US3580794A

US3580794A - Stamping press with linearly applied force

Info

Publication number: US3580794A
Application number: US765557A
Authority: US
Inventors: Leonard A Mintz
Original assignee: LEONARD A MINTZ
Current assignee: LEONARD A MINTZ
Priority date: 1968-10-07
Filing date: 1968-10-07
Publication date: 1971-05-25
Anticipated expiration: 1988-05-25
Also published as: GB1227640A

Abstract

A STAMPING PRESS HAVING AN AIR CYLINDER WHICH TRANSFERS ITS FORCE TO A STAMPING HEAD BY MEANS OF A WEDGE FORCED BY THE AIR CYLINDER BETWEEN A REACTION ROLLER AND A RAM DRIVING THE STAMPING HEAD. DURING THE APPROACH STROKE, ONE PLANAR FACE OF THE WEDGE IS AT A SUBSTANTIAL ANGLE TO THE AXIS OF THE PISTON OF SAID AIR CYLINDER, BUT DURING THE PRESSURE STROKE ANOTHER PLANAR FACE OF THE WEDGE IS DISPOSED AT A VERY SMALL ANGLE TO THE PISTON AND IT EXERTS ITS PRESSURE SUBSTANTIALLY SOLELY ALONG THE AXIS OF TRAVEL OF THE STAMPING RAM. THE PRESS ALSO HAS A HAND LEVER TO ROTATE THE AIR CYLINDER AND WEDGE ABOUT AN AXIS TO PERMIT HAND OPERATION OF THE RAM. WHEN USED FOR ROLL LEAF STAMPING A LINEAR THRUST DRIVE IS COUPLED TO THE ROLL LEAF TO ADVANCE IT IN THE SAME DIRECTION UPON BOTH DIRECTIONS OF MOTION OF SAID THRUST DRIVE.

Description

L. A. MINTZ STAMPING PRESS WITH LINEARLY APPLIED FORCE Filed Oct. 7, 1968 4 Shoots-Shoot 1 INVENTOR LEONARD A. MINTZ By MM Q TTORIVE Y Ma 25, 1971 L. A. MINTZ 3,580,794

STAMPING PRESS WITH LINEARLY APPLIED FORCE Filed Oct. 7, 1968 4 Sheets-Sheet 2 F/G. 2 I

INVENTOR LEONARD A. MINT? ATWRNEY May 25, 1971 L. A. MINTZ Filed Oct. '7. 1968 STAMPING PRESS WITH LINEARLY APPLIED FORCE 4 Sheets-Sheet 5 f er TORNEY May 25, 1971 N z 3,580,794

STAMPING PRESS WITH LINEARLY APPLIED FORCE Filed 001.. '7, 1968 i I 4 ShOOtS-ShOQt 6 INVENTOR LEONARD A. M/NTZ B @0960 ATTORNEY United States Patent O US. Cl. 156-581 6 Claims ABSTRACT OF THE DISCLOSURE A stamping press having an air cylinder which transfers its force to a stamping head by means of a wedge forced by the air cylinder between a reaction roller and a ram driving the stamping head. During the approach stroke, one planar face of the wedge is at a substantial angle to the axis of the piston of said air cylinder, but during the pressure stroke another planar face of the wedge is disposed at a very small angle to the piston and it exerts its pressure substantially solely along the axis of travel of the stamping ram. The press also has a hand lever to rotate the air cylinder and wedge about an axis to permit hand operation of the ram. When used for roll leaf stamping a linear thrust drive is coupled to the roll leaf to advance it in the same direction upon both directions of motion of said thrust drive.

BACKGROUND OF THE INVENTION High-powered stamping presses are used for various types of stamping processes. Particularly in those which are used in hot leaf stamping for marking and decorating, it is necessary to have a very close control of the force exerted by the stamping head at the surface of the article to be marked. Slight variations in such pressure have a markedly deleterious elfect on the quality of the work. In machines of this kind where the pressure force required is of the order of tons, this force may be obtained from an air operated pressure cylinder. However, it would be inordinately expensive to employ a long stroke slow acting air cylinder to generate and impress its force directly onto the stamping head. Since the maximum pressure is required only within a very small distance at the end of the stamping stroke, the large amount of air used to actuate the cylinder during the major part of the stroke is wasted. The result is the use of inordinately large and expensive air compressors. As a result, most compressed air operated stampin-g presses use some kind of force multiplying linkage between the piston of the air cylinder and the ram driving the stamping head. Typical of such linkages have been knuckles or toggles. One difiiculty with such linkages is that the amount of force exerted by the stamping head varies continually along its stroke. This is particularly deleterious at the point where the stamping surface contacts the surface of thework piece. Slight variations in the thickness of the work pieces, which are normally encountered, produce substantial variations in the stamping pressure. This in turn causes variations in the quality of the stamping produced, resulting in a substantial percentage of unacceptable work pieces. Attempts at meticulous adjustments in the air pressure controls and in the control of the sizes and supports of the work pieces are at best expensive and only partially effective. An additional difficulty in such prior 3,530,794 Patented May 25, 1971 "ice machines is that the force multiplying linkage exerts its force on the ram so that there is a substantial component of force exerted transverse to the direction of travel of the ram, in addition to the desired force exerted along such direction of travel. As a result, excessive wear is produced between the ram and the ways or gibs in which it travels. Such wear requires very frequent readjustments of the alignment of the machine in order to produce acceptable uniformity in the work product and also frequent and expensive replacements of worn rams and ways.

The present invention eliminates both of the above difficulties as well as creating additional advantages. It does so by a novel arrangement of a force multiplying transformation interposed between the piston of the air cylinder and the pressure ram providing two constant pressure ranges throughout the entire length of the stroke. During the final, or working portion of the stroke, the working pressure is exerted upon one end of the pressure ram solely in a direction along the path of travel of said ram, with no transverse component of force. During this working portion, the force multiplication factor between the force within the air cylinder and the force exerted on the work piece remains constant thus eliminating the problems in variations in work due to slight variations in the exact point in the travel of the ram at which stamping actually occurs.

SUMMARY OF THE INVENTION This invention accomplishes the desired results described above by disposing the air cylinder so that its piston moves along a line which deviates from a right angle relationship with the direction of travel of the pressure ram by a very small angle, which may be of the order of 5. That piston has mounted firmly at its outer end a wedge whch is forced, by the piston, between a stationary reaction roller and a roller mounted on one end of the pressure ram. The outer end of the wedge is provided with a planar wedge surface disposed at a substantial angle with respect to the direction of travel of the piston, so that such surface moves the ram carrying its stamping head rapidly towards the work with a constant pressure exerted on the ram. As the stamping head moves into the region of its pressing operation, a second planar surface on the wedge enters the space between the reaction roller and the ram roller. That second surface is disposed at the same angle with respect to the direction of travel of the piston as that existing between the direction of travel of the piston and perpendicular to the line of travel of said ram, which angle, as has been indicated above, may be of the order of 5. The smallness of such angle produces a very large amplification of the force exerted by the air cylinder, but at the same time, the equality between the angles described above causes that amplified force to be exerted solely along the direction of the pressing stroke, and with substantially no lateral component. As indicated above, this arrangement results in an extraordinarily effective operation which eliminates the previous difficulties of undesirable variation in working pressures and excessive wear. This arrangement also permits the ram to be hand-operated by manually rotating the air cylinder together with the wedge about an axis transverse to the normal direction of motion of the piston.

In addition, when the invention is used in a roll leaf stamping machine, it may be provided with a special pneumatic cylinder drive for a roll which advances the roll leaf through the machine. Such drive operates through a pair of gears coupled respectively to said roll through oneway clutches. These gears are driven by a pair of racks moved back and forth by its pneumatic cylinder and related to the gears so that the roll advances the roll leaf in the same direction for both parts of the stroke thus greatly reducing the necessary length of such stroke.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be best understood by referring to the annexed drawings in which:

FIG. 1 is a vertical cross-section of an embodiment of any novel machine, taken along line 11 of FIG. 2;

FIG. 2 is a front view of the machine shown in FIG. 1;

FIG. 3 is a transverse cross-section taken along line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary cross-section taken line 44 of FIG. 3;

FIG. 5 is a fragmentary cross-section taken along line 5- 5 of FIG. 4;

FIG. 6 is a diagrammatic enlarged view showing successive positions of the force multiplying wedge as it moves between the reaction roller and the roller carried by the pressure ram; and

FIG. 7 is a smaller diagrammatic view of another embodiment of the wedge.

DESCRIPTION OF THE PREFERRED EMBODIMENT The embodiment of my invention as shown in the drawing is constructed with a main frame 1 made up of two generally C shaped

side plates

2 and 3. Each of these plates are stiffened and reinforced by a rib 4 welded along the rear and bottom edges of the plates and by a rib 5 welded along the edges of the plate at its C shaped opening. The two

plates

2 and 3 are joined together to form the main frame 1 by means of

transverse plates

6, 7, 8 and 9, each welded to both

plates

2 and 3.

In order to support the work to be stamped, the machine is provided with a work table 10 carried at the upper end of a dovetail shaped ram 11 which is slidably mounted between a bearing plate 12, fastened to the transverse plate 9, and a pair of gibs 13 held in place by a pair of brackets 14 which are secured by bolts 15 which are threaded into the bearing plate 12. The gibs 13 are located between the side arms of a U-shaped frame 16 mounted at the lower front portion of the main frame 1. The work table 10 may be raised and lowered to any desired position by means of an elongated screw 17 rotatably fastened to the lower end of ram 11 and threaded through a threaded bushing 18 secured in the transverse portion 19 of the U-shaped frame 16. The screw 17 may be rotated by a handle 20 fastened to its lower end.

This embodiment is adapted to stamp letters, characters or other design in metallic or pigmented foil upon Workpieces supported on the work table 10. Such stamping operation is performed by a stamping head 21 carried on the lower end of an upper dove-tail ram 22 which is slidably mounted between a bearing plate 23, supported on the transverse plate 6, and a pair of gibs 24 held in place by bolts 26 which pass through the gibs 2 4 and the bearing plate 23 and are threaded into the transverse plate 6. The bearing plate 23 is held in the proper position by a pair of dowels 27 press-fitted into the plate 6. These dowels project into a transverse slot which extends across a major portion of bearing plate 23 and thus retain said plate in position. Fine adjustments in the positioning of the gibs 24 are provided by adjusting bolts 34, threaded through

side plates

2 and 3 and bearing on the outside faces of the gibs 24.

The stamping head 21 is heated in any Well-known manner to heat a stamping die 29 of any desired configuration and carried by said stamping head 21. Below the die 29 is mounted a strip of stamping leaf 30, which may be any well-known type such as a plastic strip coated on its lower surface with a metallic foil which is to be impressed on the work by the heated die. The strip of stamping leaf 30 is supplied from a roll 31 carried by a bracket 32 mounted on a frame 33 preferably mounted on and carried by the stamping head 21. As the strip 30 comes off the roll 31 it passes under a pair of

springtensioned rollers

63 and 66, also carried by the frame 33 and is pulled through the machine by means of a pair of

foil feed rollers

69 and 70, the construction and action of which will be described in more detail later.

The ram 22 is power operated by means of a wedge 37 forced between a roller 38 mounted on the upper end of ram 22 and a reaction roller 39, rotatably mounted between a pair of arms 40 depending from a crossbar 41 bolted firmly in place by bolts 42 on lugs 43 formed on the upper ends of

side plates

2 and 3. The wedge 37 is power activated by a pneumatic cylinder 44 whose internal piston 44a is connected to a thrust rod 45 fastened to the wedge 37. Compressed air at high pressure is supplied to the cylinder 44 through a high pressure hose 46 from a controlled source of compressed air (not shown) by any of the well-known mechanisms commonly used in the art of roll leaf stamping machines. The cylinder 44 in combination with the wedge 37 is pivotally mounted by means of a sturdy pivot bar 47 on each side of the head 35 of the cylinder 44, which bars 47 are carried by and journalled in side plates 2. and 3.

The pivot bars 47 are located at such a location on

side plate

2 and 3 so that the axis of the cylinder 44, which determines the direction of motion of the thrust rod 45, forms a small angle, which may be of the order of a few degrees (e.g. five degrees), with the horizontal. In addi tion to a top operating face 53, the wedge 37 is provided with two operating faces 48 and 49. The upper operating face 48 is located at a substantial angle with respect to the axis of the cylinder '44 (e.g. about 45). With a 45 disposition of the face 48, the pressure applied vertically to the roller 38 is substantially equal to the pressure applied by the cylinder 44. While the roller 38 rides along the face 48, there is a component of pressure which is exerted horizontally against that roller as Well as in the vertical direction. However, this is the approach portion of the stroke and the die 29 is not permitted to contact the work on the table 10 until the roller has passed from the face 48 to the face 49. Since during the approach portion of the stroke the air pressure in cylinder 44 does not build up to full value, such horizontal or transverse pressure on the roller 38, and therefore on the ram 22, is not sufficient to cause any deleteriou transverse flexing or wear on the ram structure. By selecting any desired value for the angular disposition of the face 48, the length of the approach stroke as compared with the distance of travel of the piston in the cylinder 44 can be, within relatively wide limits, of any desired value. The stamping head 21 is biased in an upward direction in any desired manner, preferably by means of two pairs of

springs

54 and 55. The lower end of each of springs 55 is secured to a rod 57 carried by and projecting from the opposite side of head 21. The upper ends of

springs

54 and 55 are secured respectively to a pair of rods 58 and 59 canied by and projecting from a pair of

levers

60 and 61 pivoted at their lower ends respectively in

side plates

2 and 3. Each of the

levers

60 and 61 is provided with a handle 62 so that the

levers

60 and 61 may be manually rotated from the upper position shown in FIG. 2 to a lowered position in which the tensions on the

springs

54 and 55 are released and the stamping head 21 may be moved manually in setting up the work on the table 10 to produce the proper alignment between the work and the stamping die 29. When the

levers

60 and 61 are returned to their upper position, tension is restored to

springs

54 and 55 and the head 21 carrying the ram 22 with its roller 38 are moved upward until the roller 38 contacts the forward end of the wedge 37 along the face 48.

The relationships between the wedge 37 and the

rollers

38 and 39 may be better understood by referring to FIG. 6 which shows the wedge moving from an initial position I to successive positions II and III, while the roller 38 moves to corresponding positions I, II and III. With the ram 22 mounted to move along a vertical path, as shown in the drawings, the centers of the

rollers

38 and 39 are located along a vertical center line 50. The direction in which the thrust rod 45 moves the wedge 37 is along the line 51 which forms a small angle with the horizontal 52. The upper planar surface 53 of the Wedge 37 may be parallel (but not necessarily so) to the line 51, while the face 49 is located along the horizontal. Thus the face 49 forms a small angle with the direction of travel of the wedge 37 and that small angle is substantially equal to 5 As previously indicated, this small angle is preferably only a few degrees, e.g. 5. The size of the angles and is determined by the amount of pressure multiplication desired between the pressure exerted by thrust rod 45 and the pressurse to be exerted between the stamping head 21 and the work on table 10. The greater the desired multiplication, the smaller will be and while the smaller the desired multiplication, the larger will be qb and 5 The face 48 is disposed at any desired angle a with respect to the direction of travel 51 of the wedge 37 and, as previously indicated, may be of the order of 45. The size of angle is determined by the degree of motion multiplication desired between the motion of the thrust rod 45 and the motion of the ram 22. The larger the desired movement of the ram 22 with respect to the movement of the thrust rod 45, the larger will be 5 The smaller the desired ratio between these two movements, the smaller will be For a value of of 45, when thrust rod 45 moves one unit of distance, the roller 38 and thus the ram 22 will also move one unit of distance. Instead of the plane of surface 53 being parallel to the line 52, it could be disposed at an angle with respect thereto, as long as that angle is not equal to during the portion of the stroke in which surface 49 rides on roller 38, in which case surface 53 would be parallel to surface 49 and no vertical motion of roller 38 would occur as surface 49 moves across said roller. However, the preferred disposition of surface 53 during said portion of the stroke is parallel to the line 51. Also, as indicated in FIG. 7, the surface 53 could be divided into two planar surfaces 53a and 53b which join each other at the point where the roller 38 moves from surface 48 to surface 49, thus providing two planar surfaces corresponding to

surfaces

48 and 49 respectively. The angular disposition of the plane of 53a, corresponding to surface 48, could be virtually any desired value. However, as stated above, the preferred embodiment is a single plane for surface 53 lying parallel to line 51.

As the wedge 37 moves from position I to position 11 and the roller 38 moves correspondingly from position I to position II, we see that a relatively large travel is imparted to roller 38. During this travel one component of pressure is exerted on roller 38 downward along the vertical direction 50 and a substantially equal component of force is exerted transversely on the roller 38 in a horizontal direction. With the 45 relationship, this vertical pressure is substantially equal to the pressure exerted by the thrust rod 45. However, during this portion of the stroke of the ram 22, which is the portion during which the stamping head 21 carrying the die 29 approaches, but does not contact the work, there is only a comparatively small amount of pressure exerted on the roller 38 suffi cient merely to move the ram 22 and its associated structure downwardly against the tensions of the

springs

54 and 55. Therefore, the fact that a correspondingly small transverse pressure is exerted against the roller 38 does no harm.

Just before the Work is contacted, the roller 38 moves oif face 48 and moves onto face 49. The wedge 37 now moves to position III and the roller 38 moves to its corresponding position III where it is stopped by the fact that the die 29 has contacted the Work preventing further downward movement of the roller 38. It should be noted that, due to the angular relationships described, the face 49 moves substantially solely in a vertical direction throughout the time it is in contact with roller 38. Therefore, its pressure is exerted against the roller 38 substantially solely in a vertical direction so that there is virtually no transverse component of pressure exerted against the roller 38. The pressure exerted during this operation is quite large. 'For example, using a 3 /2 inch bore for the cylinder 44 with an air pressure of p.s.i. and with the 5 disposition of angle the pressure exerted vertically by the mm on the work is 10,000 pounds. Using a 4 /2 inch bore cylinder and with the same air pressure, somewhat in excess of 7 /2 tons will be applied to the work by the ram. It will be recognized that with pressures of such magnitudes, any substantial component of the pressure which is exerted transversely against the roller 38 will exert a large bending force on the ram 22 tending to make it bind in its gibs and producing large amounts of wear between the ram and its gibs. Such bending force also tends to produce misalignments between the stamping head and the works resulting in undesirably nonuniform stamping results. The translations of the pressures exerted by the cylinder 44 through the wedge 37 necessarily result in a transverse component of pressure. However, that is absorbed substantially entirely by the reaction roller 39. Any bending, twisting or wear in the structure associated with roller 39 has virtually no effect on the operation. The position of the roller 39 is not at all critical and its shaft and associated bearing surfaces can undergo large amounts of wear without adverse effects on the operation. Also, it is very easy and inexpensive to replace the roller 39 as compared with any replacement of the structure of the ram 22.

Due to the planar relationships described, the multiplication between the pressure exerted by the thrust rod 45 and the pressure exerted upon the work is due solely to the magnitude of the angle and not upon the position of the head along its direction of travel, as occurs in prior machines of this general kind. Therefore, it makes little, if any, difference on the resulting work at what point the die 29 actually contacts the work. Thus, variations in the thickness of the work or in the level at which it is supported do not alter the stamping pressure. The result is that such variations, which are intolerable in such other machines, are easily and adequately handled by the present machine with excellent results.

The die 29 exerts its pressure upon the work through the stamping leaf 30 which is interposed between the die 29 and the work. The stamping stroke transfers some of the metallic foil from the leaf 30 and therefore, between each stamping stroke, the leaf 30 must be advanced through the machine so as to present a fresh strip beneath the die 29 for the subsequent stamping stroke.

As the leaf 30 comes off the roll 31 it passes under a roller 63, the ends of which are journalled in the ends of a pair of spring pressed rods 64, only one of which can be seen in FIG. 2, each of which is mounted in a hole in frame 33 and biased downwardly by a spring 65. The leaf r30 continues beneath the die 29 and under a second roller 66, the ends of which are journalled in the ends of a pair of spring pressed rods 67 (both of which can be seen in FIG. 1). Each of the rods 67 is mounted in a hole in frame 33 and biased downwardly by a spring 68. The purpose of the

roller

63 and 66 is to strip the leaf 30 from the die 29 and to hold the leaf away from contact with the die 29 as the leaf is pulled through the machine and to permit the die 29 to contact the leaf only during the actual stamping operation.

As the leaf '30 leaves the roller 66, it passes over the upper surface of a knurled feed roller 69 (shown in FIG. 4) and then between the roller 69 and a spring biased roller 70, which may be of a suitable yielding material such as rubber. The roller 70 is biased toward the roller 69 by means of a leaf spring 71 carried by a bar 72 mounted transversely across the frame 33. The bias leaf 71 is urged against a U-shaped member 73 having bifurcated end arms 7311 which bear against the ends of the shaft 70a of the roller 70. A cam 74 is rotatably mounted in bar 72 by means of a shaft 74a, the outer end of which passes through an opening in the leaf spring 71 and is secured to the U-shaped member 73. The cam 74 bears against the outer end of a bearing pin 76 set into the bar 72. The cam 74 may be manually rotated by an arm 75 (see FIG. 1). When the cam is in the position with its high point adjacent the pin 76, the shaft 74a pulls the member 73 away from the shaft 70a thus relieving the roller 70 from the bias of the spring 71. When the cam 74 is rotated so that its low point is adjacent the pin 76, the spring 71 pushes the member 73 against the ends of shaft 70a and thus pushes the roller 70 towards the roller 69 so that the foil 30 is held firmly between the two

rollers

69 and 70 and as roller 69 is turned it pulls the foil through the machine. Suflicient play is provided between the shaft 70a and the frame 33 to permit such biasing action.

The bar 72 is extended below the frame 33 to provide a rounded guiding edge 77 over which the leaf 30 passes to a take-up roll 78 journalled in the frame 33.

The feed roller 69 is driven by a gearing mechanism shown most clearly in FLIG. 5. One end of the shaft 79 of the roller 69 is journalled in and passes through a wall of the frame 33 into a gear box 80. The shaft 79 carries two

gears

81 and 82 mounted on the shaft by means of

oneway clutches

83 and 84 of any well-known type. A drive rack 85 engages the top of gear 81 and a drive rack 86 engages the lower side of gear 82. The directions of transmission of the clutches are such that as the rack 85 moves in a direction out of the plane of FIG. it drives clutch 83 to rotate the roller 69 to feed the leaf 30 through the machine, and as the rack 86 moves back into the plane of FIG. 5 it drives clutch 84 to continue the rotation of the roller 69 to feed the leaf 30 through the machine. The

racks

85 and 86 are reciprocated in unison by a pneumatic drive cylinder 87 mounted on the back of frame 33 between the

side plates

2 and 3. Due to the unidirectional gearing arrangement, the length of the drive cylinder 87 need only be one-half of the length of cylinders of this kind which have been required in prior machines of this nature.

The amount by which the leaf 30 is pulled through the machine between each stamping stroke may be adjusted by the position of an adjustable stop 88 which is adapted to be contacted by a bar 89 mounted on the ends of

racks

85 and 86 as they emerge from gear box 80. The stop 88 activates a pneumatic control valve 89 which is mounted by a conduit 90 to any well-known type of pneumatic control which reverses the direction of actuation of the cylinder 87. Therefore, the cylinder '87 moves the

racks

85 and 86 in one direction until bar 89 activates valve 89 and then it reverses its direction to reverse the direction of motion of the racks, but not of the roller 69. The position of the valve 89 carrying the stop 88 may be adjusted by a screw 91 threaded through a block 92 mounted on the frame 33. The screw 90 carries a knurled head 93 so that it may be turned to its desired position of adjustment.

The take-up roll 78 is driven by a pulley 94 engaged by a belt 95 which in turn is driven by a pulley 96 mounted on the shaft of drive roller 69.

Instead of releasing the tensions of the

springs

54 and 55 by lowering the

levers

60 and 61 in order to move the ram 22 for setting up the work, the machine may be provided with an elongated lever 97 bolted at its rear end to the back of cylinder 44 by means of bolts 98. The forward end of the lever 96 is formed into a handle 99 and extends over the top front of the main frame 1 in a position which is readily accessible to the operation. By grasping the handle 99 and drawing it downward, the associated structure is rotated about the pivot bars 47 and the forward end of wedge 37 pushes the roller 38 and its ram 22 down- 'Ward toward the surface of the work table 10 against the tension of the springs 54. For many purposes such operation is more rapid and more convenient.

It is to be understod that the machine is provided with the proper controls for supplying and regulating compressed air to the cylinders 44 and 87 in proper sequence and for supplying and regulating heating current to a heating element within the stamping head 21. However, since such details of such controls are standard and form no part of this invention, they are not shown or described herein, inasmuch as their nature and arrangement will be apparent to persons skilled in the art of hot leaf stamping machines.

Although this invention has been described in connection with a hot leaf stamping machine, it is to be understood that the principles of this invention may be applied to any kind of stamping or pressing machine in which it would be desirable to have the pressure on the work independent of the position of the working head and to have the stamping or pressing mechanism free of transverse pressure during the power portion of the stroke. Other applications of the principles of this invention and of variations in its details will be apparent to those skilled in the art to which it pertains. Therefore, the scope of the invention is defined as set forth in the annexed claims.

What is claimed is:

1. A stamping machine comprising:

a stamping head adapted to exert stamping pressure upon a work piece;

a ram carrying said head and mounted to reciprocate along a first linear path within a supporting structure;

a wedge member provided with surfaces adapted to be forced between a reaction member, carried by said structure, and an end of said ram opposite said stamping head;

power means for driving said wedge along a second linear path disposed at a substantially fixed, relatively small angle with respect to a perpendicular to said first linear path; said wedge member being inflexibly attached to said power means in relation to said second linear path;

the surface of said wedge member, which contacts said reaction member during the final portion of the stamping stroke, comprising a plane;

the surface of said wedge member, which contacts said ram during said final'portion of the stamping stroke, comprising a plane disposed substantially perpendicular to said first linear path.

2. A stamping machine according to claim 1 in which the surface of said wedge member, which contacts the ram during the initial portion of the stamping stroke, comprises a plane disposed at a substantially greater angle with resplect to said perpendicular than said relatively small ang e.

3. A stamping machine according to claim 1 in which the power means comprises a pneumatic cylinder having an internal piston inflexibly connected to said wedge member.

4. A stamping machine according to claim 3 in which said power means is supported in said supporting structure solely by being pivoted to said supporting structure about a pivot axis which is transverse to the direction of travel of said piston, in which there is provided a work table adapted to support the work, and in which said stamping head is biased away from said work table and a manu ally operable lever is secured to said cylinder at a point removed from said pivot axis, whereby the stamping head may be moved manually toward and away from said work table.

5. A stamping machine according to claim 1 in which said reaction member is inflexibly attached to said supporting structure.

6. A hot leaf stamping machine which includes:

a stamping head adapted to exert stamping pressure upon a work piece and adapted to carry a heated stamping die;

a strip of stamping leaf adapted to be supported between said die and said work piece;

means for advancing said strip through said machine comprising a pair of cooperating feed rollers;

and means for driving one of said rollers comprising a pneumatic cylinder connected to a pair of rack members engaging opposite sides of a pair of gears respectively, said cylinder being adapted to drive said racks in a linear reciprocating motion, said gears being mounted through one-way clutches to a driving shaft on said one of said feed rollers, said clutches being oriented to cause said latter feed roller to be driven in the same direction for both directions of travel of said racks.

References Cited UNITED STATES PATENTS BENJAMIN A. BORCHELT, Primary Examiner 15 J. J. DEVITT, Assistant Examiner U.S. Cl. X.R.