US 2266415 A
Description (OCR text may contain errors)
De.16, 1941. RWDINZL .2,266,415
PRESS Filed March 31, 1941 l l 1 g Umb' M/ZQ ATTORNEY Patented Dec. 16, 1941 vUNITED STATES PATENT oEFIcE l PRESS Y Richard W. Dinsl, Weatiield, N. J., aligner to The Watson-Stllhmn Co.. Roselle, N. J., a corporation of New Jersey Application March 31, 1941, Serial No. 386,010
3 Claims. (Cl. 121-48) The present invention relates more particularly to improvements in means for controlling movement of a press ram in a hydraulic press. An important object of the invention is to provide simple and satisfactory means for causing rapid advance of theram toward the work during a preliminary portion of the ram stroke and then. during a following portion of the stroke and without interrupting the advance of the ram, automatically retarding the ram movement to prevent forcible impact upon the work. Other objects of the invention will appear hereinafter.
In the drawing, Fig. 1 is a sectional elevation of a press embodying the invention;
Fig. 2 is a vertical sectional view of a portion of the press, upon a larger scale than Fig. 1 and with the ram shown advanced on its working stroke; and
Fig. 3 is an enlarged vertical section on the line 3-3 of Fig. 1.
The invention enables presses such as drawing presses and molding presses, for examples, to be operated at high speed with safety tothe work.
Under the automatic control of the improved ram control means the ram of a drawing press can be advanced rapidly to a point near the work and then automatically retarded, for gentle contact with the work. Thereby possible damage to the work by forcible impact is prevented. In the use of a molding press it is common to employ molding material in a powdered form and to compress such material in a mold by advance of the ram. Ordinarily, rapid advance of the ram would cause some of the powder to be blown from the mold so that a defective molded product would be formed. 'I'he improved ram control means provides for automatic slowing down of the advancing ram at a safe distance from the powdered charge so that cylindrical sneu s secured on end to the upper none of the charge will be blown from the mold.
Obviously the vinvention may be employed to advantage in presses used in other services where it is desired to safeguard the work from forcible impact by a ram or platen.
As shown. the press embodying the invention is of a vertical type and includes a frame structure comprising a lower transverse frame member or base I, a transverse upper frame member 2 and strain rods or columns 3 anchoring together. said frame members and supporting kthe upper member in a xed spaced relation the lower memside of said member. The frame member 2 has a vertical bore 6 in axial alinement with said shell and forming the lower portion of the cylinder.
A cylinder head casting 'I is secured to the upper end of the cylinder by vertical rods 8 anchored at their upper ends to the head and at their lower ends to the frame member 2 and holding the cylinderhead. the cylinder shell 5 and said frame member in assembled relation. A ram l has a piston head tted to reciprocate in the cylinder shell 5 and a shank extending downward from the piston head and outward through the lower end of the bore 6. At the lower end of the bore there is a stuiling box III and packing in which the ram is iitted to reciprocate. A compression plunger I I, for engagement with the work, is rigidly secured to the lower end of the ram.
Improved means for controlling movement of the ram are borne by the cylinder head 'I and the ram. Said head is formed with a vertical cylindrical chamber I2 inl axial alinement with the ram. Through a lateral bore I3 in the head, hydraulic pressure is supplied to the chamber and withdrawn therefrom. Bore I3 has a pipe connection I4 and by suitable means, not shown, pressure delivery and withdrawal through the pipe are controlled. Through a portv or passage I 5, formed in the cylinder head and coaxial with the ram and the chamber, the chamber I2 is normally in direct communication with the upper end of the press cylinder. Another communication between said chamber and the upper end of the cylinder is provided by a lateral bore I6 formed in the cylinder head and a vertical bore II extending downward from bore I6. A third communication between said chamber and cylinder is provided by a lateral bore I8 opening into an oblique bore I9. All of these bores are formed in the cylinder head. Below the point of communication of the bore I 8 with the bore I9 the latter bore is provided with a downwardly seating, ball check valve 20. A plug 2| is screwed into the upper end ofbore I! and bears a stop pin to limit opening movement of the ball valve. There is provided means operated by the ram to choke the port I6 upon a predetermined downward movement of the ram toward the work. Av
vertical rod 22 is secured at its lower end to the ram, on the-axis of the latter, and extends upward through the port I 5 and the chamber I2 and through a bore and counterbore at the upper side of the cylinder head. A choke plug 23 of tubular form is fitted over the rod I5 and has a down- 1 wardly tapered lower end 24., The untapered portion of the plug is of a size to t slidably within the port I5. 'I'he plug has an internal thread 25 screw-engaged with an external thread 26 on the rod 22 to render the plug adjustable along the rod. An internally threaded locking cap 21v is screwed upon the upper end of the rod to abut the upper end of the plug and retain an adjustment of the plug. Said cap and the upper end of the plug have flat outer sides for engagement by a Wrench. The adjusted and locked plug reciprocates with the ram, and the cylinder head-has a stuing box 28 and packing tting around the plug.
There is also means for restricting to a desired degree the communication between the chamber I2 and the press cylinder provided by the bores I6 and Il. A plug valve 29 is rotatably fitted within the bore I6 and has a beveled end 30 overlying the bore I1. By rotative adjustment of said valve the beveled end thereof is caused to obstruct the entrance to the port I1 to a desired degree. Bore I6 extends clear to an outer side of the cylinder head and is counter-bored. A bearing bushing 3| is secured within the outer encl oi the bore I6 and the valve has a stem 32 rotatably fitted in said bushing, protruding outwardly therefrom and provided with an operating handle 33. Said stem is screw-threaded and has a lock nut 34 screwed thereon to abut the outer end face of the bushing and lock the valve in an adjustment.
In preparation for operating the press the point, in the working stroke of the ram, at which the compression plunger will first engage the work is rst determined.. Then the tubular choke plug 23 is adjusted along the rod 22 relatively to the ram to such a position that in the descent of the ram the tapered end of the plug will begin to enter the port I5 shortly before the plunger reaches said determined point. The valve 29 is also adjusted to obtain a restriction of the bore I1 if desired. In the operation of the press, hydraulic pressure below the piston head of the ram is relieved through a pipe connection 35 at a low point in the press cylinder and hydraulic pressure is admitted to the press head chamber I2. From said chamber the hydraulic pressure at rst ows to the upper end of the press cylinder through the port I5 and also through the passage defined by the ports I6 and I1. Thereby the ram is advanced downward rapidly during a preliminary portion of its working stroke. As the plunger II approaches near to the work however, the tapered end 24 of the choke plug enters the port I5 and progressively chokes the port as the plug is moved downward with the ram until the untapered portion of the plug enters the port and closes-it entirely. The progressive choking of the port progressively reduces the rate of admission of hydraulic pressure to the press cylinder until nally such admission is solely through the bore I1. Thereby movement of the ram is retarded and the plunger II is brought gently into contact with the work.
Retraction of the ram is effected by relieving pressure through the pipe connection I4 and supplying hydraulic pressure through the pipe connection 35. At first the port I5 is choked by the plug 23. The passage defined by the bores I8 and I9 however provides a by-pass for quick relief of pressure at the top of the ram. During the downward movement of the ram by pressure in the chamber I2 said pressure holds the check valve 20 seated and thereby keeps said passage closed. When however, the pressure in the chamber is relieved and the ram is forced upward the check valve is unseated so that pressure at the tcp of the ram is quickly relieved by il'ow through said passage and also through the passage deilned by the bore I6 and I1. Withdrawal of the plug 22 from the port I5, by upward movement ot the ram, opens another passage for escape of pressure at the top of the ram. Therefore the pressure beneath the piston head of the ram, can retract the ram rapidly. Provision is thus made for rapid advance of the ram with safety to the work and the operator and also for rapid retraction of the ram.
What I claim is:
l. In a press having a ram and fluid pressure -means for advancing said ram on its working stroke, ram control means comprising means forming a fluid pressure chamber having a, port located on the axis of the ram to admit iiuid pressure from the chamber to said iluid pressure means for advance of the ram, a passage leading from said chamber to said iiuid pressure means to also admit fluid pressure to said means for advance of the ram, a rod borne by the ram to travel therewith and extending from the ram along the axis of the latter through said port with clearance around it within the port for said admission of fluid pressure, a tubular plug borne by said rod to travel therewith and fitting around the rod and tapering for progressive choking of the port as the ram is advanced to thereby retard advance of the ram by the uid pressure, means for adjusting said plug along the rod to vary the point in the ram stroke at which said plug becomes operative to choke the port, and manually adjustable means for restricting said passage tc a selected degree.
2. In a press having a ram and iiuid pressure means for advancing said ram on its working stroke, ram control meansa comprising means forming a iluid pressure chamber having a port located on the axis of the ram to admit fluid pressure from the chamber to said iluid pressure means for advance of the ram, a rod borne by the ram to travel therewith and extending from the ram along the axis of the latter through said port with clearance around it within the port for said admission of fluid pressure, a tubular plug borne by said rod to travel therewith and ltting around the rod and tapering for progressive choking of the port as the ram is advanced to thereby retard advance of the ram by the iluid pressure, and means for adjusting said plug along the rod to vary the point in the ram stroke at which said plug becomes operative to choke the port.
3. In a press having a ram and uid pressure means for advancing said ram on its working stroke, ram. control means comprising means forming a iiuid pressure chamber having a port to admit uid pressure from the chamber to said uid pressure means for advance of the ram, a passage leading from said chamber to said iluid pressure means to admit fluid pressure to said means for advance of the ram, a rod borne by the ram to travel therewith and extending from the ram through said port with clearance around it within the port for said admission of fluid pressure, a tubular plug borne by said rod to travel therewith and tting around the rod for choking of the portas the ram is advanced to thereby retard advance of the ram by the iluid pressure, and means for adjusting-said plug along the rod to vary the point in the ram. stroke at which said plug becomes operative to choke the port.
RICHARD W. DINZL.