US2916990A - Ink pad tensioner for stencil duplicators - Google Patents

Description

Dec. 15, 1959 E. H. DU Bols 2,916,990

INK PAD TENSIONER FOR STENCIL DUPLICATORS Filed Sept. 11, 1957 3 Sheets-Sheet 1 Dec- 15. 1959 E. H. DU Bols 2,916,990

INK PAD TENSIONER FOR STENCIL DUPLICATORS Filed Sept( l1, 1957 3 Sheets-Sheet 2 'l Il IN VEN TOR.

in m De@ 15, 1959 E. H. DU Bols 2,916,990

INK PAD TENSIONER FOR STENCIL DUPLICATORS Filed Sept. 11. 1957 5 Sheets-Sheet 3 United tates iiatent mit ran rizNsioNnR For: sTENCiL nUPLicArons Chicago, Ill., assigner to A. B. ick

Edgar H. Du Bois,

iii., a corporation of Iilinois This invention relates to duplicators or other printing machines and pertains particularly to stencil duplicators in which a stencil is wrapped around an ink pad which is held under tension on a printing drum or cylinder.

One object of the present invention is to provide a new and improved mechanism for holding an ink pad under tension on the printing drum of a stencil duplicator.

Another object is to provide a new and improved ink pad tensioning mechanism which is easy to operate so that the operator may readily remove and replace the ink ad. p A further object is to provide an ink pad tensioning mechanism which is arranged to distribute the tension evenly on the ink pad along its width.

Another object is to provide a new and improved ink pad tensioning mechanism which is easy to manufacture and low in cost.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

Fig. 1 is an end view of a printing drum or cylinder for a stencil type duplicator, equipped with an ink pad tensioning mechanism to be described as an illustrative embodiment of the present invention.

Fig. 2 is a fragmentary elevational view of the tensioning mechanism, taken generally as indicated by a line 2-2 in Fig. l, the mechanism being shown in its rest position, occupied when there is no ink pad on the drum.

Fig. 3 is a view somewhat similar to Fig. 2, but on a larger scale and with the mechanism in its normal operating position, with an ink pad being held under tension by the mechanism.

Fig. 4 is a fragmentary enlarged section View taken generally along a line 4 4 in Fig. 3.

Fig. 5 is a View somewhat similar to Fig. 3, but with the mechanism in its ink pad releasing position.

Fig. 6 is a fragmentary end view showing the tensioning mechanism with parts of the cylinder broken away.

Fig. 7 is a fragmentary enlarged sectional view, taken generally along a line 7--7 in Fig. 2.

It will be seen that the drawings illustrate an ink drum or cylinder 10 for a stencil type duplicator. It will be recognized that cylinder 10 is of the closed type forming a tank or reservoir adapted to hold a supply of ink. A large part of the peripheral surface of cylinder 10 is formed by a cylindrieally curved, perforated diaphragm 12. An ink pad 14 may be wrapped around the perfo rated diaphragm 12 and may be tensioned on the cylinder 10 by means to be described in detail shortly. A printing master in the form of a stencil (not shown) may be wrapped around the cylinder 10 over the ink pad 14. It will be understood that the ink passes from the inside of the drum lil through the perforated diaphragm 12 and wets the ink pad, so that the ink pad becomes saturated with ink. The ink from the ink pad passes through the openings in the stencil and is transferred to copy sheets which are pressed against the drum 10 in the course of the printing operation.

Patented Dec. 15, 1959 ice The present invention is concerned with the manner in which the ink pad 14 is held under tension on the printing drum 10. At its head end, the ink pad 14 is simply anchored by being hooked over a plurality of studs, or hooks 16, which are securely mounted on the drum 10. Thus, the studs 16 are immovable with respect to drum 10. An apertured bar 18 is secured to the head end of the ink pad 14- and is adapted to be hooked over the studs 16. The studs are mounted on a wall 20 which is receded in position with respect to the extended circle of the diaphra-gm 12 so that the studs will not come into contact with the copy sheets or other parts of the duplieating machine.

The tail end of the stencil 14 is also tted with a reinforcing bar 22, made of sheet metal or other suitable material. A plurality of apertures 24 are formed in the bar 22 and are distributed along the width of the ink pad 14. The tail end of the ink pad 14 is adapted to be held on the drum 10 by a mechanism 26 which is adapted to tension the ink pad.

The tensioning mechanism 26 comprises an elongated hook plate or member 28 formed with a plurality of hooks 30 adapted to be received in the openings 24 provided in the bar 22. The hook plate 23 is arranged to extend longitudinally of the printing drum 10 and is disposed in a receded position with respect to the extended circle of the diaphragm 12. The hooks 3i) are aligned with each other along a line extending longitudinally of the printing drum 10 and are spaced longitudinally along the length of the drum, with a spacing corresponding to that of the openings 24.

The hook plate 28 is guided for sliding movement in a generaliy peripheral direction with respect to the printing drum 10. In this case, the hook plate 28 is formed with a pair of elongated slots 32 which extend in a generally peripheral direction and are parallel to each other. The plate 28 is supported over and is slidable along a supporting wall 34 which recedes from the periphery of the diaphragm 12. Guide pins 36 are mounted on the wall 34 and are arranged to extend outwardly through the slots 32. The t between the pins 36 and the slots 32 may be fairly loose so that the hook plate 28 will be freely movable.

The hook plate 28 is adapted to be moved by means of an elongated operating plate or member 38. As shown, a portion of the operating plate 38 overlies a portion of the hook plate 28. The operating plate 38 extends lengthwise of the cylinder and is guided for lengthwise sliding movement. Thus, the illustrated operating plate 38 has a .pair of elongated slots 40 and 42 which extend lengthwise of the cylinder 10. The guide pins 36 extend outwardly through the longitudinal slots 40. Washers 44 and clips 46 may be mounted on the pins 36 to retain the operating plate 38 thereon. The t between the pins 36 and the slots 4l) and 42 is sufficiently loose to permit free movement.

In order that the hook plate 28 may be moved peripherally in response to the longitudinal movement of the operating plate 38, a cam 48 is arranged to act between the plates 28 and 38. In this case, the cam 48 takes the form of an elongated diagonal slot in the operating plate 3.8. The slot 48 is adapted to be followed by a roller or pm 50 which is mounted on the hook plate 28 and extends` outwardly into the slot 48. When the operating plate 38 1s moved longitudinally, the diagonal cam slot 38 induces peripheral movement of the hook plate 2S.

By means of a spring 52, the operating plate 38 is normally urged in one longitudinal direction so as to bias the hook plate 28 in a direction such as to tension the ink pad 14. Thus, the spring 52 tends to move the operating plate 38 to the left, as shown in Fig. 3, and thereby tends to draw the hook plate 28 upwardly. In

this case, the spring 52 is of the coil spring type and is tensioned between a pin 54 or the like on the operating plate 38 and a pin or other anchor 56 on the cylinder wall 34. lt will be observed that the spring 52 extends longitudinally of the cylinder between the operating plate 38 and the cylinder wall 34.

At its upper edge, the operating plate 38, as shown in Figs. 3 and 4, is fonned with a generally L-shaped flange 58 which spaces the upper portion of plate 38 from the cylinder wall 34, so as to provide room for the spring 52. The extreme edge of the flange 58 is retained and guided under an enlarged head 60 which is formed on a stud 62 mounted on the cylinder wall 34. in this way, the upper edge of the operating plate 38 is kept from swinging away from the cylinder wall 34. The tit between the flange 58 and the stud 62 is quite loose so Vas to provide for free and easy movement of the operating plate 38. At its right-hand end, the operating plate 38 is formed with an upstanding lange 64 which serves as a handle or manually moving the operating plate 38.

When the operating plate 38 is moved to the right, as shown in Figs. 3 and 5, the hook bar 28 is moved in a direction to relax the tension in the ink pad 24 and eventually release the ink pad.

1n Fig. 5, the tensioning mechanism 26 is shown in its pad-releasing position with the operating plate 38 moved fully to lthe right. In order to detain the mechanism in this position, while the ink pad is being removed or replaced, the slot 42 is formed with a detent notch 66 at its left-hand end. The notch 66 extends in a peripheral direction and downwardly as seen in Figs. 3 and 5. When the operating plate 38 is fully moved to the right, as seen in Fig. 5, the right-hand end of the plate may be swung upwardly to engage the notch 66 with the righthand guide pin 36. The engagement between the notch 66 and the guide pin 36 will retain the operating plate 38 in the pad-releasing position until the operator swings the right-hand end of the operating plate downwardly. It will be understood that the it between the headed stud 62 and the upper edge of the operating plate 38 is sufciently loose to permit the slight upward swinging movement which is involved in engaging the notch 66 with the pin 36. in the course of such swinging movement, the operating plate 38 pivots about the left-hand guide pin 36.

Fig. 2 illustrates the pad-tensioning mechanism 36 in its rest position occupied when there is no ink pad on the printing drum 10. In this position, the operating plate 38 is moved fully to the left by the spring 52, and the hook plate 28 is moved fully in an upward direction.

When the ink pad is to be installed on the drum 10, the head end of the ink pad is hooked over the studs 16 and the pad is wrapped around the diaphragm 12. The operating plate 38 is then fully moved to the right, to move the hook plate 28 fully in a downward direction, as shown in Fig. 5. The operating plate is swung upwardly so as to engage the notch 66 with the right-hand pin 36. This detains the operating plate in its padreleasing position. The apertured bar 22 at the head end of the ink pad 14 may then be mounted on the hooks 30.

Tension is applied to the pad 14 by swinging the operating plate 38 downwardly to release the notch 66 from the pin 36. The operating plate 38 is then allowed to return to the left under the force of the spring 52. The hook plate 28 is drawn upwardly until the ink pad 14 is drawn tight around the diaphragm 12. The spring 52 maintains tension on the ink pad 14 at all times. Fig.

3 shows the tensioning mechanism 26 in its normal operating position with the pad 14 held under tension.

It will be seen that the diagonal cam slot 48 supplies the tensioning force to the hook plate 28 through the medium of the roller 50. The hook plate 28 is free to pivot sufhciently about the roller 50 to equalize the tension on the various hooks 34). Thus, the engagement between the guide slots 32 and the pins 36 prevents any substantial movement of the hook plate 28 in a lengthwise'direction with respect to the cylinder 10 but the t between the slots and the pins is suiciently loose to permit the hook plate 28 to rock or pivot about the axis of the roller 50. Such freedom for pivoting movement assures that the tension in the ink pad 14 will be evenly distributed along the width of the pad.

It will be recognized that the tensioning mechanism is extremely easy to operate yet is highly eiTective in tensioning the pad. Moreover, the tensioning mechanism is easy to manufacture and low in cost.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention as exemplified in the foregoing description and defined in the following claim.

I claim:

In a stencil type duplicator, the combination comprising a printing cylinder for receiving an ink pad and a stencil, means for anchoring one end ot the ink pad to the cylinder, a hook plate for securing the opposite end of the ink pad to the cylinder, said hook plate having a plurality of hooks thereon spaced along the length of the cylinder for connection of the ink pad to said plate, said hook plate being disposed on said cylinder along the length thereof, a plurality of parallel slots in said plate, said slots being elongated and arranged to extend in a generally peripheral direction with respect to said cylinder, a plurality of guide pins secured to said cylinder and extending outwardly through said slots to guide said plate for generally peripheral movement on said cylinder, an elongated operating plate extending longitudinally of said cylinder over said hook plate, said operating plate having a plurality of elongated slots therein extending lengthwise of said cylinder and received over said guide pins to guide said operating plate for movement longitudinally of said cylinder, said operating plate having an elongated generally diagonal cam slot therein, a follower roller mounted on said hook plate and extending into f said cam slot for moving said hook plate peripherally in response to longitudinal movement of said operating plate, a spring urging said operating plate in one longitudinal direction to bias said hook plate in a peripheral direction such as to tension the ink pad, said operating plate being movable in the opposite direction against the-force of the spring to release the ink pad, and a notch formed adjacent to one end of one of said guide slots in said operating plate for receiving the corresponding guide pin to detain said operating plate in its pad-releasing position.

References Cited in the tile of this patent UNITED STATES PATENTS 1,662,284 Shea Mar. 13, 1928 2,579,517 Rowell et al Dec. 25, 1951 2,645,177 Dressel et al July 14, 1953 FOREIGN PATENTS 817,308 Germany Oct. 18, 1951

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