US3505890A

US3505890A - Multi-pawl ratchet indexer

Info

Publication number: US3505890A
Application number: US777221A
Authority: US
Inventors: Carl G Peterson
Original assignee: CARL G PETERSON CO Inc
Current assignee: CARL G PETERSON CO Inc
Priority date: 1968-11-20
Filing date: 1968-11-20
Publication date: 1970-04-14
Anticipated expiration: 1987-04-14
Also published as: DE1958121A1; GB1227689A

Description

April 1970 c. G. PETERSON 3,505,890

MULTI-PAWL RATCHET INDEXER Filed Nov. 20, 1968 v 2 Sheets-Sheet 1 40 INVENTOR CARL e. PETERSON ATTORNEYS v April 14, 1970 C. G. PETERSON MULTI-PAWL RATCHET INDEXER 2 Sheets-Sheet 2 Filed Nov. 20, 1968 INVENTOR CARL G. PETERSON ATTORNEYS United States Patent O 3,505,890 MULTI-PAWL RATCHET INDEXER Carl G. Peterson, Esmond, R.I., assignor to Carl G. Peterson Co., Smithfield, R.I., a corporation of Rhode Island Filed Nov. 20, 1968, Ser. No. 777,221 Int. Cl. F16h 27/02 U.S. Cl. 74142 Claims ABSTRACT OF THE DISCLOSURE A multi-pawl ratchet indexer for close tolerance feeding on any type of roll feed, comprising a ratchet wheel fixed to a shaft, a plurality of pawls extending around the periphery of the ratchet wheel, said pawls being arranged with respect to said ratchet teeth so that there is always at least one pawl in alignment with the driving edge of said teeth, said pawls being pivotally mounted between a pair of spaced plates with means for imparting oscillatory movement to said plates, whereby to intermittently drive said ratchet wheel with a minimum of backlash, and means normally urging said pawls into engagement with said ratchet wheel, said means also functioning to limit the outward movement of the pawls at a point where the pawls barely clear the ratchet wheel.

BACKGROUND OF THE INVENTION This invention relates to feed mechanisms for stamping presses and the like, as well as other apparatus using a roll feed, and comprises an improvement over US. Patent No. 2,591,993, dated Apr. 8, 1952.

In the aforesaid patent, a ratchet wheel is provided for intermittently driving a feed shaft, said ratchet wheel co operating with a series of pawls extending in a circular path around the peripheray of the ratchet wheel, said pawls having a vernier arrangement with respect to said teeth wherein a minimum of slippage of backlash exists. It has been found desirable, however, particularly in highspeed operations, to provide positive stop means for limiting the outward movement of the pawls, and particularly to limit said outward movement to a point where the pawl just barely clears the teeth of the ratchet wheel. The failure to include such means in the aforesaid patented structure has rendered such structure unsatisfactory for high-speed applications and has further resulted in excessive wear on the spring means that normally urge the pawls toward the ratchet teeth.

SUMMARY OF THE INVENTION It is therefore a primary object of the instant invention to provide stop means for limiting the outward movement of the pawls in an indexer of the type shown in the aforesaid U.S. Patent No. 2,591,993.

It is a further object of this invention to provide means that simultaneously function as a limit stop for outward movement of the pawls and as a part of the means that normally urge the pawls inwardly toward the ratchet teeth.

Another object is the provision of a multi-pawl ratchet indexer that is capable of operating at much higher speeds than prior art indexers of this type.

Other objects, features and advantages of the invention will become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

DESCRIPTION OF THE DRAWINGS In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:

FIG. 1 is a side elevational view of an indexer embodying the instant invention with the major portion of the front face plate removed for purposes of illustration;

3,505,890 Patented Apr. 14, 1970 FIG. 2 is an end elevational view thereof;

FIGURE 3 is an enlarged fragmentary view showing the pawls and ratchet wheel;

FIG. 4 is an enlarged perspective detail of one of the pawls;

FIG. 5 is an enlarged perspective detail of the stop pin;

FIG. 6 is an enlarged exploded perspective view of the hub and ratchet wheel assembly;

FIG. 7 is a sectional view taken on line 77 of FIG. 3;

FIG. 8 is a sectional view taken on line 88 of FIG. 1;

FIG. 9 is a sectional view illustrating a slightly modified form of my invention; and

FIG. 10 is a perspective detail of one of the collar members embodied in the modified form of my invention.

DESCRIPTION OF THE INVENTION Referring now to the drawings, there is shown generally at 10 an indexing mechanism for achieving extremely accurate intermittent feed of stock from a feed roll of a stamping press, punch press or the like. It is extremely important in the feed of such stock that the feed be highly accurate and to a close tolerance, thus minimizing stock waste. The mechanism 10 comprises a pair of

identical face plates

12, 14 constructed of any suitable structural material, said plates being substantially circular and having aligned

extensions

16, 18 receiving a cross rod 20 on which a standard lever arm 22 from the stamping press eccentric (not shown) is pivotally mounted, whereby reciprocal movement of the arm 22, in response to rotation of the eccentric, results in oscillating movement of the

plates

12, 14 as a unit.

The

face plates

12, 14 rotatably receive a shaft or hub 24, said shaft being maintained in assembled relation with the face plates by means of a fixed collar 26 and a retaining ring 28, note FIG. 6. Keyed to the shaft 24, as by spline 30 and key 32, is a ratchet wheel 34 having a plurality of ratchet teeth 36 extending around its outer periphery. As previously stated, the shaft or hub 24 is rotatably mounted with respect to face

plates

12, 14, but is drivingly engaged to the feed roll shaft shown in broken lines at 38 in FIG. 2. Thus, when ratchet wheel 36 is driven by the pawl means hereinafter to be described, shaft or hub 24 turns therewith and simultaneously drives the feed roll shaft 38 to effect the desired feed of stock to the stamping press, punch press or similar equipment.

As will be seen most clearly in FIGS. 1 and 3, a series of pawls 40 is pivotally mounted on cross studs 42, said cross studs being fixedly received in oppositely disposed bores in

face plates

12, 14, as shown most clearly in FIG. 8. The series of pawls extends circumferentially around the periphery of ratchet wheel 34 and has a ver nier arrangement with respect thereto, whereby one pawl in the series will always be in substantial alignment with the driving edge of a ratchet tooth. Thus, backlash is minimized, to the extent that a feed is provided that is accurate to better than of an inch. Although the invention is operable with one series of pawls extending around ratchet wheel 34, greater accuracy can be obtained by having more than one side-by-side series of pawls, as illustrated in FIGS. 7 and 8. More specifically, when two side-by-side series of pawls are used, each pair of side-by-side pawls may have their driving edge 44 slightly offset with respect to each other, thus reducing by one-half any backlash that may occur. Expressed differently, by having the two side-by-side series of pawls slightly offset with respect to each other, a vernier arrangement is provided that would be the equivalent of having a single series of pawls but with twice the number of individual pawls. If desired, the two series of pawls may be in complete alignment with each other, as shown in FIG. 8, thus increasing the strength of the drive, al though not the accuracy thereof.

The operation and structure of the indexing mechanism 10, as described to this point, is identical to that of aforesaid US. Patent No. 2,591,993. It has been found desirable, however, to provide novel means for limiting outward pivotal movement of the pawls 40, since by carefully controlling the movement of the pawls, a much greater feed speed can be effectively obtained. The desired stop means is achieved by utilizing cross pins 46, preferably of nylon, although other suitable materials could be used, there being a pin 46 located above each pawl 40 adjacent to stud 42, but slightly ofi'set therefrom so that the pin 46 may impart a moment to the pawl or pawls with which it is in engagement. The pins 46 are received in aligned bores 48 located on the inner surfaces of

plates

12 and 14, and it is important to note that the diameter of the bores 48 is substantially larger than the diameter of pins 46, whereupon the pins are free to move radially with respect to the center of ratchet wheel 34 within predetermined limits. By the same token, the bores 48 are dimensioned so that some degree of lateral or side-by-side play exists between the pins 46 and the

plates

12 and 14. Each pin 46 is provided with a pair of circumferential grooves 50 which are adapted to receive therein a pair of springs 52, each of which extends in a complete loop around the entire circular series of pins 46, It will therefore be obvious that the springs 52 bias the pins 46 radially inwardly; and since the pins are in engaement with the pawls 40, the latter are also normally biased inwardly toward ratchet teeth 36. The relative diametrical dimensions of bore 48 and pins 46 is such that the pins 46, under action of the springs 52, are free to force the pawls radially inward to the complete depth of the ratchet teeth. The outward movement of the pawls is limited to a point where the tooth 34 of the pawl barely clears the outer edge of the ratchet teeth 36. Actually, the preferred clearance is about of an inch.

It will be understood that where only one series of pawls 40 is employed, then the pin 46 would necessarily have only one groove 50 and only one spring 52. Where two series of side-by-side pawls exist, the pins 46 have two grooves 50 and two springs 52, as illustrated. Where two series of pawls exist and the side-by-side pawls of each series are offset with respect to each other, it has been found desirable to gently curve the upper surface of each pawl 40 as shown at 54 in FIGS. 4 and 7. This curvature facilitates tilting of pin 46 when one pawl is in its down position and the pawl alongside it is in its up position, as illustrated in FIG. 7. Of course, this curvature is not necessary where only one series of pawls is employed, or where side-by-side pawls are in complete phase with each other, as illustrated in FIG. 8.

The fact that the pins 46 may move laterally is important for two reasons. First of all, this lateral play distributes the wear on the pins, and, at the same time, this play is necessary to enable the pin to tilt when one pawl is down and the pawl alongside it is up, as illustrated in FIG. 7. It will also be noted that some degree of rotation of the pins 46 will take place during operation of the device, due to vibration and the like. This rotation causes the springs 52 to move axially, thereby distributing the wear on the springs and hence increasing the working life of the springs.

In FIGS. 9 and 10, a slightly modified form of my invention is shown wherein a pin 56 is fixedly mounted between

plates

12 and 14 in lieu of the loosely mounted pin 46. The desired radial movement is achieved by mounting circular collars 58 on the pin 56, with the inner diameter of the collars 58 being substantially larger than the outer diameter of pin 56. Thus, the radial play which exists between collars 58 and pin 56 corresponds to the aforedescribed radial movement of the pins 46 in the bores 48. The collars 58 are provided with a circumferential groove 60 for receiving the springs 52 in the same manner as the aforedescribed grooves 50. In order to maintain the collars 58 properly positioned on pin 56, an

enlarged portion 62 is provided at the center of pin 56, it being understood that said enlarged portion may take the form of a washer secured to the pin or an integral flange provided thereon. Here again, it will be understood that if only one series of pawls is employed, then only one collar 58 would be mounted on pin 56, and means would be provided for properly positioning the single collar 58 so as to maintain it in alignment with the pawls.

It will now be seen that pursuant to driving movement of the arm 22, which would be movement to the left when viewing FIG. 1, the ratchet wheel 34 will be drivingly engaged by one of the pawls 40, said driving engagement taking place with a minimum of slippage and backlash, due to the fact that the vernier arrangement of the pawls with respect to the ratchet wheel insures virtually instant engagement of the ratchet wheel, no matter what the relative position is between the face plates and the ratchet wheel. The pins 46 and their cooperating springs 52 always bias the pawls inwardly, and the pins 46 simultaneously serve as limit stops for controlling the outward movement of the pawls, to a point where the teeth of the pawls barely clear the ratchet teeth, thus enabling the feed to operate much faster than has heretofore been possible. Also, by utilizing the pins 46 simultaneously as the biasing means and the stop means for the pawls, a space saving is effected which enables the indexing mechanism to have maximum compactness.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

What is claimed is:

1. In a multi-pawl ratchet indexer having a pair of spaced parallel plates, means imparting oscillating movement to said plates as a unit, a shaft extending between said plates and freely rotatable with respect thereto, a wheel keyed to said shaft having a plurality of ratchet teeth extending around its periphery, a series of pawls pivotally mounted between said plates, said pawls being positioned radially outward from the periphery of said ratchet 'wheel and extending therearound, the improvement comprising means mounted radially outward of each pawl and in engagement therewith, said means being radially movable between a first position wherein rotation of the pawl away from the ratchet teeth is limited to a point where the pawl clears the ratchet teeth but is closely adjacent thereto and a second position wherein the pawl rotates to engage the ratchet teeth for the complete depth of the latter, and resilient means normally biasing said movable means and hence said pawls to said second position.

2. In the indexer of claim 1, said movable means comprising a pin extending across said plates, recesses in said plates receiving the opposite ends of said pin, said recesses being dismensioned to permit movement of said pins between said first and second positions.

3. In the indexer of claim 2, said resilient means comprising a spring extending in a complete loop around said pins.

4. In the indexer of claim 3, each of said pins having a groove extending therearound for receiving said spring.

5. In the indexer of claim 2, said pins ebing laterally movable between said plates.

6. The indexer of claim 1 further characterized in that two side-by-side series of pawls extend around the periphcry of said ratchet wheel, said movable means comprising a pin extending across said plates, recesses in said plates receiving the opposite ends of said pin, said recesses being dimensioned to permit movement of said pins between said first and second position, said resilient means comprising a pair of side-by-side springs, each extending in a complete loop around said pins with each spring in substantial alignment with one series of pawls, the outer surface of said pawls that is engaged by said pins'being gently curved from side to side.

7. In the indexer of claim 1, said movable means comprising a fixed cylindrical pin extending across said plates, and a circular collar mounted on said pin, the inner diameter of said collar being substantially larger than the outer diameter of said pin, whereby said collar is free to move between said first and second positions.

8. In the indexer of claim 7, said resilient means comprising a spring extending in a complete loop around said collars, said collars having means on their outer surface receiving said spring.

9 The indexer of claim 1 further characterized in that two side-by-side series of pawls extend around the periphery of said ratchet wheel, said movable means comprising a fixed cylindrical pin extending across said plates, a pair of circular collars mounted on each pin, the inner diameter of said collars being substantially larger than the outer diameter of said pin, whereby said collars are free to move between said first and second positions, and means for maintaining one series of collars in substantial alignment with one series of pawls, and the other series of collars in substantial alignment with the other series of pawls.

10. In the indexer of claim 9, said resilient means comprising a pair of side-by-side springs, one extending in a 7 complete loop around one series of collars, and the other 1,418,068 5/1922 Collins 74577 1,948,082 2/1934 Strangeland 74577 2,061,000 11/1936 Michel et a1 74142 3,086,405 4/1963 Fleming 74-142 3,301,089 1/1967 Wechsler 74568 FRED C. MATTE'RN, JR., Primary Examiner W. S. RATLIFF, JR., Assistant Examiner US. Cl. X.R. 74--577