammer drill
US4456076 *30 Jun 198126 Jun 1984Robert Bosch GmbhPower-driven hand tool
US4487272 *27 Sep 198211 Dec 1984Robert Bosch GmbhImpacting drill
US4537264 *19 Mar 198427 Aug 1985Robert Bosch GmbhPower-driven hand tool
US4605073 *27 Jun 198412 Aug 1986Nilsson Goran AlfredDevice in needle hammers
US4821357 *23 Feb 198818 Apr 1989Edgar MilletteScraper adaptor for rotary buffer
U.S. Classification29/81.14, 74/60, 173/51
International ClassificationB25D11/06, B25D17/02, B25D17/06, B08B7/02, B25D15/02, B25D17/08
Cooperative ClassificationB08B7/022, B25D11/062, B25D17/06, B25D2250/291, B25D17/08
European ClassificationB25D11/06B, B08B7/02B, B25D17/08, B25D17/06