US3481592A

US3481592A - Center post guided die cushion assembly

Info

Publication number: US3481592A
Application number: US699493A
Authority: US
Inventors: John Hoenig
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-01-22
Filing date: 1968-01-22
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02

Description

Dec. 2, 1969 J. HOENIG CENTER POST GUIDED DIE CUSHION ASSEMBLY Filed Jan. 22, 1968 VENTOR.

A| P||. a 1A 4 wbr/www. IMHHIIHMU, A1; @Half Y W @MMM WAH /y/ f4 M! .rw ,4 if l /fH/ i .lvwdwwwvm INAVITIMANIHIIH l lill IJIII. i j V 1Q z /l l 1V l M Il United States Patent O U.S. Cl. 267--1 4 Claims ABSTRACT OF THE DISCLOSURE A center post guided die cushion assembly for a press or the like. The center post is supported by a plate that is aixed across one end of a pocket that contains the die cushion assembly and that lies beneath the press bolster plate. The center post extends concentrically through the cushioning cylinder and slidably guides the reciprocating movement of the piston.

BACKGROUND OF THE INVENTION This invention relates to an improved center post guided die cushion assembly for a press or the like.

The use of air or hydraulic die cushions for applying pressure to the die blank holder or pad of a press are well known. With this type of construction, pressure is generally applied from the piston of the die cushion to the respective press component through die or pressure pins. Since the pistons of these cushions experience considerable loading, it is essential that their movement be guided over a relatively large area to preclude any binding under the load and attendant damage to the die cushion. Although it previously was proposed to guide such pistons at the area of contact between the piston and cylinder, this method of guiding has several defects. The primary defect in such a guiding arrangement is that the -piston seals are subjected to considerable loading resulting in premature failure. It, therefore,` has been more recently proposed to employ a center post guiding arrangement for the piston. With this type of die cushion assembly, a center post extends coaxially through the cylinder and slidably supports the piston. In such a construction, it is necessary to insure a rigid support for the upper end of the center post. Such support was heretofore provided by directly attaching this center post to the bolster plate of the press, but this also has certain disadvantages. If the center post is `directly connected to the bolster plate, setup is diflicult and more time consuming, In addition, the die cushion must be relocated every time the bolster plate is changed, which can occur frequently. There is also considerable difliculty in correctly locating the bolster plate with respect to the die pocket and other components of the press which can result in binding of the die cushion center post.

It is, therefore, a principal object of this invention to provide an improved center post guided die cushion assembly.

It is another object of this invention to provide a center -post guided die cushion assembly wherein the center post is supported independently of the lbolster plate of the press.

BRIEF SUMMARY OF THE INVENTION A center post guided die cushion assembly embodying this invention is adapted to be supported as a unit in a pocket beneath the bolster plate of a press or the like. The die cushion assembly comprises a cylinder defining a cylinder bore in which a Ipiston is reciprocally supported. A support plate is adapted to extend across the die cushion pocket and is adapted to be xed to the press or the like. A center post is affixed at one of its ends to the support plate. The center post extends into 3,481,592 Patented Dec. 2, 1969 the cylinder bore and is affixed at its other end to the cylinder. Means on the center post and on the piston guide the piston and cylinder for relative reciprocation independently of the cylinder bore.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a longitudinal cross sectional View of a portion of a press incorporating a center post guided die cushion embodying this invention and taken generally along the line 1-1 of FIGURE 2;

FIGURE 2 is a top plan view of the press shown in FIGURE 1, with the bolster plate removed to more clearly show the construction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the reference numeral 11 indicates generally a center post guided die cushion assembly embodying this invention. The die cushion assembly 11 is particularly adapted for use in presses, which may be of any known type. The press, which is illustrated partially in the drawings, includes a bolster plate 12 that overlies a die cushion pocket 13 formed in the base of the press by means of a pair of vertically extending

plates

14 and 15 that are aii'ixed to cross plates 16 and 17. An upper plate 18 extends across the

plates

14, 15, 16 and 17 and serves to provide support for the lbolster plate 12. In ya like manner, a bottom plate 19 extends across the lower edge of the

plates

14, 15, 16 and 17 and at least partially across the lower end of the die cushion pocket 13.

Referring now to the construction of the die cushion assembly 11, it is comprised of a cylinder 21 that defines a cylinder bore 22 that is open at its upper end and which is closed at its lower end by an integral end wall 23. The cylinder end wall 23 is connected in any suitable manner to a supporting base 24. The supporting base 24 is affixed with respect to the press plate 19 by means of socket headed bolts 25.

A piston 26 is supported for reciprocation within the cylinder bore 22. The piston 26 carries an annular seal 27 at its lower end to provide a uid tight seal between the piston 26 and the cylinder bore 22. The extreme upward position of the piston 26 within the cylinder bore 22 is limited 'by an annular stop ring 28 that is aflixed to the upper end of the cylinder 21 by means of socket headed bolts 29.

The piston 26 defines a hub or pilot portion 31 that has cylindrical bore 32. Antifriction bushings 33 and 34 are xed in circumferential recesses 35 and 36, respectively, formed at opposite ends of the bore 32. A center post 37 extends upwardly through the bore 32 and slidingly engages the bushings 33 and 34 to guide the reciprocation of the piston 26. The lower end 0f the center post 37 extends through an opening 38 in the cylinder wall 23 and is hield in :place by a nut 39 that is threaded onto its tapped lower end 41.

In die cushions of the type described, the seal 27 of the piston vdoes not take any of the guiding forces of the piston 26 and thus, this seal is not subjected to any undue wear since the center post 37 accomplishes the guiding function. With this type of assembly, it previously had been the practice to support the upper end of the center post through a direct connection to the bolster plate 12 of the press, which as has been noted, requires relocation of the upper center post support when the bolster plate 12 of the press is changed. Certain other disadvantages also are attended with the upper support of the center post by the bolster plate. In the described die cushion, the center post 37 is supported at its upper end independently of the bolster plate 12 in a manner now to be described.

The upper end of the center post 3'7 is formed with a bored opening 42 that receives a pilot portion of a top support plug 43. The support Iplug 43 is fixed, as by bolts 44 to an upper support plate 45 that extends across the upper end of the die cushion pocket 13. The plug 43 also may have a :pilot portion that fits into a bored hole in the support plate 45. The plate 45 is accurately located with respect to the press assembly and when so located is xed in position by socket headed bolts 46 that are threaded into supporting blocks 47 which are, in turn, fixed to the

respective plates

14 and 15 of the press assembly. This construction permits accurate location of the upper support for the center post 37 and permits the center post 37 to be supported at its upper end independently of any direct connection to the bolster plate 12.

The piston 26 is abuttingly engaged at its upper end by a pressure plate 51. The pressure plate 51 is contacted by pressure or die pins 52 of the press which pins extend through bores 53 formed in the bolster plate and like bores 54 formed in the top supporting plate 45. As is well known in this art, the pressure exerted by the piston 26 is transmitted through the pressure plate 51 to the pins 52 and to the corresponding component of the press. Hydraulic or pneumatic pressure for this purpose is introduced to a cavity 55 formed between the piston 26 and cylinder bore 22 by means of a pressure conduit 56.

In order to lubricate the bushings 33 and 34, transversely extending lubricating passages 57 and 58 are formed in the center post 37. The passages 57 and 58 are intersected by an axially extending passage 59 that opens through the lower end of the center post 33. Any suitable lubrication pressure conduit may be connected to this lower end of the passage 59 for lubrication of the bushings 33 and 34.

`In order to preclude the ingress of chips, dirt or other foreign matter onto the piston seal 27, a cylindrical shroud ring 61 is affixed to the pressure plate 51 in any suitable manner. The shroud ring extends downwardly closely adjacent the outer periphery of the stop ring 28 and upper edge of the cylinder 21. In the uppermost position of the piston 26 as illustrated in FIGURE l, this shroud ring depends slightly below the aforenoted elements. Hence, a labyrinth type seal is provided for precluding the entry of foreign matter onto the moving components of the cushion assembly 11. In addition, downward movement of the pressure plate 51, piston 26 will cause a decrease in the volume 62 between the shroud ring 61 and piston 26 above the stop ring 28. Hence, air will be driven from the area 62 tending to drive out any foreign particles which may have entered past the shroud ring 61.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modication, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A center post guided die cushion assembly adapted to be supported as a unit in a pocket beneath the bolster plate of a press or the like without any direct connection to the bolster plate, said die cushion assembly comprising a cylinder dening a bore, a piston reciprocally supported in said cylinder bore, a support plate adapted to extend across one end of the die cushion pocket and adapted to be afixed to the press or the like, the center post aixed at one of its ends to said support plate, said center post extending into said cylinder bore, means for aixing the other end of said center post relative to said cylinder, and means on said center post and on said piston for guiding the reciprocation of said piston within said cylinder bore substantially independently of said cylinder bore.

2, A center post guided die cushion assembly as set forth in claim 1 wherein the center post has a pilot portion received in a bore in the support plate for assisting ir locating said center post with respect to said support p ate.

3. A center post guided die cushion assembly as set forth in claim 1 wherein the support plate is positioned adjacent the press bolster plate and is affixed in an accurate location with respect to the pocket for permitting interchange of the bolster without necessitating relocation of the support for the one end of said center post.

4. A center .post guided die cushion assembly as set forth in claim 1 wherein the cylinder is open at its upper end, and further including a shroud ring aixed for reciprocation with the piston, said shroud ring being juxtaposed to said open end of said cylinder and extending downwardly therefrom when said piston is in its extreme upper position, movement of said piston and said shroud ring downwardly being effective to drive foreign particles from the volume surrounding said piston.

References Cited UNITED STATES PATENTS JAMES B. MARBERT, Primary Examiner