US2108850A - Marking machine - Google Patents

Description

Feb. 22, 1938. 0. w. FROMM MARKING MACHINE Filed Dec. 19, 1934 3 Sheets-Sheet l l l I I I I A l I l I I lllllllllll 1 wig 531% Feb. 22, 1938. t o w. FROMM I 2,108,850

Q MARKING MACHINE I F'iLed Dec. 19, 1934 s Sheets-Sheet 2 Patented Feb. 22, 1938 amass PATENT OFFIQE MARKING MACHINE Otto Willy Fromm, Frankfort-on-the-Main, Germany, assignor to United Shoe Machinery Corporation, Paterson, N. J., a corporation of New Jersey Application December 19, 1934, Serial No. 758,160

28 Claims.

This invention relates to pressing machines and is illustrated herein as embodied in a machine particularly adapted for use in impressing characters or other marks on the soles of boots and shoes.

Machines of the type disclosed in United States Letters Patent No. 1,028,567, granted June 4, 1912 on an application filed in the names of William Gordon and Laurence E. Topham, are being extensively used to make impressions on the soles of boots and shoes. Machines of this type include, in connection with a marking die adapted to be moved in a stroke of predetermined length regardless of the thickness of the work to be operated upon, a work support which is arranged to yield in response to a predetermined limited pressure of the work against it. Although provision has thus been made for insuring uniformity in the pressure to be applied in marking work-pieces of different thicknesses, the time during which .the marking head is in engagement with the work may vary, depending upon the thickness of the work. However, the depth of the impression of the die, which it is desired to maintain uniform, is affected not only by the pressure of the die but also by the length of time during which the pressure is applied, and hence it is necessary when operating upon soles varying substantially in thickness to adjust the work support manually to compensate for varying thicknesses of work in order that the dwell of the marking die on the work as well as the amount of pressure may be uniform. This operation of adjusting the work support is time-consuming and its success depends to a large extent upon the skill and experience of the operator.

It is an object of the present invention to provide an improved machine which will overcome the above-mentioned difiiculties. To this end the machine is provided with an operating head arranged to be moved manually toward a work piece on a fixed work support to measure the thickness of the work and then to be moved by power means which is inhibited when a predetermined limited pressure of the head against the work has been set up. The operating head, illustrated herein as a marking head, is moved at the beginning of a marking operation against the work-piece by a lever mounted and arranged to be actuated by the operator. After this measuring movement of the marking head has been completed, it is caused to apply a predetermined limited pressure to the work by power means, the operation of which is inhibited, as stated above, by connections constituting an important feature of the invention and which are arranged to yield in response to any pressure in excess of the predetermined limited pressure referred to above. Thus, in the operation of the illustrated machine, the marking head is caused to apply a predetermined pressure to each work-piece from substantially the beginning to the end of the unvarying stroke of the power means regardless of the thickness of the work-piece. Although the present invention is illustrated as embodied in a marking machine, it is evident that the invention is not limited in its utility to use in such machines but may be used in other types of machines where it is necessary or desirable to apply pressure to a work piece.

With the above and other objects and features of the invention in view, the invention will now be described in connection with the accompanying drawings and pointed out in the appended claims.

In the drawings,

Fig. 1 is a View in side elevation, partly in section, of a machine embodying the present invention;

Fig. 2 is a view on an enlarged scale, partly in section, of the head of the machine showing the position of the parts when the machine is at rest; and Fig. 3 is a view similar to Fig.2 but showing the position of the parts during movement of the head toward the work.

The illustrated machine is provided with a frame I0 having a forwardly extending bracket l2 to which is rigidly secured a work supporting horn M as shown in Fig. 1. The horn I4 is secured to the bracket I2 in such a position that thework engaging surface I6 of the horn I4 is directly underneath an operating head [8 slidably mounted in the upper portion of the frame I E! and which, as herein illustrated, is provided with a plurality of marking dies. A treadle 2!! is fulcrumed at 22 to the lower portion of the machine frame l0 and an upwardly extending rod 24 is pivotally secured to the treadle 20 by a pin 26. A lever 28 pivoted at its right-hand end (Fig. 1) to the machine frame II] by the stud 3|] is provided with a slot through which the upper end of the rod 24 passes. The rod 24 is provided with a fixed collar 32 which engages the lower edge of the lever 28. The upper end of the treadle rod 24 is provided with a pair of adjusting nuts 34 between which and the lever 28 is interposed a coiled spring 36. When the nuts 34 are properly adjusted the spring 36 holds the collar 32 against the lower edge of the iii lever 28 and the spring 36 thus forms a yieldable connection between the treadle rod 24 and the lever 28. The lever 28 is provided at its lefthand end with an elongated slot 38 through! which passes a pin 46 driven into a hole formed in a bracket 4I on which the head I8 is rotatably mounted so as to permit any of the marking dies to cooperate with the horn I4 to make an impression on a work-piece disposed therebetween. When the treadle 20 is depressed the spring 36,: bearing against the upper edge of the lever 28, will cause the lever 28 to move in a counterclockwise direction carrying the marking head 56 downwardly against a work piece on the support I4. After the marking head I8 has engaged the work, continued downward movement of the treadle 20 will further compress the spring 36 and will cause a collar 42 secured to the trea-' dle rod 24 to engage a clutch tripping mecha-' nism which will now be described.

The collar 42 just above referred to is adjustably secured to the treadle rod 24 and is so arranged that after the marking headi I8 engages the work it strikes one end of a lever 44 fulcrumed at 46 to the machine frame Ill. *The other end of the lever 44 has pivotally secured thereto a link 46 which is provided at its upper end with a notch 56 engaging an abutment plate 52 secured to one arm of a bell crank lever 54. When the lever 44 is swung in a counterclockwise direction by engagement with the collar 42 on the downwardly moving treadle rod 24, the end of the arm 56 of the bell crank lever 54 is moved out of engagement with a shoulder 58 formed on the sleeve or cage 66 of a Horton clutch mounted on a drive shaft 62. This turning of the bell crank lever 54 releases the clutch so that rotation of the shaft 62 begins. The machine is provided with a pulley 63 which may be driven from any suitable source of power. The clutch tripping mechanism above described is so arranged that the machine performs only one cycle of operation, even though the operator fails to release the treadle after the clutch has been tripped. To this end the lever 54 is normally urged in a clockwise direction by a spring 64 which is secured at one end to the lever 44 and at its other end to the bell crank lever 54. The link 48 is normally held against the abutment 52 by a spring 66. When the machine has been put into operation the radially extending Wall of the shoulder 58 strikes an arm I6 formed as a part of a link 48, which is moved out of engagement with the abutment 52 on the bell crank lever 54. At the same time, the bell crank lever 54 isrotated in a clockwise direction by a spring I2, thus moving the abutment 52 to a position where it cannot engage the notch 56 in the link 48 until after the treadle 26 has been released by the operator. The end of the arm 56 of the bell crank lever 54 is their free to follow the contour of the cam 66, and when the shoulder 58 again engages the end of the arm 56 the machine comes torest and cannot I perform another cycle of operation until the treadle 26 has been released by the operator and again depressed.

, The marking head I8, as previously stated, is rotatably mounted in the bracket 4|. If it is necessary or desirable to apply heat to facilitate the marking operation, the head I8 may be heated by any suitable means. The bracket 4! is se cured by studs 14 to the lower end of a cylinder i6 (Figs. 2 and- 3) which is slidably mounted in a long bearing formed in a forwardly extending bracket TI secured to the, machine frame I0. The

'a lock nut I28.

lower end of the cylinder 16 is closed and a hollow plunger '38 is arranged to be reciprocated in the cylinder which forms an extensible connection between the marking head I8 and the power means for operating the head. The hollow plunger I3 and the cylinder cooperate to form a liquid-containing chamber which is filled with oil or other suitable fluid constituting one element of a hydraulic connection between the plunger and cylinder. The plunger 76 fits closely in the cylinder I6 to prevent the oil contained in the cylinder from escaping between thewalls oi the cylinder 16 and the plunger I6. The lower portion of the plunger I8 is provided with an inwardly extending annular ring 86 which forms a seat for a relief valve 82. A coiled spring 84 holds the valve against the seat, tension being placed on the spring by adjusting means now to be described. The upper end of the coiled spring 84 bears against a washer 86 which in turn engages the lower race of a ball bearing 66 the upper race of which is engaged by the lower end of a threaded sleeve 96 which is threaded in the inside upper portion of the plunger I8. The upper portion of the sleeve 96 is provided with a plurality of gear teeth 92 meshing with a worm 94 mounted on a shaft 96. The shaft 66 is journaled in bearings formed in a cap 98 which is screwed to the top of the plunger 18. The shaft 96 may be provided with a crank or hand wheel SI (Fig. 1) to facilitate turning the shaft 96. By turning the shaft 96 tension on the spring 84 may be increased or decreased. It is apparent that if V the tension on the spring 64 is increased a greater pressure will be required to open the relief valve 82 and, conversely, if less tension is placed on the spring 84 less pressure will be necessary to open the valve 82.

As shown in Figs. 2 and 3, the valve 82 is provided with an opening into which fits a ballshaped valve I62 which is provided with a rod I64 extending upwardly through the top of the plunger 16. A spring I66 interposed between the cap 93 and an adjusting nut I68 tends to move the valve I02 upwardly to close the opening in the valve 82. The upper end of the rod I64 is arranged to engage the lower end of a screw abutment I I6 whereby the valve I62 is held away from the valve 82 when the plunger i8 is in its initial position, thus permitting relative movement between the plunger and the cylinder which occurs when the marking head is moved into engagement with the work-piece and after the marking operation has been completed. The screw abutment H6 is threaded into a bracket H4 secured to the upper portion of the bracket 17. The screw I I6 is maintained in adjusted position by a lock nut I I5. The screw I I6 is so adjusted that the end of the rod E64 will strike the screw just before the plunger 78 returns to its initial position at the end of a cycle of operations. 7

The connections between the drive shaft '62 and the plunger '18 will now be described. An eccentric IIB (Fig.1) is secured to the shaft 62 and is surrounded by an eccentric strap I 58. A rod I26 is threaded into a boss I22 formed as a part of the strap '1 i8 and is locked to the boss I22 by. a look nut' B24. The upper end of the rod I26 is threaded into a yoke I26 and held in position by The yoke I26 is connected to a lever I36 by a pin I32. The lever I36 is forked at its forward end to receive an upwardly extending portion 634 of the bracket 'i'i which is provided with a holeto receive a heavy pin I36 forming a fulcrum for the lever I30. A heavy spring I38 (Fig. 1) secured at one end to the lever I30 and at its other end to the cap 98 forms a connection between the lever I39 and the reciprocating plunger I8. As shownin Figs. 2 and 3, the lever I3!) is cut away at its lower edge to receive a bearing block M9, the lower surface of which is curved to provide for rolling contact between it and the top of the cap 93. Marking pressure is transmitted to the head I8 from the power mechanism through the connections described just above.

Although the parts of the machine have been described in detail it will be well at this point, for a better understanding of the invention, to describe briefly the operation of the machine. After the desired marking character on the head I8 has been brought into marking position a shoe or other work piece is placed on the worksupport I4 by the operator. The treadle 20 is then depressed and the marking head brought into engagement with the work. The spring 36 surrounding the treadle rod 24 then yields and downward movement of the rod 24 continues. During this preliminary or measuring movement of the head I8 the hollow plunger I8 remains in the position shown in Figs. 1 and 2. The valve I82 in the lower end of the plunger I8 is held open and oil or other fluid contained therein, which forms the hydraulic connection between the cylinder 76 and the plunger 78, is free to flow into the cylinder 16 with the result that when the measuring movement of the head is completed the chamber in the portions of the cylinder 16 and plunger 18 below the valve 82 is filled with fluid.

After the measuring movement of the head I8 has been completed the clutch of the machine is tripped by the engagement of the collar 42 on the downwardly moving treadle rod 24 with the clutch tripping lever 44. The plunger 18 is then moved downwardly by power. At the beginning of the downward movement of the plunger 18 the valve N32 is closed and further flow of fluid through it from the plunger I8 into the cylinder 76 is prevented. After the valve I02 is closed the plunger I8 and the cylinder I6 move downwardly as a unit for a short distance. The extent of this movement depends largely upon the character and thickness of the work. For example, if the work piece is relatively thick and soft the movement of the plunger I8 and the cylinder I5 as a unit will be longer than when the work is thin and hard. In other words, the downward movement of the plunger I8 andthe cylinder I6 as a unit continues until a predetermined pressure has been applied to the work. When the pressure applied to the work becomes greater than that for which the spring 84 has been set, the spring 84 will yield and the valve 82 will open, thereby permitting the flow of fluid from the cylinder It; into the hollow plunger I8. Thus, while the plunger I8 completes its downward movement throughout the stroke imparted to it by the eccentric I I 6, the valve maintains the fluid pressure for which it was set, and the cylinder 16, to which the head I 8 is secured, remains stationary. During this period, the plunger I8 and cylinder 16 yield relatively to each other, thereby preventing the head I8 from exerting pressure against the work piece in excess of the amount for which the setting of the spring 84 has. been made. After the plunger 18 has completed its downward movement it is returned to its initial position. At the beginning of this return movement the valve 82 closes and the plunger I8 and thecylinder I6 are moved upwardly as a unit until the end of the rod I04 engages the abutment screw I I0 and opens the valve I02. A spring I 44, secured at one end to the machine frame I0 and at its other end to a hook I46 on the lever 28, then moves the cylinder I6 and the head I8 attached thereto to their initial position, as shown in Figs. 1 and 2. The treadle 2!] of the machine is ordinarily released shortly after the plunger I8 begins its movement but even if the treadle 2B is not released until after the cycle of operation of the machine has been completed, the clutch will not be tripped again until after the treadle has been returned to its original position. When the treadle is returned to its original position a collar I48 on the treadle rod 24 engages the lever 44 and returns it to the position shown in Fig. 1. The parts of the machine are now in position to begin another cycle of operations.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a machine for operating upon shoes, a work support, an operating head mounted for movement toward and away from said support, manually operated means for moving the head into engagement with a work piece on said support to measure the thickness of the work, and poweroperated means for causing the headto press against the work, said means including members constructed and arranged to yield relatively to each other when a predetermined pressure of the head against the work has been set up.

2. In a machine for operating upon shoes, a work support, an operating head mounted for movement toward and away from said support, operator-controlled means for moving the head into engagement with a work piece on said support, and power-operated means for pressing the head against the work, said means including one member driven through a definite stroke and another member operatively associated with and arranged to be displaced relatively to said firstmentioned member in response to pressure in excess of a predetermined amount.

3. In a marking machine, a work support, a marking head movable toward said support to press a work piece thereon, operating means for said head, means connecting said head and operating means comprising relatively displaceable members cooperating to form a fluid chamber, and means mounted on one of said members operable in response to a predetermined pressure of said head against the work piece to open said chamber.

4. In a marking machine, a. work support, a marking head mounted for movement toward said support, operating means for said head for causing the latter to press against a work piece on said support, and means for controlling the pressure applied to said head comprising connections between said head and operating means constructed and arranged to yield when a predetermined pressure of said head against the work piece has been set up.

5. In a marking machine, a work support, a marking head, members mounted for movement toward and away from said support, one of said members carrying said head, means associated with the other of said members for locking said members against vmovement relatively to each other in one direction, and power-operated means constructed and arranged to cause said marking head toapply pressure to a work piece on said support, said locking means being constructed and arranged to permit relative movement between said members when a predetermined pressure of said head against the work piece has been set up.

6. In a marking machine, a work support, in terconnected members mounted to move relatively to each other toward and away from said support, a marking head mounted on one of said members, manually operated means connected to the last-mentioned member for moving said head against a work piece on said support, power operated means connected to the other of said members and constructed and arranged to apply pressure to said other member after the manually operated movement of the marking head has been completed, and means for preventing said pweroperated means from applying pressure to said other member in excess of a predetermined amount.

7. In a marking machine, a work support, a movable marking head, power operated. means for moving the marking head toward and against a work piece on said support, a manually extensible connection between the marking head and the power operated means, means for locking said connection prior to the operation of the power means, and means constructed and arranged to permit said connection to yield after a predetermined pressure has been applied to a work piece.

8. In a marking machine, a work support, a movable marking head, power operated means for moving the marking head against a work piece on said support to apply a mark to the work, an extensible connection between the marking head and the power operated'means, manual means for extending said connection to move the marking head into engagement with the work, means for locking said connection after the manual movement of the head has been completed, and means constructed and arranged to permit said connection't'o yield after a predetermined marking pressure has been applied to the work by the power operated means.

9. In a marking machine, a work support, a movable marking head, power operated means for moving the marking head against a work piece on said support to apply a mark thereto,

an extensible connection between the marking head and the power operated means, manually operated means for extending said connection to move the marking head into engagement with the work, means for locking said connection after the manual movement of the head has been completed, and pressure relief mechanism constructed and arranged to permit said connection to yield after a predetermined marking pressure has been applied to the work by the power operated means.

10. In a machine for operating upon shoe parts, a work support, an operating head, power means for operating said head toward and away from said work support, an extensible connection between said head and power means, one member of said connection being operated through a definite stroke by said power means, another member of said connection being mounted for movement relatively to the first-meme tioned member to permit a preliminary measuring movement of said head, and means connecting said members for maintaining a constant pressure therebetween throughout the stroke of the power means after a predetermined pressure of the head against the work-piece on said support has been set up.

11. In a pressing machine, a work support, an operating head, power means for operating said head toward and away from said support, extensible connections between said head and power means cooperatingwith each other to form a liquid-containing chamber, and means for controlling the flow of. liquid into and out of said chamber comprising a; valve constructed and arranged normally to close said chamber but operable in response to a predetermined pressure of the head against the work-piece to permit the flow of liquid out of the chamber.

12. In a marking machine, a work support, a marking head movable toward said support, manually operated means yieldably connected to said head for moving said head toward said support, power operated means connected to said head for applying pressure to a work piece on said support, and hydraulic connections between saidhead and said power operated means constructed and arranged to yield when a predetermined pressure has been. applied to said work piece. a

13. In'a marking machine, a rigidly mounted work support, manually operated means yieldingly connected to said head for moving said head toward the work support, power operated means for applying pressure to a work piece on said support, means secured to said manually operated means for rendering the power operated'means effective to move the head after the head has been brought. into engagement with the work, and hydraulic connections between said head and said power operated means constructed and arranged to yield when a predetermined pressure has been applied to said work piece. a

14. In a, marking machine a work support, a marking head, a lever connected to the markin head for actuation by the operator, a cylinder secured to the marking head, a hollow plunger operating in the cylinder, power mechanism, connections to the power'mechanism for moving the plunger, and a valve for controlling the flow of liquid between the cylihderand plunger constructed'and arranged to open when a predetermined pressure has been set up between the marking head and the support.

15. In a marking machine, a work support, a marking head, a lever connected to the marking head constructed and arranged to be actuated by the operator to move the marking head toward the support for measuring the thickness of the work, a cylinder secured to the marking head, a hollow plunger operating in said cylinder, power mechanism, connections between the plunger and the power, mechanism for moving the plunger, and means arranged to permit the flow of liquid between said cylinder and said plunger when a predetermined pressure has been set up between the marking head and the support.

16. In a marking ma'chine, a work support, a marking head, a lever connected to the marking head constructed and arranged to be actuated by the operator to move the marking head toward the work to measure the thickness of the work,

plunger is being operated by the power mechanism.

17. In a machine for operating upon shoes, a work support, an operating head, manually operated means for moving the head toward the support to measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve in said plunger arranged to permit flow of fluid between the plunger and cylinder during measuring movement of the head and arranged to be closed during reciprocating movement of the plunger, and a second valve arranged to prevent flow of fluid between the cylinder and the plunger during reciprocating movement of the plunger until a predetermined pressure has been applied to the Work.

18. In a machine for operating upon shoes, a work support, an operating head, manually operated means for moving the head toward the support to measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve arranged to prevent flow of fluid between the cylinder and the plunger during reciprocating movement of the plunger until a predetermined pressure has been applied to the work, and a valve seated in said first-mentioned valve and constructed and arranged to permit flow of fluid between the plunger and the cylinder during measuring movement of the head and arranged to be closed during reciprocating movement of the plunger.

19. In a machine for operating upon shoes, a work support, an operating head, manually operated means for moving the head toward the support to measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve arranged to prevent flow of fluid between the cylinder and the plunger during reciprocating movement of the plunger until a predetermined pressure has been applied to the work, and a second valve arranged to be open to permit flow of fluid between the plunger and the cylinder while the plunger is at rest and arrangedto close during reciprocating movement of the plunger.

20. In a machine for operating upon shoes, a work support, an operating head, manually operated means for moving the head toward the support to measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve arranged to prevent flow of fluid between the cylinder and the plunger during reciprocating movement of the plunger until a predetermined pressure has been applied to the work, a second valve arranged to be open to permit flow of fluid between the plunger and the cylinder while the plunger is at rest and arranged to close during reciprocating movement of the plunger, and means arranged to open said second valve when the plunger returns to its initial position.

21. In a marking machine, a machine frame, a work support rigidly secured to said frame, a marking head arranged for movement toward and away from said support, a lever connected to said head constructed and arranged to be actuated by the operator to move said head toward said support to measure the thickness of a work piece on said support, a cylinder secured to the marking head, a hollow plunger operating in said cylinder, power mechanism, connections between the power mechanism and the plunger for moving the plunger, a valve in said plunger arranged to open to permit relative movement between said plunger and said cylinder when a predetermined pressure has been applied to the work, and a second valve in said plunger arranged to open to permitrelative movement between said plunger and said cylinder during movement of said head away from said support.

22. In a marking machine, a machine frame, a Work support rigidly secured to said frame, a marking head arranged for movement toward and away from said work support, a lever connected to said head constructed and arranged to be actuated by the operator to move said head toward said support to measure the thickness of a work piece on said support, a cylinder secured to the marking head, a hollow plunger operating in the'cylinder, power mechanism, connections between the power mechanism and the plunger for reciprocating the plunger, a valve in said plunger arranged to prevent the flow of fluid be tween the cylinder and the plunger during reciprocation of the plunger until a predetermined away from said work support, a lever connected to said head constructed and arranged to be actuated by the operator to move the head toward the support to measure the thickness of a work piece on the support, a cylinder secured to said head, a hollow plunger operating in said cylinder, power mechanism, connections between the plunger and the power mechanism for reciprocating the plunger, a valve in said plunger constructed and arranged to open to permit relative movement between the plunger and the cylinder during movement of the marking head to inoperative position, and a second valve in said plunger constructed and arranged to open to permit relative movement between the plunger and the cylinder when a predetermined pressure has been applied to the work.

24. In a machine for operating upon shoes, a work support, an operating head, manually operated means for moving the head toward the support to measure the thickness. of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve arranged to prevent flow of fluid between the cylinder and the plunger during reciprocating movement of the plunger until a predetermined pressure has been applied to the work, a second valve having a portion extending through said plunger, and an abutment adjustably secured to the frame of said machine con structed and arranged to engage said second valve to open the Valve when the plunger is returned to its initial position.

25. In a machine for operating upon shoes, a

work support, an operating head, manually operated means for moving the head toward the support to measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections between said plunger and said mechanism for reciprocating the plunger, a valve seated in, the lower portion of said plunger, a sleeve threaded in said plunger, a spring interposed between said valve and said plunger to prevent opening of the valve until a predetermined pressure has been applied to the work, means for adjusting said sleeve to vary the tension of said spring, and a second valve arranged to be opened to permit flow of fluid between the plunger and cylinder while the plunger is at rest and arranged to be closed during reciprocating movement of the plunger.

26. In a machine for operating upon shoes, a work support, an operating head, manually opated means for moving the head toward the support to 'measure the thickness of a work piece on said support, a cylinder secured to the head, a hollow plunger operating in said cylinder, power mechanism, connections'between said plunger and said mechanism for reciprocating the plunger, a valve seated in the lower portion of said plunger, a sleeve threaded in'said plunger, a spring interposed between said valve and said plunger to prevent opening of the valve until a predetermined pressure has been applied to the work, means for adjusting said sleeve to vary the tension of said spring, a second valve having a portion extending through said plunger, and an abutment adjustably secured to the frame of the machine constructed and arranged to engage said second valve to open the valve when the plunger is returned to its initial position.

' 27, In a marking machine, a machine frame, a work support rigidly secured to said frame, a marking head arranged for movement toward and away from said support, a lever connected to said head constructed and arranged to be actuated by the operator to move the head toward said support to measure the thickness of a work piece on said support, means for returning the head to its initial position, a cylinder secured to the marking head, a hollow plunger operating in said cylinder, power mechanism arranged to be rendered effective to move the head afterthe work has. been measured, connections between the power mechanism and the plunger for reciprocating the plunger, a valve in said plunger arranged to open to permit relative movement between said cylinder and said plunger when a predetermined pressure has been applied to the work, and a second valve constructed and arranged to open during return movement of the head to permit the cylinder and plunger to m returned to their initial positions.

28. In a marking machine, a machine frame, a 'WOIk support rigidly secured to said frame, a marking head arranged for movement toward and away from said support, a lever connected to said head constructed and'arranged to be actuated by the operator 'to move the head toward said support to measurerthe thickness of a work piece on said support, means for returning the head to its initial position, a cylinder secured to the marking head, a hollow plunger operating in said cylinder, power mechanism, connections between the power mechanism and the plunger for reciprocating the plunger, means for rendering the power mechanism effective to reciprocate the plunger after the work has been measured, a valve in said plunger arranged to open to per- 'mit relative movement between said cylinder and said plunger when a predetermined pressure has been applied to the work, and a second valve constructed and arranged to open during return movement of the'head'to permit the cylinder and" plunger to be returned to their initial positions."

' O'ITO WILLY FROMM.

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