US3393593A

US3393593A - Material feed apparatus

Info

Publication number: US3393593A
Application number: US573621A
Authority: US
Inventors: Eyberger Harry
Original assignee: Magnetic Metals Corp
Current assignee: Magnetic Metals Corp
Priority date: 1966-08-19
Filing date: 1966-08-19
Publication date: 1968-07-23
Anticipated expiration: 1985-07-23
Also published as: DE1602511A1; GB1176963A; CH482542A

Description

July 23, 1968 H. EYBERGER MATERIAL FEED APPARATUS 6 Sheets-Sheet 1 Filed Aug. 19, 1966 FIG.

ATTORNEYS July 23, 1968 H. EYBERGER 3,393,593

MATERIAL FEED APPARATUS Filed Aug. 19, 1966 6 Sheets-Sheet 2.

FIG. 2.

INVENI' OR Harry Eyberger ATTORNEYS July 23, 1968 H. EYBERGER MATERIAL FEED APPARATUS 6 Sheets-Sheet 4 Filed Aug. 19, 1966 INVENTOR Harry Eyberger BY M M M ATTORNEYS July 23, 1968 H. EYBERGER 3,393,593

MATBR IAL FEED APPARATUS Filed Aug. 19, 1966 6 Sheets-Sheet 5 FIG. 8.

INVENTOR Harry Eyberge r BY fl ml, 4441 1 412 ATTORNEYS July 23, 1968 H. EYBERGER MATERIAL FEED APPARATUS 6 Sheets-Sheet 13 Filed Aug. 19, 1966 FIG. 9.

INVENTOR Harry Eyberger ATTORNEYS 1 3,393,593 r v MATERIAL FEED APPARATUS Harry Eyberger, Cherry Hill, N.J., assignor to Magnetic Metals Company, Camden, NJ. Continuation-impart of application Ser. No. 568,690,

May 24, 1966. This application Aug. 19, 1966, Ser; No. 573,621 v v 9 Claims. (Cl. 83-241) This application is a continuation-in-part of copending US. application Serial No. 568,690 filed, May 24, 1966 and now U.S. Patent No. 3,333,497 issued. Aug. 1, 1967, which in turn, is a continuation in-part of US. application Ser. No. 442,,026, filed Mar. 23, 1965 and now abandoned. i. r, 1

- This invention relates to apparatus vfor feeding material to a machine or the like, and. more particularly pertains to apparatus for feeding strip or sheet material to a punch press or similar machine.

In the formation of complex and intricately shaped parts by meansiof a punch press, it is common practice to punch only a small portion of the entire pattern at each of successive stations. This requires that the apparatus controlling the feed of the material to the punch press be capable 'ofcontrolling accurately the amount by which the material is fed for each cycle of operation in order that the punching operation as carried out at any station after the first shall register properly with the punches previously made. In many instances, it is necessary that the feed travel of the' strip be controlled within a tolerance of about one one-thousandth of an inch.

One rior art apparatus used for thecontrol of the feed strip material to a punch press makes use of electromagnetically operated clutches and brakes. In such apparatus, a friction brake is employed which is continually effective to apply a braking force to the feed rolls. When it is desired to advance the strip for a successive punching operation, a clutch is engaged, thereby enabling driving power to be applied thereto through the feed rolls so that they are rotated against the braking action applied by the brakeI When the driving power is removed by, disengaging the clutch, the'feed rolls are brought to a quick stop by the brake. The disadvantages of this prior art apparatus are that the brake surfaces tend to glaze and wear so that the effectiveness of the brake varies with time with the result that the braking force opposing the driving force applied through the clutch is not uniform. Also, the grabbing effect of the clutch on the feed rolls is not uniform over long periods of time, and the clutch may tend to slip. In addition, the sudden application and removal of turning moment to the feed rolls is not gradual when brakes and clutches are used, and this, together with the disadvantages previously mentioned, tends to produce appreciable error in the amount of rotational motion imparted to the feed roll for each cycle of operation. Thus, it'becomes extremely difficult to ensure that the strip will be fed the correct amount.

Still other prior art apparatus has been devised for the feeding of strip material, butapparatus which overcomes the disadvantages just stated has the disadvantage of being very costly. Accordingly, it is an aspect of this invention to provide apparatus for controlling the feeding of strip material which'is not only highly accurate but is also low in cost.

Another advantage which is obtained through use of the feed apparatus-of the present invention is the elimination, in some instances, of the' need for registration holes in the strip material. More specifically, the lack of high accuracy of some of the prior art apparatus makes it necessary to provide registration holes in the strip, which holes are spaced a distance equal to the amount that the material is to be advanced for each cycle of operation of the press. Corresponding pins are provided near the die of the punch press and accurate registration of the strip is obtainable only by providing means which ensures that the holes in the strip will each receive a respective one of the pins. In other words, the feed mechanism of such prior art apparatus advances the strip only approximately to the desired position, and thereafter the strip is moved into the exact desired position by registering at least one hole with a corresponding pin. Byuse of the apparatus of the present invention, however, the accuracy which ,is obtainable is of such a high order that the registration holes and corresponding pins can be entirely dispensed with in many instances. 7 I

-When registration holes and pins are employed, it then becomes necessary to release the rollers which feed the strip material just prior to the actual punchingoperation so that the strip can be shifted in position slightly and thus properly aligned With the registering pins. Of course, with the apparatus of the present invention, which makes possible the elimination of such registering holes and registering pins in some instances, this release of the strip material by the rollers to effect proper registration is not required. It is, however, desirable to release the rollers momentarily during some portion of the cycle of operation in order that the strip can periodically be aligned with the die in a direction transverse to the direction of strip feed. As Will be described in detail later, one aspect of this invention is the provision of means which releases the feed rolls but does so only when the strip is securely held by the stripper. Thus, even though release of the rollers is desirable with the improved apparatus of this invention, this can still be effectively carried out without requiring any additional means to hold the strip at the time the rollers are released Since this operation is automatically effected during that portion of the cycle when the strip is securely held by the punch.

It is at times still desirable, even With the apparatus of the present invention, to use registering holes in the strip material and corresponding pins in the die. This may be desirable particularly Where extremely high accuracy is required and Where it is desired to provide for very accurate registration of the strip material in a lateral direction, i.e. a direction transverse to the direction of feed of the strip material.

Described briefly, the present invention comprises an input shaft which is rotated with a constant angular velocity from an output shaft of the punch press making a complete revolution for each cycle of operation of the press, and an output shaft which dwells throughout a predetermined substantial part of the cycle of rotation of the input shaft and drives the rollers feeding the strip material to the punch press. As the input shaft makes one complete revolution corresponding to a cycle of operation of the press, the feed rollers remain motionless during a significant part of the cycle of rotation, thereby making possible the exact alignment of the strip material with the pun-ch of the press and allowing time also for the actual punching operation and the withdrawal of the punch after the punching operation is completed.

In the aforesaid US. application S.N. 442,026, there is disclosed apparatus constructed in conformity with the above-mentioned requirements and comprising, as one embodiment thereof, -a three-gear mechanism in which the input gear is eccentrically mounted and operated by an output shaft of the punch press mechanism through one complete revolution for each complete cycle of operation of the press. The input gear drives an idler gear, and the idler gear in turn drives an output gear. The relationship of the gears is such that the output gear remains substantially motionless throughout a predetermined portion of the rotational cycle of the input gear, thereby making possible the desired dwell of the feed rollers. An alternative embodiment of the invention disclosed in Serial No. 442,026 comprises a multiple Geneva cam mechanism, the input shaft of which rotates with a constant angular velocity, while the output shaft at times dwells, thereby again making possible a predetermined amount of dwell time of the feed rollers during each cycle of operation of the punch press.

Although the several embodiments of the invention illustrated in the aforesaid US. application S.N. 442,026 have been found to be entirely practical and have been put to commercial use, it is nevertheless found at times to be desirable to provide a greater amount of dwell time than is possible with either of the mechanisms illustrated in the copending patent application referred to above. One significant advantage resulting from the ability to provide a longer dwell time is that of a decrease in maintenance costs associated with the die used in the punch press for reasons which will be explained more fully hereafter. To

accomplish this function of providing a greater dwell time,

it is contemplated by the present invention to use either the three-gear mechanism or the Geneva cam mechanism as disclosed in the aforesaid US. application S.N. 442,026 and to ope-ratively connect to the input of such mechanism an elliptical gear drive mechanism so that the input shaft of the three-gear mechanism, or the Geneva cam mechanism, as the case may be, does not rotate with a constant angular velocity but instead rotates with a variable angular velocity. The elliptical gear mechanism is so coupled to the three-gear mechanism (or to the Geneva cam mechanism) that the output elliptic-a1 gear which drives the input of the three-gear mechanism (or the Geneva cam mechanism) rotates with its minimum angular velocity at a time when the three-gear mechanism (or the Geneva cam mechanism) is producing dwell of its output shaft. Thus, by rotating the input shaft at a slower speed during the dwell time than otherwise, it is possible to length the dwell time significantly while still maintaining the high degree of accuracy which is possible with the mechanisms disclosed in my prior application Serial No. 442,026.

It is accordingly an object of this invention to provide new and improved means for the feeding of strip or sheet mate-rial to a machine such as a punch press, with the amount of advance of the material for each cycle being accurately maintained within close limits.

It is a further object of the invention to provide strip feed apparatus for a punch press which is of relatively low cost as compared to the prior art apparatus having corresponding accuracy and which is relatively simple to manufacture and requires a minimum of maintenance.

It is a further object of this invention to provide apparatus for the feeding of strip material to a machine such as a punch press where the accuracy of feed is of such a high order that no guide holes and guide pins are required to position the strip material accurately.

It is another object of the invention to provide a feed mechanism for -a punch press or the like having feed rolls which are subjected to only gradual acceleration and deceleration.

It is another object of this invention to provide apparatus for the feeding of strip material to a punch press or the like which includes means for releasing the feed rolls momentarily at the time the material is securely held between the die shoe and punch.

It is a further object of the invention to provide apparatus for the feeding of strip material to a punch press or the like which provides considerably more dwell time of the feed rolls than does the apparatus disclosed in my corresponding applications Serial No. 568,690 and Serial No. 442,026 referred to previously.

Other objects, purposes, and characteristic features of the invention will in part be obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention, reference will be made to the accompanying drawings in which like reference characters designate corresponding parts throughout the several views.

In the drawings:

FIGURE 1 is a perspective view of a typical punch press having the feed drive mechanism of the present invention applied thereto;

FIGURE 2 is a plan vie-w of a three-gear mechanism forming a portion of the strip feed apparatus of the present invention;

FIGURE 3 is a side view of the apparatus shown in FIGURE 2;

FIGURES 3A and 3B comprise front and side views, respectively, of the eccentric gear drive portion of the apparatus shown in FIGURES 2 and 3;

FIGURE 4 is a view of a Geneva cam mechanism forming a portion of an alternative embodiment of the strip feed apparatus of the present invention;

FIGURE 5 is a sectional side view of the Geneva cam mechanism of FIGURE 4 taken along the section line 5-5;

FIGURE 6 is a view of the cam element shown in FIGURES 4 and 5;

FIGURE 7 is a diagrammatic illustration showing the sequential operation of the mechanism of the present invention during a complete cycle of operation of the punch ress;

FIGURE 8 is a plan view of the elliptical gear drive mechanism of the present invention;

FIGURE 9 is a sectional view of the apparatus shown in FIGURE 8 and taken along the section line 99; and

FIGURE 10 diagrammatically illustrates the interrelationship between the elliptical gear mechanism and the dwell-producing mechanism such as the three-gear mechanism.

FIGURE 1 illustrates a typical punch press comprising a base or frame 10 supporting a bed 11 to which the die shoe 12 is bolted. A plurality of slides or rams 13 are adapted to move up and down with respect to the bed 11. A punch 14 is supported by member 15 which is supported by slides '13. A source of motive power such as an electric motor (not shown) may be used to move the slides up and down through each of successive cycles of operation. Any of the numerous well-known types of mechanisms may be coupled between the motor and the slides such as a crank, cam, eccentric shaft, toggle joint, etc.

From the general description given previously, it is apparent that the present invention has particular utility when used in connection with a multiple press having a gang of dies which are arranged to perform a series of operations in sequence on a piece of work. To simplify the illustration, however, only a single die shoe 12 and punch 14 are shown in FIGURE 1.

The material being acted upon by the punch press may be fed to the die members by a pair of feed rolls (not shown), one of which is rotated as a result of rotation of the shaft 16 which is driven by chain 17. The two feed rolls are urged tightly against each other by means of springs 18 which bear downwardly on the upper of the two rollers, so that strip material which is frictionally engaged thereby can be fed toward the punch.

A means is also provided for momentarily relieving the pressure of the feed rolls upon the strip. More specifically, an arm 19 is provided which is pivoted about a bearing 20 and is at times rotated clockwise about such bearing by reason of the fact that a push rod 21 is periodically and momentarily urged upwardly. The manner in which the push rod is actuated will subsequently be described in greater detail. In any event, the result of this rotation of lever 19 is a counter-clockwise rotation of lever 22 to which lever 19 is mechanically coupled by rod 23. The counter-clockwise rotation of lever 22 about its bearing 24 results in the raising of the upper feed roll with reference to the lower feed roll so that the strip material or the like being fedto thepunches of the press is momentarily released. l The gear drive mechanism of a first embodiment of the invention is housed within a case 2-5supported.by:L- shaped brackets 26, each'ofwhich is bolted to the case 25 and also to the side of the base of the punch press. The output shaft of thefgear drive mechanismhas affixed thereto a pinion 27 which is coupled to gear 28 by means of chain 17. For each cycle of operation of the press 33, there is a predetermined amount of dwell as will later be described. The predetermined amount of angular rotation of pinion 27 occurring each cycle is transl-ated'into a predetermined amount of rotation'of gear 28 which is'in turn translated into a given amount of linear travel of-the strip material toward the punch.

Also aflixed to the's'ide' of frame 10 is a case 84 which houses a planetary gear mechanism having an input shaft (not shown in FIGURE '1) and an out-put shaft-supporting piniori 85'. Pinion 85 is coupled to an'input shaft 33 of the threegear mechanism housed in case 25 by means ofchain 85dwhich passes over both pinion 85 and-pinion 85b on input shaft 33. A punch press is normally provided with an output shaft that is coupled to the source of motive power in such away that" it makes one complete'revolution for each complete punching cycle ofthe press. Such a shaft is provided to facilitate the coupling'thereto of one of the prior art types of'feedmechanismls. This shaft (not shown) is directly coupled to an input shaft of the elliptical gear mechanism to be described in detail subsequently. Consequently, for each'cycle of operation of the press, the iriputshaft (not shown of the elliptical gear mechanism makes one'full revolution and the associ ated output gear directly coupled to pinion 85 similarly makes one complete revolution but with a variable 'an'g'ular velocitywhereas the input shaft rotates with aconstant velocity. This produces one full revolutionof pinion'85b and shaft '33. Pinion 27 rotates through a predetermined angle, but this pinion nevertheless 'dw'ells throughout a substantial part of the cycle with a resulting stoppage'in the feed of the strip material thereby permitting registration of the strip With the die andalso'the actualpunchiiig operation. v j' The three-gear drive mechanism driven by the elliptical gear mechanism according to one embodiment of the pres ent invention is illustrated in greater detail in' FIGURES 2 and 3. FIGURE 2 is aplan view .in cross section showing the side walls 30 and end walls 31 of the casing which encloses the various. partsof the gear drivernechanism. FIGURE 3 illustrates the bottom plate 32 and the top plate 33 as well as the end walls 31. The casingcomprises generally a box-like structurewhich is preferably substantially entirelyclosed so as to protect the various gears enclosed thereby and to protect also the operator of the ch n 1 v Referring to FIGURE 2, an inputshaft 33 is provided which rotates within a bearingsurface-defined inthe side wall 30 of the casing. The shaft 33 is, formed in part of a cylindrical shaft portion 34 which is splined at 35 so as to permit the shaft to be directly coupled to-an output shaft (not shown) of the punch press which outputshaft, as previously explained, makes one complete revolution for each cycle of operation of the punch press. Shaft 33 also comprises a circular portion 36 having'a circularrecess at 37 which is eccentrically located relativeto the axis of shaft 33 and is adapted to receive a splined shaft 38. v

. The details of the shaft 33 and splined shaft. 38 are shown in greater detail in FIGURES SA-and 3B. The shaft 33 is shown together with its circular portion-36 having the circular recess at 37 The eccentric shaft 33 is also illustrated as having a transverse slot at 40which communicates with the circular hole 37. Rotation of the shaft 38 within the circularhole 37. is prevented bymeans of the key 41 which abuts against the shoulder 42 formed in the end of shaft 38. Key -41 is held in position in slot byrmeans of two machine screws 43which are threaded into tapped holes provided in the circular portion 36'of shaft 33. t

It will be readily evident that the eccentric location of the hole 37 in circular member 36 with respect to the axis of rotation of shaft 33 produces an eccentric operation of the shaft 38 as shaft 33 is rotated by the output shaft of the punch press.

FIGURES 3A and. 3B relate particularly to the eccentric drive associated with input shaft 33,.but FIG- URE 3 shows that the opposite end of splined shaft 38 is supported in a similar manner at its opposite'end by an eccentric shaft drive 45 which is similarly journalled in a bearing surface 46 formed in the side wall '30 of the casing;

Keyed to shaft 38 is a pinion gear 47 whose teeth mesh with an-idler gear 48 which is rotatable about a shaft 49. Gear 48, in turn, drives gear 50 whichis keyed to shaft 51 journalled within suitable bearings provided in apertures in the side walls 30 of the casing. Rotation of shaft 33 results in rotation of gear 47 but with the axis of: rotation of gear 47 moving eccentrically with respect to the axis of shaft 33. The rotation of gear 47 nevertheless produces rotation of gear 48 which, in turn, rotates gear 50 and with it the shaft 51 to which is keyed a pinion gear 52 which meshes with a gear 53 splined to an output shaft 54. Shaft 54 is similarly journalled within suitable bearings and has keyed thereto at one end a pinion gear 27 which is illustrated in FIGURE 1 as driving the chain 17.

FIGURE 3 shows

shafts

38 and 49 coupled together by one or more links Each link is free to rotate both with respect to shaft 38 and with respect to shaft 49. Similarly, shaft 49 is coupled to shaft 51 by one or more links 61. Links 61 are similarly free to rotate relative to both shafts 49 and 51. Thrust bearings are shown for the output shaft 51 at 6-2-66. Similar thrust bearings are provided for shaft 38 at 67-70, while thrust bearings 71 and 72 are provided for shaft 33. 'With respect to shaft 49, thrust bearings are provided at 7580.

Referring to FIGURE 3, it can be seen that rotation of'gear 47 not only rotates gear 48, but also, by reason of the eccentricity of gear 47, and by reason of the fact that shaft 33 is directly coupled to shaft 49 by links 60, results in a rotation of the axis of shaft 49 about the axis of shaft 51.

1 From FIGURE 3 it can be seen that the direction and rateof rotation of shaft 49 about the axis of shaft 51' is dependent upon the angular position of eccentric gear 47. When the axes of

shafts

38, 33, and 49 are all in alignment, i.e. lying in the same plane, the rate of rotation of shaft 49 about the axis of shaft 51 reduces to zero. Such alignment occurs twice per revolution of shaft 33, once when the axis of shaft 38 lies between the axes of shafts 3-3 and 49, and once when it lies outside. From either of these two reference points, shaft 49 rotates in one direction about shaft 5 1 for one-half revolution of eccentric gear 47 and in the opposite direction for the remaining half revolution. More specifically, starting from the position where axes of

shafts

38, 33, and 49 are aligned but with the axis of shaft 38 lying between the other two axes, and assuming that eccentric gear 47 is rotating in a counter-clockwise direction, the axis of shaft 49 will from that point on begin to rotate in a counterclockwise direction about shaft 51 and will continue to do so until the three shafts are again aligned but with the axis of shaft 38 now lying outside of the line segment joining the axes of shafts 49 and 51. From that point on and back to the initial position, shaft 49 rotates in a clockwise direction about shaft 51.

The rotation of the axis of shaft 49 about shaft 51, coupled with the rotation of, gear 48 itself combine to produce a variable velocity of the output gear =50. More specifically, assume that the eccentric gear 47 starts rotating counter-clockwise from the position where the three axes mentioned above are all in alignment but with the axis 38 lying without the axes of

shaft

33 and 49, there will simultaneously be a clockwise rotation of gear 48 and a clockwise rotation of the axis of shaft 49 about the axis of shaft 51. By suitable adjustment of the various parameters involved, particularly the ratios of the several gears, the eccentricity of gear 47, and the distance between the axes of shafts 33 nd 51, there will be a range of rotation of gear 47 which will result in no rotation of gear 50 and thus no rotation of the output gear 27. Apparently, though a given range of rotation of eccentric gear 47, the amount of rotation which would otherwise be imparted to gear 50 as a result of the rotation of gear 48 is almost precisely compensated for by the rotation of the axis of shaft 49 about the axis of shaft 51 so that gear 48, although rotating slightly, is in effect at the same time rotating about gear 50 with the result that gear 50 remains motionless.

Extensive experimentation has shown that numerous combinations of parameters will result in a satisfactory amount of dwell of the output gear 50. One specific combination of such parameters which has been found to be highly useful in producing a substantial amount of dwell at the output gear is that wherein the eccentric gear 47 has a diameter of two inches, the idler gear 48 a diameter of six inches, and the output gear 50 a diameter of four inches. Moreover, the spacing between the axes of the eccentric gear 47 and output gear 50 is chosen to be seven and three-quarter inches and the eccentricity of the input gear 47 is equal to 0.625 inch. With this combination of parameters, it is found that the output gear 50 will dwell through 95 of rotation of the input gear 47. Although the selection of parameters is not highly critical, it is nevertheless of real importance since combinations of parameters can readily be found that will produce no dwell of gear 50 and other combinations will produce a momentary reversal of gear 50.

FIGURE illustrates diagrammatically the eccentric input gear 47, idler gear 48, and output gear 50 in the positions they assume at a particular portion of the operating cycle. Various parameters which affect the amount of dwell are designated with appropriate reference characters. Thus, A designates the axis of revolution of the eccentric input gear 47 whose center is at D; B denotes the point of contact between the

gears

47 and 48; C, the point of contact between

gears

48 and 50; and E, the axis of rotation of output gear 50. The reference characters r r and r designate the respective radii of

gears

47, 48, and 50.

It has been determined that dwell occurs when the points A, B, and C of FIGURE 5 all lie along the same straight line and when angle DAB is equal to 90. Actually, dwell of the output gear starts somewhat before the time that angle DAB reaches 90 and extends beyond that point, but it has nevertheless been found that dwell will occur when both of the above conditions are simultaneously met. The foregoing conditions further make it possible to determine the optimum distance between points A and E for maximum dwell. Thus, from the cosine formula, it can be determined that the distance of separation, AE, equals:

It has further been determined that, in general, the duration of dwell increases as the eccentricity 2 increases. However, there are practical limits to the amount of eccentricity since, if this becomes excessive, there may be a slight reversal of the direction of rotation of output gear 50 and it may also become difficult to turn input gear 47 through a part of its cycle. As one example, if

the relative sizes of the several gears is such that r equals one inch, r equals 3 inches, and r equals two inches, then the input gear 47 becomes difficult to turn when the eccentricity e is greater than .875 inch.

In my prior copending application S.N. 442,026, it is disclosed that the input shaft 33 of the three-gear mechanism is rotated with a constant angular velocity by virtue of its direct coupling to the output shaft of the punch press which similarly rotates with a constant velocity and makes one complete revolution for each cycle of operation of the press. An important feature of the present invention, however, is that the shaft 33 of the threegear mechanism is driven with a variable velocity by reason of its being operatively connected to the output gear of an elliptical gear mechanism. This elliptical gear mechanism is shown in detail in FIGURES 8 and 9, with FIG- URE 8 comprising a sectional plan view of the gear mechanism, and FIGURE 9 comprising a sectional elevational view of the same mechanism.

FIGURE 8 shows the opposing side walls and 131 of the case 84 (see FIGURE 1), and these side walls provide bearing support for two

shafts

132 and 133, both of which are journalled in the side walls by needle bearings as illustrated, for example, at 134. Shaft 132 protrudes through side Wall 30 and is provided with a keyway 135 to permit this shaft to be directly coupled to the output shaft of the press (not shown) which is operated with constant angular velocity as previously described. Shaft 132 also has keyed thereto an elliptical gear 136 and a circular gear 137, and these two gears are separated by spacer 138. Gear 137 is suitably spaced from the inner surface of wall 131 by spacer 139 and a split spacer 140, the two halves of which are connected together by bolts 141. Shaft 133 has secured thereto an elliptical gear 142 and also a circular gear 143, and these are spaced by the spacer 144. A predetermined amount of spacing is provided between circular gear 143 and the adjacent surface of side wall 131 by means of spacer 145.

The arrangement of the various spacers is such that the

elliptical gears

136 and 142 are in mesh, whereas the

circular gears

137 and 143 are out of mesh. However, it is apparent that by removing the split spacer elements 140, gears 136 and 137 together with spacer 138 can be laterally moved to the right in FIGURE 8 along shaft 132 to place circular gear 137 in mesh with the corresponding circular gear 143, with the result that the

elliptical gears

136 and 142 will then no longer mesh with each other. When this is done, the split spacer elements 140 are moved to the left of gear 136 so as to maintain the proper spacing between that gear and the adjacent surface of side wall 130. The reason for making this adjustment possible is to facilitate having, optionally, a direct gear coupling between

shafts

132 and 133, thereby eliminating the effects of the elliptical gear drive mechanism with the result that the input shaft 33 of the three-gear mechanism will then rotate with constant angular velocity just as described in my copending application S.N. 442,026. However, for the purposes of describing the present invention, it will be assumed that elliptical gear 136 is positioned to be in engagement with elliptical gear 142 to thereby provide a varying angular velocity of shaft 133 in response to a constant angular velocity of shaft 132.

Shaft 133 has keyed thereto the pinion 85 which has already been described in connection with FIGURE 1. Since shaft 132 is to be directly coupled to the output shaft of the punch press which rotates with uniform angular velocity, it is apparent that shaft 133 will rotate with a variable velocity, at times rotating with an angular velocity significantly less than that of shaft 132 while at other times rotating with an angular velocity greater than that of shaft 132. It will be apparent to one skilled in the art that the extent of the difference in rotational speed of the shafts is dependent upon the eccentricity of the

elliptical gears

136 and 142.

FIGURE 10 illustrates the desired relationship between the elliptical gear mechanism of FIGURES-8 and 9 and the three-gear mechanism previously described in connection with FIGURES 2, 3, 3A and 3B. As mentioned previously, dwell will occur with respect to the output gear 49 of the three-gear mechanism when the points A, B and C of FIGURE 10 lie in a straight line and when the angle DAB is a right angle. It will also be apparent that the amount of dwell which is experienced for positions of the gears 47-49 to either side of that satisfying these conditions as a function of the amount of angular rotation of shaft 132 of the elliptical gear mechanism of FIGURE 8, must be dependent upon the angular velocity of shaft 133 at the time that the stated conditions are fulfilled. Clearly, the amount of dwell will be increased if the angular velocity of shaft 133 is at a minimum at thetime the conditions of dwell of the three-gear mechanism are satisfied. This requires that the effective radius of the elliptical gear 142 relative to the point of contact with elliptical gear 136 be at its maximum value, and with the corresponding effective reduction of elliptical gear 136 at its maximum value at the very time that the dwell conditions of three-gear mechanism are met, namely, that points A, B and C lie in the same straight line and that angle DAB be substantially 90.

It, will also be apparent that the amount of increased dwell that is obtainable through the use of the

elliptical gears

136 and 142 is dependent upon their eccentricity. A limiting factor in establishing the amount of eccentricity resides in the fact that the greater the amount of eccentricity, the greater must be the acceleration and deceleration of the shaft 133* and thus also of shaft 33. If these are increased to too high a value, undue strain and wear on the various parts of the mechanism will result by reason of the large acceleration and'deceleration factors involved in the movement of the heavy parts such as the feed rolls which have a high moment of inertia. It has been found in actual practice, however, that a dwell time equivalent to 180 of the complete punch press cyclecan be provided for with the use of elliptical gears having sufficient eccentricity. This amount of dwell time is to be compared to the approximately 90 of dwell time that is obtainable when the three-gear mechanism is used without a cooperating elliptical gear mechanism An alternative embodiment of my invention is illustrated, in part, in FIGURES 4, 5 and 6 which illustrate a multiple Geneva cam mechanism which may be substi tuted for the three-gear mechanism of the embodiment just described. More specifically, referring to FIGURE 1, the case 25 may enclose either-the three-gear mechanism previously described or a Geneva cam mechanism such as is illustrated in FIGURES 46. In either event, an input shaft of the mechanism is driven by pinion 85 and chain 85A from the elliptical gear mechanism 84.

Referring now again to FIGURES 4-6, the input shaft 110 is journalled within the housing 112 by

bearings

113 and 114, and at the right hand end of the shaft 110 there is provided an eccentric cam member 115 whichis shown in greater detail in FIGURE 6. Keyed to the output shaft 111 is a gear member 116 which is shown in greater detail in FIGURE 5. The output shaft, incidentally, is journalled in the housing 112 by means of

bearings

117 and 118.

The eccentric cam member 115 is provided with a circular cam surface at 119, and this surface 119 at times mates with a correspondingly curved surface 120 in gear member 116. Referring to FIGURE 5, when the member 115 is in the position shown so that

curved surface

119 and 120 are in juxtaposition, the gear member 116 is obviously not free to rotate, and it is this condition which establishes dwell of the gear member 116 and thus of the output shaft 111. However, it will be noted that the cam member 115 also supports a cam drive element 121 which is adapted to fit within the opposing side walls forming the grooves 122 which are equally spaced angularly over the surface of gear member 116. When shaft rotates to a position wherein member has its curved surface 119 at the point of disengagement with the opposing curved surface 120, cam 121 will enter an adjacent one of the slots 122 so that angular rotation of gearmember 116 is produced in response to continued rotation of input shaft 110.

Since there are six of the slots 122 disposed at equidistant intervals about the surface of gear member 116, it follows that gear member 116 dwells throughout of rotation of the input shaft 110 and is angularly advanced during the remainder of each complete revolution of input shaft 110. When input shaft 110 being driven by output sprocket 85 of the elliptical gear mechanism of FIGURE 8, gear member 116 will dwell throughout substantially more than 120 of rotation of input shaft of the elliptical gear mechanism. For example, in one specific embodiment, the

elliptical gears

136 and 142 were constructed with an eccentricity causing sprocket 85 to rotate only 120 for of rotation of input shaft 135, with this 120 rotation being disposed symmetrically to either side of the point of minimum angularvelocity of sprocket 85. When sprocket 85 is coupled to input shaft 110 of the three-gear mechanism in such a way that sprocket 85 is at its position of minimum angular velocity at the same time that input shaft 110 has roated 60 (one-half of the 120 dwell) beyond the point when dwell of gear member 116 starts, then dwell of gear member 116 will occur throughout 180 of rotation of shaft 135. This necessarily means that dwell of gear member 116 and thus also of the feed rollers will occur during 180 of the punch press cycle.

FIGURE 7 comprises a timing cycle diagram which illustrates in a simplified manner the sequence of events involved in a completecycle of operation of the punch press. The circle shown in FIGURE 7 represents a complete cycle of operation, and the top of the circle represents the punch in the topmost position, while the bottom of the circle represents the punch in its bottommost position. FIGURE 7 shows that the dwell of the feed rolls takes place throughout 180 of a complete cycle of operation, and the apparatus of FIGURES 8 and 9 is so arranged as to assure that the amount of dwell time is centered about the bottommost position of the die, i.e. the dwell time starts at about 90 prior to the time that the die reaches its bottommost position and persists for about 90 after the die begins to retract upwardly from its bottommost position.

FIGURE 7 further shows that after the dwell time has begun at time a, but prior to the time that the stripper plate contacts the material, the feed rolls are lifted at point b. Thus, it is assumed in this embodiment of the invention that one or more guide pins are used to position the material properly prior to the time that it becomes fixed in position by the stripper plate, and it is for this reason that the feed rolls release the material prior to the time that it is gripped by the stripper plate to permit accurate positioning of the strip by the guide pins. At time c, the stripper plate grips the material and from this time until time e, the material is thus held while the actual punching operation takes place. At time d, the feed rolls are again brought into contact with the material and thereafter, at time e, the material is released by the stripper plate. At time 1, the dwell of the feed roll stops, and the strip material is then moved forwardly.

As mentioned previously, the principal advantage in being able to provide increased dwell time is to reduce the cost of die maintenance. Thus, it is necessary from time to time to sharpen the punches as they become worn in use. This naturally tends to increase the verticaldistance between the tips of the punches and the tips of the alignment or registration pins on the stripper plate which effect proper registration of the strip material prior to engagement of the strip by the stripper plate. As this distance increases, a greater portion of each cycle must be devoted to dwell time because of the increase of cycle time involved from the instant that the registration pins enter the corresponding registration holes in the strip until" the punch actually-punches the material and is subsequently Withdrawn. Throughout this time, the strip must, of course, not be advanced by the feed rolls. Accordingly, apparatus which provides a large amount of dwell time makes possible a relatively large number of successive sharpenings of the punch without requiring a complete overhaul of the entire die.

It has been describedin connection with FIGURE 7 that the pressure on the feed rolls is released at appropriate tirnes'in the cycle, and that this occurs according to the'sequence of FIGURE 7, at a time prior to that when the strip material is aligned in position by the alignment pins on the stripper plate. It will be apparent from FIG- URE 1 how the release of the feed rolls may be accomplished at any time desired in the cycle of operation of the punch press by placing a protruded portion on cam element 21 so that arm 19 will be rocked crosswise, thereby rotating arm 21 counterclockwise so as to release the feed rolls.

It has previously been described also that the stripfeed mechanism of the present invention is sufiiciently accurate, in many instances, to permit accurate registration of the strip material without the use of alignment on registration pins in the stripper plate. At such times, release of the feed rolls is made to occur only after the strip material is securely held by the stripper plate, and the reason why the strip material is released by the feed rolls at that time is to permit correction of any skew conditions which may exist between the strip material and the die. It will then be apparent to one skilled in the art how a protrusion may be placed on the cam surface 21 at such a position as to effect release of the feed rolls only after the strip materials is securely held in place by pressure from the stripper plate.

Having described several embodiments of my invention of a feed drive mechanism for a punch press, it is to be understood that modifications and alterations may be made to the specific forms shown without in any manner departing from the spirit and scope of my invention.

What I claim is:

1. In combination, a punch press or the like having a die shoe and punch and means for moving said punch relative to said die shoe from a non-punching position to and through a strip material engaging and punching position and thence back to said non-punching position on each successive cycle of operation of said press, a first shaft rotating with a uniform angular velocity through a complete revolution for each said cycle of operation, a second shaft, first means of operatively coupling said second shaft to said first shaft for rotating said second shaft with a non-uniform angular velocity, second means including an input shaft and an output shaft and comprising means interconnecting said input and output shafts for producing rotation of said output shaft in response to rotation of said input shaft over a first predetermined portion of a revolution of said input shaft and for producing dwell of said output shaft for the remainder of said revolution, third means for rotating said input shaft in response to rotation of said second shaft, and fourth means responsive tosaid output shaft for advancing the strip material toward said punch.

2. The combination of claim 1 in which said first means comprises a pair of elliptical gears coupled to said first and second shafts respectively.

3. The combination of claim 2 in which the elliptical gear coupled to said second shaft is operatively connected to said input shaft of said second means in such manner that such coupled elliptical gear rotates at its minimum angular velocity during the time said output shaft dwells.

4. The combination of claim 3 in which theoperative connection to said input shaft of said elliptical gear coupled to said second shaft is such that said coupledelliptical gear rotates at its minimum angular velocity when substantially at the midpoint of its angular range of motion throughout which dwell of said output shaft occurs.

5. The combination of claim 1 in which said second means includes: an input gear rotated eccentrically about a fixed axis in response to rotation of said second shaft, an output gear rotating about said second shaft which is fixed, an idler gear rotating about a moveable third axis, means for maintaining said idler gear in mesh with both said input and output gears, said input gear being so operatively connected to said second shaft that dwell of said output gear occurs throughout that portion of each cycle of operation of said press wherein the punch is in a position to engage the strip material.

6. The combination of claim 5 in which the fixed axis about which said input gear rotates in said input shaft of said second means.

7. The combination of claim 6 in which said input shaft A, the point of tangency B of said input gear with said idler gear, and the point of tangency C of said output gear with said idler gear all lie on the same straight line and simultaneously the angle DAB forms a right angle at some rotational position of said input gear to thereby produce dwell of said output gear.

8. The combination of claim 7 in which said first means comprises a pair of elliptical gears coupled to said first and second shafts respectively, said third means comprising coupling means so arranged that distance from the point of tangency of said elliptical gears to said second shaft is a maximum at the time that points A, B and C lie on the same straight line and angle DAB forms a right angle.

9. The combination of claim 1 in which said second means comprises a Geneva cam mechanism having a cam drive element rotatable eccentrically relative to said input shaft and a cam follower member rotatable with said output shaft, said cam follower rotating through a predetermined angle in response to rotation of said input shaft through a corresponding part of a revolution and being motionless through the remainder of the full revolution of said input shaft.

References Cited UNITED STATES PATENTS 2,858,719 11/1958 Hautau 74-84 2,861,635 11/1958 Orr 74-393 X 3,261,217 7/1966 Schick 74- -84 ANDREW R. JUHASZ, Primary Examiner.

Claims

1. IN COMBINATION, A PUNCH PRESS OR THE LIKE HAVING A DIE SHOE AND PUNCH AND MEANS FOR MOVING SAID PUNCH RELATIVE TO SAID DIE SHOE FROM A NON-PUNCHING POSITION TO AND THROUGH A STRIP MATERIAL ENGAGING AND PUNCHING POSITION AND THENCE BACK TO SAID NON-PUSHING POSITION ON EACH SUCCESSIVE CYCLE OF OPERATION OF SAID PRESS, A FIRST SHAFT ROTATING WITH A UNIFORM ANGULAR VELOCITY THROUGH A COMPLETE REVOLUTION FOR EACH SAID CYCLE OF OPERATION, A SECOND SHAFT, FIRST MEANS OF OPERATIVELY COUPLING SAID SECOND SHAFT TO SAID FIRST SHAFT FOR ROTATING SAID SECOND SHAFT WITH NON-UNIFORM ANGULAR VELOCITY, SECOND MEANS INCLUDING AN INPUT SHAFT AND AN OUTPUT SHAFT AND COMPRISING MEANS INTERCONNECTING SAID INPUT AND OUTPUT SHAFTS FOR PRODUCING ROTATION OF SAID OUTPUT SHAFT IN RESPONSE TO ROTATION OF SAID INPUT SHAFT OVER A FIRST PREDETERMINED PORTION OF A REVOLUTION OF SAID INPUT SHAFT AND FOR PRODUCING DWELL OF SAID OUTPUT SHAFT FOR THE REMAINDER OF SAID REVOLUTION, THIRD MEANS FOR ROTATING SAID INPUT SHAFT IN RESPONSE TO ROTATION OF SAID SECOND SHAFT, AND FOURTH MEANS RESPONSIVE TO SAID OUTPUT SHAFT FOR ADVANCING THE STRIP MATERIAL TOWARD SAID PUNCH.