US2014765A - Cutting mechanism for wrapping machines - Google Patents

Description

Set. ,17, 1935. W. HOPPE WW CUTTING MECHANISM FOR WRAPPIKQG MACHINES Filed May 29, 1934 2 Sheets-Sheet l INVENTOR l/14f; w *M TTORNEYS Sept. 17, 1935. HOPPE 2,@14,765

CUTTING MECHANISM FOR WRAPPING MACHINES Filed May 29, 1954 2 Sheets-Sheet 2 INVENTOR TTORNEYS Patented sept. 17, 1935 UNITED STATES PATENT OFFICE William Hoppe, Springfield, Mass., assignor to National Bread Wrapping Machine 00., Springfield, Mass., a corporation of Massachusetts Application May 29, 1934, Serial No. 728,111 8 Claims. (Cl. 164-43) This invention relates to mechanism for severing wrapper sheets from webs, and is particularly intended for use where the-severed sheets are delivered by a gripper or other means to some further device such as a wrapping machine. In certain aspects the invention is directed to improvements on the cutting mechanism shown in the prior application of Hoppe and. Lyon Serial No. 644,066, filed November 23, 1932. In themechanism shown in that application, cutter control devices were employed which permitted a very rapid cutting speed and yetdecelerated the cutters rapidly and with a substantially harmonic motion so that they were brought to rest without shock. The present invention includes mechanism for accomplishing the same general result, but improves upon the prior device by preventing any danger of the linkage becoming caught on dead center by reason of an accidental overtravel. The present invention also improves upon the prior device by providing a cutting mechanism that will sever and position a web for seizure by a gripper in a constant or determinable position irrespective of the particular nature of the web material. This avoids a difliculty formerly inherent in web cutting and delivering mechanisms, in that while they would work properly on one material, such as paper, they would fail to present the severed end of the web in correct position when a different material, such as the various cellulose derivatives, were used.

Referring to the drawings:

Fig. 1 is a side elevation, partly in section, showing a web cutting mechanism constructed in accordance with the invention;

, Figs. 2 and 3 are details corresponding to Fig. 1 but showing the parts in different positions;

Figs. 4 and 5 are details of the web end positioning device in different conditions of adjustment; and

Fig. 6 is a detail side view of certain of the linkage shown in Fig. 2, looking from line 66 of that figure.

The invention has been shown as applied to the web feed of a wrapping machine of the type shown in the Smith and Hoppe Patents 1,953,195 and 1,953,196, and will for convenience be described specifically in one preferred form. The cutting mechanism is carried on a sub-frame I secured by a shaft II and a bolt I2 to the main frame I3, I4, of the wrapping machine. A web to is led from any suitable supply over a guide roll I to the surface of a constantly rotating snubbing roll I6, and around a floating roll I! mounted for travel in guideways I8. Roll I5 is carried in arms I 9 pivoted at 20 and adjustably connected to the frame at 2I, so that the arc of contact of the web with the snubbing roll may be varied. From the floating roll II the web travels over a guide plate 22 secured to a cross piece 23. A 5 roll 24, preferably having a rubber surface, is mounted on a shaft 25 just beyond the guide plate, and is restrained from backward motion by a spring pawl 26 engaging a ratchet 21. Asecond similar roll 28 is mounted on arms 29 extendl0 ing from a hub 30 pivoted on a shaft 3 I. A pawl 32 secured to one of the arms engages a ratchet 33 on the roll to restrain it from rearward motion. These rolls permit free forward movement of the web but prevent any rearward movement. Beyond the rolls the web passes over a guide plate 34. v

The cutting mechanism comprises a blade 40 and a slotted member 4| carried respectively by arms 42 and 43. Arm 42 is free on a shaft 44, while arm 43 is pinned to the shaft. A link 45 connected to arm 42, and a link 46 connected to an arm on the shaft 44 extending oppositely from arm 43, are both connected to the forward end of a lever 41 pivoted at 48 to the frame I I). This lever carries a block 49 adapted to engage the surface of a constantly rotating drop off cam 50 and, as shown in Fig. 1, to give a very rapid movement to the lever, and consequently to the cutting mechanism, under the influence of a spring 5| when the drop off edge of the cam passes the block. An arm 52 is pivoted to the lever 41 at 53 (Figs. 2 and 6), and is itself pivoted at 54 to a link 55 swinging on a shaft 56 mounted on the frame. The free end of the arm 52 bears a cam roll 51 adapted under certain conditions to contact with the cam 50.

The operation of the cutting mechanism as thus far described will now be considered. It is convenient to start with the position of Fig. 3, in which the roll 51 is bearing on cam 50, keeping the block 49 slightly spaced from the cam. As

the roll rides over the drop-off shoulder 58 it permits the block 49 to settle down in contact with the cam without producing any substantial movement of the cutting members. When the shoulder 58 reaches the block 49 it has passed roll 5! completely, so that the block drops off suddenly under the influence of the spring 5 I. Initially the downward movement of lever 41, and consequently the closing movement of the cutting members, will be one of steady acceleration by the spring without any restraint from any other parts. As the cutting members near their closed positions, however, the llnkage 52, straightens out, as shown 55 in Fig. 1, giving a definite limit to the travel of lever 41 towards the cam. This limit is taken so that the roll I! and the block 43 will never strike the cam in their descent. It will be apparent from a comparison of Figs. 3 and 1 that the stoppage of motion of the cutters occurs gradually, the linkage at first exerting substantially no restraint upon the lever and finally bringing it to rest with substantially a harmonic motion.

The linkage described has a definite advantage over that shown in the prior application Serial No. 644,066 in the manner in which the mechanism is returned to its inactive position after the completion of the cutting operation. Referring particularly to Fig. 2, it will be seen that contact of the roll 51 with the restoring portion of cam 50 occurs in such a direction as to create a turning moment about both of the pivots 48 and 53. The raising of lever 41 is not done directly, but is brought about by the raising of pivot 53 as the roll 51 causes arm 52 to revolve about that pivot and fold up the linkage 52, 55. All possibility of the linkage becoming stuck on dead center is avoided by reason of the conversion of the force between the cam and the roll into turning moments rather than into a straight push.

Associated with the cutting mechanism is a brake for preventing overrun of the web which would otherwise be likely to occur on account of the high speed at which the apparatus is generally operated. In the embodiment shown this brake is in the form of a block 60 (Fig. 3) carried by an arm 8| pivoted on the shaft 44. A set screw 62 on the arm BI is positioned for contact with an arm 63 secured to the shaft 44, so that as the shaft moves in the direction which opens the cutters the block 60 will be moved up as in Fig. 3. When the cutters close, the block will be allowed to drop under its own weight, assisted if desired by a spring 64 to press the web against the support 22.

Also associated with the cutting mechanism is a device which is of great utility in cases where the apparatus is used on several types of wrapping material. Different wrapping materials such as ordinary paper, waxed paper, or the various cellulosic derivatives, have different characteristics when drawn from a roll and passed through the described apparatus. It is intended in the embodiment shown that the primary feed of the web shall be accomplished by one or more grippers 65 (Fig. 1), mounted on chains 66 which pass around pulleys 61 and 68 as fully described in the prior Patents 1,953,195 and 1,953,196 referred to, and the description of the action of the web will for convenience have reference to that type of feed. It will be understood, however, that the utility of the improvement is not limited to this specific adaptation. In the web feed of the prior patents the gripper 65 picks up the leading end of the web, which projects slightly beyond the support 34, just before the gripper starts to tum around the pulley 88. The initial engagement between the gripper and the web is thus obtained while the gripper is moving at right angles to the web and, therefore, has no substantial component of motion in the direction in which the web is to travel. The engagement is thus without any shock, and the acceleration of the web as the gripper turns around the pulley is steady. In order for this type of feed to operate successfully the freshly cut end of the web must be presented in accurate position to be picked up by the gripper in its motion. Different wrapping materials have different curling tendencies, and

with prior devices it has been diillcult to make a cutting mechanism designed for one type of material operate successfully on another type.

In the present case a very simple control for the freshly severed end of the web has been provided, in the form of a guard plate 10 (Figs. 4 and 5) mounted on an arm II. The arm is pivoted at 12 to an arm 13 secured to shaft 31, and is provided with a spring 14 stretched between a rearward extension of the arm and a handle 15 on the If) hub 30. When the cutters are open as in Fig. 3, the guard plate rests upon the edge of the support 34. When the cutters close the arm 43 contacts with the guard plate and raises it (Fig. 2), so that the web may extend straight to the cutters with- 15 out interference. In order to vary the manner of engagement between the guard plate and the support 34, in the manner shown by a comparison of Figs. 4 and 5, an arm 16 is secured to the shaft 3| and has a slot 11 in its end to receive a sta- 20 tionary' pin 18. A spring 19 draws this arm clockwise, as viewed in these figures, to the limit permitted by an adjusting screw 80 threaded into the arm so that it forms in effect one adjustable end for the slot I1. By turning this adjusting screw the guard plate may be shifted from its retracted position of Fig. 4 to the position of Fig.

5 in which it overlies the end of the support. Any intermediate position may of course also be assumed. A paper position about as shown in Fig. 5 is generally desired, but this does not mean that the guard plate should always assume that position. As indicated in Fig. 4, different types of paper may tend to assume varying positions for a given setting of the guard plate, and in any specific instance it may be necessary to move the plate either forward or back from an assumed central position in order to give the slant desired to the end of the web.

In threading a fresh web of wrapping material through the cutting mechanism the upper roll 28 is raised by means of the handle 15. At the same time the ends of the shaft on which this roll is mounted strike the under sides of the arms H and raise the guard plate clear of the support 34. With the wrapping material in place and the machine started, the gripper 65 will pick up the leading end of the web and accelerate it smoothly as the gripper passes around the sprocket 68. At the same time the web will be raised from the support 34 so as to extend in a straight line from the roll 24 to the gripper, this being permitted by the' elevation of guard plate "Ill. After a sufficient length .of web has been drawn out by the gripper the cutters close, being accelerated rapidly into cutting position and then decelerated smoothly to rest in the manner described. While the gripper continues its uninterrupted motion with the severed sheet, the guard plate 10 descends to carry against the support 34 the freshly cut end of the sheet, stopped in its motion by brake 60 and prevented from backward movement by the ratchet mounting of the rolls. The brake 60, being located on the side of the rolls 24, 28 remote from the cutters, prevents the formation of any slack due to overtravel of the rolls when the machine is operated at high speeds. The formation of slack between the rolls and the cutters would prevent the proper operation of the cutting mechanism, or would make the position of the leading edge of the cut web uncertain, so that the grippers would not function properly. Assuming the screw 30 to be properly adjusted, the end of the web will be positioned 7 in the correct position to be picked up by the next gripper.

What I claim is:

1. A cam mechanism for web severing mechanism and the like, comprising a drop-off cam, a

cam follower, a linkage connected to the cam follower and having at least three pivot points. one movable with the cam follower, one fixed, and the third movable into a straight line with the other two when the follower drops off the high point of the cam to check the fall of the follower, and means operating on-the linkage to shift said third pivot back to its original position.

2. A cam mechanism for web severing mechanism and the like, comprising a drop-off cam, a cam follower, a rigid linkage connected to the severing mechanism and having its parts proportioned and arranged to permit substantially free movement of the follower at the instant of release and movable progressively into a. dead center position to decelerate the follower positively and rapidly with a substantially harmonic motion so that it is brought smoothly to rest at a position predetermined by the linkage, and means operable on the linkage to move it positively out of its dead center position to permit the return 'of the follower.

3. A cam mechanism for web severing mechanism and the like, comprising a frame, a cam having a drop-01f shoulder and a restoring portion, an arm pivoted tothe frame and coupled to the web severing mechanism, a link pivoted to the frame, a lever pivoted to the arm and to the link to form therewith a restraining means limiting the travel of the arm toward the cam but exerting substantially no restraint upon the arm when the latter is in its elevated position, and means, including a cam engaging portion carried by the lever to turn the lever positively by engagement with the restoring portion of the cam, for causing said arm to be raised and lowered in accordance with the conformation of the cam.

4. A cam mechanism for web severing mechanism and the like, comprising a cam having a drop-off shoulder and a restoring portion, cutting mechanism, a follower coupled to the cutting mechanism to operateit when passed by the drop-off shoulder of the cam, a folding linkage operating when straightened to limit the travel of the follower towards the cam, and means operated by the restoring portion of the cam for restoring the follower and refolding the linkage.

5. A cam mechanism for web severing mechanism and the like, comprising a frame, a cam mounted for rotation in the frame and having a drop-ofi' portion and a restoring portion, an arm pivoted to the frame and coupled to the web severing mechanism, a camfollowing block carried by the arm, a link pivoted to the frame, a

lever pivoted at an intermediate portion of its 5 length to the arm and at one end to the link, a cam roll carried by the second end of the lever, and a spring urging the arm towards the cam, the parts, being proportioned and arranged so that the roll normally keeps the block from contact with the cam, allowing the block to bear on the cam adjacent the drop-off shoulder only and as the roll itself passes over said shoulder, and so that the straightening of the linkage described will limit the movement of the roll and block toward the cam after passing over the drop-off shoulder, the contact of the restoring portion of the cam with the roll serving to fold said linkage out of its straight -line position and to elevate the roll'and block into position to pass once more over the drop-of! shoulder.

6. A web severing mechanism comprising a web supporting plate, means for severing a web along a line spaced beyond the end of the supporting plate to aiford an overhanging portion of the web, a gripper for drawing out successive lengths of web constructed and arranged to engage the overhanging part of the web, and means for varying the angle of inclination of said overhanging part. I

'I. A web severing, mechanism comprising, a web supporting plate, means for severing arweb along a line spaced beyond the end of the supporting plate to aiford an overhanging portion of the web, a gripper for drawing out successive lengths of web constructed and arranged to engage the overhanging part of the web, and a guard plate yieldably pressed against the web adjacent the end of the support and inclined at an angle thereto to control the angle of inclina- 40 tion of the overhanging part of the web.

8 A web severing mechanism comprising, a web supporting plate, means for severing a web along a line spaced beyond the end of the supporting plate to afford an overhanging portion of the web, a gripper for drawing out successive lengths of web constructed and arranged to engage the overhanging part of the web, a guard plate yieldably pressed against the web adjacent the end of the support and inclined at an angle thereto, and means for adjusting the guard plate relative to the end of the support to control the position of the overhanging portion for diflerent types of wrappers.

WILLIAM HOPPE.

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