US3859838A

US3859838A - Toggle actuated horizontal press

Info

Publication number: US3859838A
Application number: US350650A
Authority: US
Inventors: George D Karsnak
Original assignee: U S BAIRD CORP
Current assignee: U S BAIRD CORP
Priority date: 1973-04-12
Filing date: 1973-04-12
Publication date: 1975-01-14
Anticipated expiration: 1992-01-14
Also published as: JPS502271A; GB1394626A; JPS5633196B2

Abstract

A ram within a press head is driven through a toggle linkage to magnify the load applied thereto from peripheral shafts of a horizontal machine. The increased load is translated to the mounting bed of the machine through the housing of the press and, therefore, causes no distortion in the shaft. on advancing, the ram forces are applied to a knuckle joint which, except for friction therein, releases all bending moments in the members of the toggle linkage. A bell crank is incorporated for retracting the toggle linkage in a simplified manner.

Description

Unite a ps 13k Jan. 14, 1975 [54] TOGGLE ACTUATED HORIZONTAL PRESS 2,983,152 5/1956 Mitchell 72/451 [75] Inventor: George D. Knrsnak, Muncie, Ind. FOREIGN PATENTS 0R APPLICATIONS 73 Assigneei The & Baird Corporation, 611,566 7/1926 France 72/452 Strafford, Conn. Primary ExaminerC. W. Lanham. 122] Flledi 1973 Assistant Examiner-Gene P. Crosby [21] Appl. 50 5 Attorney, Agent, or FirmWooster, Davis & Cifelli [52] US. Cl 72/451, 10/11 R, 72/455, [57] ABSTR 100/281 100/292 rarn within a ress head 1s driven through a toggle [51] Int CL fi 9/18 linkage to magnify the load applied thereto from pc- [58] Fiend 450 ripheral shafts of a horizontal machine. The increased 10/11R,12 R, 11 A, 15, 16; 100/281, 292; 74/53 load is translated to the mounting bed of the machine through the housing of the press and, therefore, causes no distortion in the shaft. on advancing, the ram forces are applied to a knuckle joint which, except for friction therein, releases all bending moments in the members of the toggle linkage. A bell crank is incorporated=for retracting the toggle linkage in a simplified manner.

5 Claims, 5 Drawing Figures TOGGLE ACTUATED HORIZONTAL PRESS BACKGROUND OF THE INVENTION The present invention relates to a toggle linkage for a horizontal press head and especially to a toggle linkage including a bell crank for simplifying retraction. Hitherto, many different approaches have been taken to increase the operable loads of horizontal press heads which are driven from long shafts mounted peripherally on the fabricating machine. Loads are applied to such press heads through cam actuated linkages and the cams are affixed on the shafts. Because the shafts only transmit torsional power, the load applied to the press head is limited by the size of the shaft in that excessive loads will either wind up and/or bow the shaft along its length.

The most common approach is to actuate the ram directly from a bell crank with the ram being connected to one arm thereof and the cam driving a follower on the other arm thereof. With this approach, a mechanical advantage is only achieved by a favorable lever arm ratio which is limited by the natures of both the horizontal press head and the fabricating machine. Furthermore, any loads translated through the bell crank develop bending moments in the arms thereof and, therefore, these arms must be sized to preclude distortion therein when a mechanical advantage of any significance is developed.

Other approaches are utilized for achieving a mechanical advantage without a bell crank, however, springs are usually incorporated to retract the ram in these approaches. Because of the springs, the compactness of the horizontal press head must-be compromised and the effective mechanical advantage is reduced by the load required on the springs when advancing the ram.

SUMMARY OF THE INVENTION It is, therefore, a general object of the present invention to provide a horizontal press head which minimizes and obviates the disadvantages of the prior art.

It is a specific object of the present invention to provide a horizontal press head which is driven by a toggle linkage to severely reduce the bending moments encountered relative to the mechanical advantage developed thereby.

It is another object of the present invention to provide a horizontal press head having a toggle linkage which includes a bell crank for simplifying the retrac' tion thereof.

These objects are accomplished in one form according to the present invention by establishing a toggle linkage with a drive link pivotally jointed to a crank link at a knuckle joint. At the drive link end, the toggle linkage is pivotally affixed to a slideable 'ram, while at the crank link end it is pivotally affixed to a housing for the press head. The knuckle joint is driven by a cam on a peripheral shaft of the machine to extend the toggle linkage and where the use of springs is undesirable, a bell crank is incorporated as the crank link to retract the toggle linkage with the cam.

BRIEF DESCRIPTION OF THE DRAWINGS The mannerin which these and other objects of the invention are achieved will be best: understood by reference to .the following description, the appended claims, and the Figures of the attached drawings wherein:

FIG. 1 is a perspective view of a fabricating machine incorporating the horizontal press head of this invention;

FIG. 2 is a sectional view thereof, taken substantially along line 2-2 of FIG. 1 to illustrate the toggle linkage therein at the closed position of the ram;

FIG. 3 is a view similar to that of FIG. 2 illustrating the toggle linkage therein at the open position of the ram;

FIG. 4 is a vector diagram thereof illustrating the loads translated therein when the toggle linkage is oriented as shown in FIG. 2; and

FIG. 5 is a vector diagram thereof illustrating the loads translated therein when the toggle linkage is oriented as shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, a fabricating machine 10 for performing multiple press and forming operations is illustrated in FIG. 1 where an assemblage of individual attachments are coordinated on a mounting bed 12 to sequentially perform the operations required by a particular process plan. A stock feed attachment 14 is mounted at one end of the bed 12 and feeds stock 16 continuously along a process line A-A. Operating in conjunction with the stock feed attachment 14 is a stock check attachment 18 which locks the stock 16 in a fixed position along the process line A-A while the operations are performed thereon. Attachments for performing the operations are mounted on the bed 12 across the process line AA and, for the sake of simplicity only, are limited to a heavy duty press 20, a gang slide assembly 22 and a conventional slide 24. The detailed construction of the gang slide assembly 22 is not disclosed herein as it is disclosed and claimed in my copending application, Ser. No. 309,667, now US. Pat. No. 3,802,247. All attachments are actuated from drive shafts 26 which are mounted peripherally on the bed 12 and are supported therearound in corner brackets 28, with bevel gears (not shown) interconnecting therebetween at each corner. The timing sequence between all attachments is accomplished through the shafts 26 which are rotated by any :suitable means, such as a variable speed drive and a motor (not shown).

In the heavy duty press 20, a horizontal press head 30 is aligned across the stock 16 with a back plate 32 and is interconnected thereto by a bridge member 34, as illustrated in FIGS. 2 and 3. Conventional metal working tools, such as die sets (not shown) are securable to each side of the stock 16 on too] holders 36 (represented by phantom lines) which are affixed to both the horizontal press head 30 and the back plate 32. Bolts 38 are utilized to affix the bridge member 34 to both the horizontal press head 30 and the back plate 32, which in turn are each affixed to the bed 12 by bolts 40 passing through counterbored mounting holes 42 to engage nuts 44 disposed within T-slots 46.

The horizontal press head 30 is contained in a housing 48 to which a ram 50 is slideably retained and driven through a toggle linkage 52 from a cam 54. A

ram advance lobe 56 and a ram retract lobe 58 are disposed on the cam 54 which is affixed to one of the shafts 26 and rotated thereby. In accordance with the broad concept of such linkages, the toggle linkage 52 has a knuckle joint 60 pivotally interconnecting a drive link 62 to a crank line 64. A cam follower 66 is rotat ably disposed about the pivotal axis of the knuckle joint 60 and interfaces with the ram advance lobe 56 of the cam 54. From the knuckle joint 60, the drive link 62 extends to the ram 50 and is pivotally affixed thereto, while the crank line 64 extends to the housing 48 and is pivotally affixed thereto at a pivot point 68.

The housing 48 will vary in configuration depending on the mounting provisions of the bed 12, the means utilized for retaining the ram 50 thereto, the style of cam 54 utilized, and the particular arrangement of the shafts 26 on the machine 10. On the machine chosen for operation of the heavy duty press 20, the housing 48 is aligned on the bed 12 relative to both the process line A- A and the shafts 26 by a key 70 which is compatibly configured to engage the T-slots 46. Dovetail provisions 72 are incorporated into the housing 48 for retaining the ram 50 and a linkage chamber 74 is provided therein. Journal provisions 76 are disposed on the housing 48 for passing the shafts 26 through the linkage chamber 74 and include bearing caps 78 which are secured to the housing 48 with bolts 80 passing therethrough.

The ram 50 will vary in configuration depending on the means utilized to slideably retain it in the housing 48 and the manner by which it is pivotally connected to the toggle linkage 52. Since the housing 48 chosen to contain the horizontal press head 30 includes the dovetail provisions 72, the ram 50 includes compatible dovetail provisions 72' and a pivot block 82 is retained within a stroke adjustment chamber 84 thereof by a threaded collar 86. Suitable means, such as a pin 88, is utilized to pivotally affix the pivot block 82 to the drive link 62 and a reference block 90 is disposed at the bottom of the stroke adjustment chamber 84. Between the pivot block 82 and the reference block 90 is disposed a wedge block 92 which is rotatably affixed to a threaded stem 94. A locking nut 96 is engaged on the threaded stem 94 which screws through the ram 50.

Although the crank line 64 could be axially configured to merely extend between the pivot point 68 and the knuckle joint 60, it constitutes one arm 98 of a bell crank 100. A second cam follower 102 is rotatably affixed to the end of a second arm 104 on the bell crank 100 and interfaces with the ram retract lobe 58 on the cam 54.

When the heavy duty press is incorporated on the machine 10, the ram 50 operates between the closed position shown in FIG. 2 and the open position shown in FIG. 3. This is so because as the cam 54 is rotated counterclockwise by the shaft 26, the ram advance lobe 56 forces the cam follower 66 to raise the knuckle joint 60 and thereby the toggle linkage 52 is straightened to advance the ram 50 toward the stock 16. As cam rotation continues, the ram retract lobe 58 forces the second cam follower 102 to rise, which thereby turns the bell crank 100 counterclockwise and buckles the toggle linkage 52 to retract the ram 50 from the stock 16. An adjustment means for varying the relative stroke location of the ram 50 along an axis perpendicular to the stock 16 results from manipulation of the wedge block 92 between the reference block 90 and the pivot block 82. This is so because as the threaded stem 94 is turned, the wedge block 92 is effective to change the spacing between the reference block and the pivot block 82 and thereby changes the location of the stroke.

Incorporation of the toggle linkage 52 into the horizontal press head 30 is most significant because of the higher mechanical advantage achieved therewith relative to conventional drive linkages of horizontal press heads. The magnitude of the mechanical advantage can be appreciated from the vector diagrams of FIGS. 4 and 5 by observing the ratio of the ram load (F) to the cam load (P). As the toggle linkage 52 is straightened from the open position represented in FIG. 5 to the closed position represented in FIG. 4, the mechanical advantage increases greatly and theoretically approaches infinity. However, the loads in both the drive link 62 and the crank link 64 are increased in nearly direct proportion to the ram load and, therefore, a practical limit does exist to the mechanical advantage attainable with the toggle linkage 52. Another significant aspect of the toggle linkage 52 is that the increased mechanical advantage is accomplished by translating the increased loads to the housing 48 and, therefore, the bending moments in the dynamic components of the horizontal press head 30 are minimized. In fact, the only bending moments existing in the toggle linkage 52 are those resulting from friction in the knuckle joint 60 which otherwise turns to release any bending moments. Because of the relatively minor bending moment in both the drive link 62 and the crank link 64, these members are reduced in size relative to the bell crank type of linkage normally utilized in conventional horizontal press heads to develop the same mechanical advantage for identical applications.

By utilizing the arm 98 of the bell crank as the crank link 64, a problem normally encountered with toggle linkages is resolved. Very generally stated, this problem arises after the toggle linkage has been actuated to a straightened position and is useless thereafter until returned to a buckled position. In many applications springs are incorporated to store energy when the toggle linkage is straightened and thereafter to release the energy in returning the toggle linkage to a buckled position. However, the use of such springs in the horizontal press head 30 would only defeat one primary feature of the invention because of the reduced mechanical advantage caused thereby and, furthermore, would complicate the compatible configuration existing between the ram 50 and the housing 48. Therefore, by providing both the crank link 64 of the toggle linkage 52 and a means for returning the toggle linkage S2 -to its buckled position, the bell crank 100 maximizes the mechanical advantage attained, while simplifying the construction of the horizontal press head 30.

It should be readily appreciated by those skilled in this art that the toggle linkage of this invention may be employed within a horizontal press head to achieve a mechanical advantage without encountering severe bending moments in the dynamic components thereof. Furthermore, the crank link of the toggle linkage may be incorporated as an arm on a bell crank to. maximize the mechanical advantage attained and simplify the structure of the horizontal press head.

It should be understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination or arrangement of parts may be resorted to without departing from the true spirit and the scope of this invention. Therefore, the present disclosure should be construed as illustrative rather than limiting.

I claim:

1. A press head for operating across a process line on a metal fabricating machine, comprising:

a housing including means for detachably securing to the machine;

a ram slideably retained in said housing; and

a toggle linkage between said ram and said housing,

said toggle linkage having a drive link and a crank link interconnected at a knuckle joint, said drive link extending from said knuckle joint to said ram and being pivotally affixed thereto, said crank link extending from said knuckle joint to said housing and being pivotally affixed thereto, said ram being advanced when forces are applied at said knuckle joint to straighten said toggle linkage, said knuckle joint moving within said toggle linkage to release bending moments in said drive link and said crank link, said toggle linkage developing a mechanical advantage to deliver magnified forces at said ram.

2. The press head of claim 1 wherein said crank link is one arm of a bell crank, said bell crank being pivotally affixed to said housing and being pivotal to buckle said toggle linkage in response to bending moments translated through the second arm thereof.

3. In a metal fabricating machine of the type wherein attachments are organized on a mounting bed and actuated from shafts peripheral thereto in performing a sequence of operations according to a process plan on stock fed along a process line extending through all operations, the improvement comprising:

a press head having a toggle linkage connected between a housing and a ram, said housing including means for detachably securing; to the machine, said ram being slideably retained in said housing, said toggle linkage having a drive link and a crank link interconnected at a knuckle joint, said drive link extending from said knuckle joint to said ram and being pivotally affixed thereto, said crank link extending from said knuckle joint to said housing and being pivotally affixed thereto, said ram being advanced when said toggle linkage is straightened by forces applied at said knuckle joint from a cam on one peripheral shaft, said knuckle joint moving within said toggle linkage to release bending moments in said drive link and said crank link, said toggle linkage developing a mechanical advantage to deliver magnified forces at said ram.

4. The metal fabricating machine of claim 3 wherein said crank link is one arm of a bell crank, said bell crank being pivotally affixed to said housing and being pivotal to buckle said toggle linkage in response to bending moments developed through the second arm thereof from forces applied by the cam.

5. In the combination of claim 1 wherein complementary dovetail provisions are disposed between said ram and said housing to achieve slideable affixment therebetween.

Claims

1. A press head for operating across a process line on a metal fabricating machine, comprising: a housing including means for detachably securing to the machine; a ram slideably retained in said housing; and a toggle linkage between said ram and said housing, said toggle linkage having a drive link and a crank link interconnected at a knuckle joint, said drive link extending from said knuckle joint to said ram and being pivotally affixed thereto, said crank link extending from said knuckle joint to said housing and being pivotally affixed thereto, said ram being advanced when forces are applied at said knuckle joint to straighten said toggle linkage, said knuckle joint moving within said toggle linkage to release bending moments in said drive link and said crank link, said toggle linkage developing a mechanical advantage to deliver magnified forces at said ram.

3. In a metal fabricating machine of the type wherein attachments are organized on a mounting bed and actuated from shafts peripheral thereto in performing a sequence of operations accOrding to a process plan on stock fed along a process line extending through all operations, the improvement comprising: a press head having a toggle linkage connected between a housing and a ram, said housing including means for detachably securing to the machine, said ram being slideably retained in said housing, said toggle linkage having a drive link and a crank link interconnected at a knuckle joint, said drive link extending from said knuckle joint to said ram and being pivotally affixed thereto, said crank link extending from said knuckle joint to said housing and being pivotally affixed thereto, said ram being advanced when said toggle linkage is straightened by forces applied at said knuckle joint from a cam on one peripheral shaft, said knuckle joint moving within said toggle linkage to release bending moments in said drive link and said crank link, said toggle linkage developing a mechanical advantage to deliver magnified forces at said ram.