US3094576A

US3094576A - Spring quenching machine

Info

Publication number: US3094576A
Application number: US777955A
Authority: US
Inventors: Gogan Joseph
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-12-03
Filing date: 1958-12-03
Publication date: 1963-06-18
Anticipated expiration: 1980-06-18

Description

June 18, 1963 J. GOGAN SPRING QUENCHING MACHINE 9 Sheets-Sheet 1 Filed Dec. 5, 1958 IN V EN TOR. JrksEP/I 606A N ATTORNE Y5 June 18, 1963 J. GOGAN 3,094,576

SPRING QUENCHING MACHINE Filed Dec. 5, 1958 9 SheetwSheet 2 June 18, 1963 J. GOGAN SPRING QUENCHING MACHINE 9 Sheets$heet 4 Filed Dec. 3, 1958 INVENTOR. JbseP/I Gacsmv BY m KW Arman/5Y5 June 18, 1963 J. GOGAN SPRING QUENCHING MACHINE 9 Sheets-Sheet Filed Dc. a, 1958 June 18, 1963 J. GOGAN SPRING QUENCHING MACHINE 9 Sheets-Sheet 6 Filed Dec. 3, 1958 INVENTOR. Jaswl Goa/w A rroerveys June 18, 1963 J. GOGAN SPRING QUENCHING MACHINE 9 Sheets-Sheet 8 Filed Dec. 5, 1958 n whluu INVENTOR. sap/v Goa/w W4 ArmeA/E ys J0 BY 9 SheetsSheet 9 Filed Dec. 3, 1958 R NV mun mm W wh m m ww h mw 3 I N mm n rld ww nlm. m \m.

INVENTOR. Jam Goa/w United States Patent Ofitice 3,094,576 Patented June 18, 1963 3,994,576 SPRING QUENCHING MACHINE Joseph Gogan, Wisner Road, RD. 2, Willoughby, 'Ohio Filed Dec. 3,1958, Ser. No. 777,955 1 Claim. (Cl. 266-6) The present invention relates to quenching machines and more particularly to machines for conforming springs to their intended size and configuration and for quenching them while so conformed.

A primary object of the invention is the provision of animproved quenching machine for the quantlty productionof springs which will be uniform in size and shape and in quality of temper, the machine having a plurality of spring conforming or dieing stations spaced about a rotatable turret which carries the conforming stat ons sequentially through a tank or reservoir of quenching medium for simultaneous sizing or conforming and quenching of the springs carried therein.

Another object is the provision of a novel spring quenching and conforming machine in which the conforming stations comprise adjustable and cooperating sizing, shaping or straightening die means mounted on fiXed and movable die plates carried by the turret which is supported on a frame for rotation about a horizontal axis, the movable die plates being slidable toward and away from the fixed ones along guideways formed on the turret so that the dies may open and close.

Still another object is the provision of a novel machine of the above character in which cam and lever means are provided for actuating the opening and closing of the conforming or quenching stations and their dies upon rotation of the turret in a predetermined relationship to the passing of loading and discharging stations or locations in a step-by-step or intermittent manner, thereby permitting the sequential loading, conforming and quenching, and discharging of the springs.

As another object this invention aims to provide a rugged yet simple quenching machine which, by reason of the adjustable die means at each of the work stations, assumes a more versatile nature in its ability to accommodate springs of a variety of shapes and sizes and in which the adjustability of the die means is achieved through the use of movable brackets having screw adjustment intermediate various selected positions, and having cooperating teeth which may be clamped against dislodgment from their adjusted positions.

A further object of this invention includes the provision of a quenching machine in which the tank or reservoir, containing a quenching medium or oil in which the springs are immersed, has a means for greatly increasing the eiliectiveness of the quenching medium in the form of a circulating means comprising a conduit and a propelling means in the conduit for creating a current or flow of medium within the body of medium in the tank, the current being directed against the submerged springs as they are carried through the tank by the rotatable turret.

Additionally the invention has, as another object thereof, the provision of an auxiliary cooling tank as an extension to the main reservoir or tank, the extension being placed beneath the spring discharging station or location and having a conveyor means whereby further controlled cooling may be carried out subsequent to the initial quenching of the springs.

Other objects and advantages of this invention will become apparent from the following description, when taken in conjunction with the accompanying sheets of drawings forming a part of this specification and where- FIG. 1 is a front elevation of a quenching machine of this invention showing some parts in dottedlines;

FIG. 2 is an end elevation of the machine of FIG. 1;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 with some parts removed;

FIG. 4 is a sectional View taken .alongline 44 of FIG. 3. showing the cam and lever arrangements;

FIG. 5 is a front elevation. on an enlarged scale of a conforming station showing details of. the adjustable die means;

FIG. 6 is an end view of the structure of FIG. 5 as seen from the left;

FIG. 7 is an end View of the structure of FIG. 5 as seen from the right and with some parts removed;

FIG. 8 is a front elevation of another embodiment of the invention;

FIG. 9 is an end view of the machine of' FIG. 8 seen from the left;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 9 with some parts removed;

FIG. 11' is anelevation of a coil spring of the type the invention machine is adapted to quench; and

FIG. 12 is a perspective of a leaf spring such as may be formed when the machine is tooled. as in FIG. 8.

The quenching machine of this invention has, in accordance with the embodiment thereof illustrated in FIG. 1, a base or frame 10 which has as its principal part a reservoir or tank portion 11 for holding a coolant or quenching medium such as oil or the like. Other parts of the frame 10 include shaft supports 12 and 13 for rotatably supporting a turret 14, and various other brackets and supports which will be described later together with their related structures.

The turret 14 has a plurality of spring conforming or dieing stations spaced thereabout which are indicated at 15*, 15 15 the general arrangement thereof being best illustrated in FIG. 2, in which the operators position is facing the machine from the left. Heated coil springs are placed into open dies of the conforming stations of the turret 14, station 15 being shown in the loading position or location withrespect to the frame 10. Driving meansare provided for rotating the turret 14 in a stepby-step manner under. the control of the machine operator. In the embodiment which includes FIGS. 2 and 4, the rotation is in the direction of the arrow 16 and one step is equal to one-eighth of a complete revolution, whereby each of the dieing stations assumes the position previously occupied by its neighbor.

Thus, a spring W loaded into the open dies of station 15 will move next to the position occupied by station 15 which is immersed in the quenching oil or other suitable medium within the tank 11. A spring W so positioned will be in the path of a current of quenching medium directed by a circulating means indicated generally at 17.

As the conforming or dieing stations pass from the position 15 to 15 the quenched and sized or shaped springs W are released by the dies for removal or ejection therefrom. The release is effected as the dieing stations pass that portion of the frame designated generally as a discharge station or location 18. In some instances further controlled cooling or quenching is required and for this purpose an auxiliary or extension quenching means, indicated generally at 20 in FIG. 9, is provided.

Coming now to a more detailed description of the machine and the mechanisms of which it is constituted, the turret 14 is seen to comprise a pair of octagonal end members or frames 22' and 23 secured for support and rotation vw'th a shaft 24. The

end members

22 and 23 have flats or

guideways

25 and 26 respectively, which present supporting surfaces for fixed die plates 27 and movable die plates 28, there being one fixed and one movable die plate for each station 15.

The shaft 24 is supported for rotation about a horizontal axis in suitable bearings 30 and 31 carried by the shaft supports 12 and 13 which are fitted into the tank or reservoir 11 and are conveniently supported therein by

brackets

32 and 33. Fitted to the shaft 24, and secured thereto, is a bull gear 34 having meshing engagement with a pinion 35 forming part of the above mentioned step-'by-step or intermittent driving means.

The shaft support 12 is provided with a backing plate 36 surrounding the shaft 24 and supporting an annular boss or track 37. Shaft support 13 is, itself, provided with a backing plate portion or flange .38 and has an annular boss or track 39 formed thereon. Attached to the

backing plates

36 and 38 and the

annular tracks

37 and 39 are roller

directing cam elements

40, 41, and 42 which form a part of means for actuating the movable die plates 28 along the guideways 25 and '26 in the open-ing and closing of the dies carried thereby.

The end member 22 of the turret 14 is provided with a plurality of bearing openings 43, each of such openings being adjacent one of the die stations and being in alignment with a corresponding opening 44 in the end member 23. Journalled in the

openings

43 and 44 are connecting shafts 45 which serve to join pairs of form

plate moving levers

46 and 47 which are keyed thereto at 48 and 49 respectively, for parallel motion.

Each of the

levers

46 and 47 has a die plate moving end connected b links 50 to an ear 51 on its adjacent movable die plate 28. Likewise each of the

levers

46 and 47 is provided with cam engaging roller means 52 which are adapted to be directed or guided by the

cams

40, 41, and 42 during rotation of the turret 14.

The fixed die carrying plates 27 may be secured directly to the

flats

25, 26 of the turret 14 as by screws 53, whereas the movable die plates 28 are slidable along the flats or

guideways

25, 26 and are constrained against motion radially outwardly by retaining guides 54.

As may be seen most conveniently in FIG. 4, the

levers

46 and 47 are in the form of hell cranks, and together with their rollers 52 and links 50 they cooperate with the

cams

40, 41 and 42 to effect a movement of the movable die platesv 28 with respect to the fixed die plates 27 as the turret 14 rotates about its horizontal axis as determined by the supporting shaft 24. The motion imparted to the movable die carrying plates 28 opens and closes the dies of the conforming or dieing stations 15 in a predetermined relation to the rotation of the turret 14 with respect to the base or frame 10.

Each of the fixed plates 27 carries adjustable tools or dies 57 while each of the movable plates 28 carries adjustable tools or dies 58, the dies being somewhat diagrammatically illustrated in FIG. 4. When a dieing station is in the position of 15 its actuating levers or

bell cranks

46 and 47 will have their rollers 52 riding on the bosses or tracks 39 and about to engage the earns 41, the

dies

57 and 58 then being in their opened position and being in the loading location with respect to the frame After loading a spring or workpiece W into the open dies of the station the operator will actuate the driving means to rotate the turret 14 one step, or in this instance one-eighth of a revolution, bringing the station 15 into the position previously occupied by station 15 In approaching the position of 1'5 the rollers 52 of

levers

46 and 47 ride up, or radially outwardly of the turret, along the cam element 41, rotating the levers about the pivot provided by the connecting shaft 45 in its

bearings

43 and 44, thereby shifting the associated movable die plate 28 along the

flats

25 and 26 toward the fixed die plate 27 through the agency of the connecting links 50 and cars 51. The shifting of the plates 28 closes the dies 57' and 58 and effects a conforming of the hot workpiece or spring W to a predetermined size and shape for quenchmg.

In moving from the position of 15 to that of 15 the spring W is carried beneath the surface level 60 of the quenching medium held in the tank or reservoir 11 and into the path of a current of quenching medium indicated by the arrows 61 which is directed by the circulating means 17. The current which is generated within the body of the quenching medium increases the effectiveness thereof to a marked degree by removing the heated quenching oil from the vicinity of the spring being quenched.

The circulating means 17 embodies a conduit 62 having a vertical portion or trunk 63 which terminates at a position 63* somewhat below the surface level of the quenching medium, and a horizontal portion 64, the horizontal portion terminating in a current directing batfle 65 and a restricted opening 66. The opening 66 is advantageously positioned with respect to the turret 14 so as to direct the flow of quenching medium against the springs W which are conformed and carried by the dies 57 and 58 as the dieing stations progress from the position of 15 to that of 15'.

An electric motor 67 is supported on the frame 10 by suitable brackets 68 and is provided with an extended drive or propeller shaft 69 having a propeller 70 secured thereto. The shaft 69 and propeller 70 are arranged for rotation about a vertical axis within the vertical portion 63 of the conduit 62. Quenching medium flows into the vertical portion 63 of the conduit 62 by virtue of the submerged open end 631 and is accelerated or propelled through the conduit by the propeller 70 to emerge as a directed current or flow as described above.

The cooling springs or workpieces W remain submerged in quenching medium as they traverse the positions of the stations 15 through 15 In so doing the rollers 52 are maintained in their outward position by the cam elements 42, and hence the dies 57 and 58 are retained in their closed or spring conforming positions While traversing the tank 11 of quenching medium.

Upon reaching the position occupied by the dieing station 15 the rollers 52 of the levers or bell cranks 46 and 47 will, by virtue of the effect of gravity on the die plate 28 and dies carried thereby, leave the cam elements 42 and come under the influence of the cam elements 40. The cam elements 40 serve to direct the rollers 52 radially inwardly of the turret 14, whereby the

levers

46 and 47, acting through the links 50, draw the movable die plates 28 away from the fixed die plates 27 opening the dies 47 and 48 to release the conformed and quenched springs W.

When they are released, the springs may be removed or may be ejected by some suitable means from between the dies, and allowed to roll down a ramp or incline 70 forming a part of the discharge station 18 to an awaiting receptacle or to the previously mentioned tank or reservoir extension 71 for additional controlled cooling.

To proceed with a more particular description of the

die plates

27 and 28 and of the adjustable die means 47 and 48 carried thereby, attention is directed to the illustrations of FIGS. 5, 6 and 7 which provide a more detailed view of the arrangements involved.

A straightening die tool or bar 75 is supported for limited resilient motion by an adjustable L-shaped bracket 76, which has a mounting portion 77 and a die supporting portion 78. The mounting portion 77 is provided at either end with areas of transversely extending teeth or serrations as at 79 and 80. These toothed portions or areas 79 and 80 have elongated openings 81 and 82 therethrough and are adapted to co-operate with complementary toothed areas of clamping

elements

83 and 84. Screws 85 extend through the clamping

elements

83 and 84, through the openings 81 and 82, and into threaded engagement with the die plate 27, thereby permitting the bracket 76 to be releasably clamped in any of a number of positions of adjustment to accommodate springs W of a variety of sizes.

Extending through the bar supporting portion 78 of the bracket 76 are a pair of screws or

bolts

87 and 88 having threaded engagement with a pair of clevises or yokes 89 and 90 which are secured to the bar 75 by bolts 91 and 92. The

bolts

87 and 88 are surrounded by, and reciprocable in, bushings 93 and 94 which are secured to the bracket portion 78 as at 95, and serve to guide and to limit the movement of the bar 75. Interposed between the bracket 76 and the bar 75 are a pair of compression springs 96 which urge the straightening die or bar 75 against the hot spring W (shown in dot and dash lines in FIG. 5) to straighten or conform the spring as it is quenched in the tank 11.

The movable die plates 28 each carry two straightening dies or bars 100 and 101 supported thereon by adjustable bracket means having a die supporting portion 102 and a mounting portion 103, portions 102 and 103 being maintained substantially at right angles to one another by buttresses 104. The mounting portion 103- is provided with end portions 105 and 106 having areas of transversely extending teeth or serrations and having elongated

openings

107 and 108, respectively, therethrough. The die plate 28 is provided with a plate 109 having teeth or serrations which are complementary to and cooperate with those formed on the end portions 105 and 106 of the bracket mounting portion 103. Screws 110 extend through the

slots

107 and 108 into the die plate 28 and serve to clamp the straightening dies or bars 100, 101 in any of a number of adjusted positions.

The

bars

100 and 101 are beveled as at 100 and 101 to provide a V-shaped support for hot coil springs which are pressed thereagainst by the spring mounted bar 75 so that the springs are straightened and held straight while they are quenched.

Means are provided also to size the springs W to a predetermined length, which means is operated by the closing of the dies by motion of the die plates 28 towards the fixed plates 27, and which means is conveniently adjustable to accommodate a wide range of spring lengths. For this purpose the movable die plates 28 each carry a pair of sizing or end dies in the form of disk-

like plates

115 and 116. The end plate 115 is provided with a screw threaded shaft 117 which extends through an internally threaded adjusting bushing 118. The adjusting bushing 118 is, itself, rotatably supported in a collar or ring 119 which is carried by a bracket or pedestal 120 having a base plate 121, and the bushing is provided with notches 118 for receiving a spanner or other adjusting tool.

The base plate 121 has a keyway 121 in engagement with a longitudinally extending key 122 which serves to assure proper alignment of the base plate and the end die or plate 115 supported thereby. The die plate 28 has a plurality of tapped holes 123 therealong which are adapted to receive base plate mounting screws 124. Thus the end plate 115 can be adjusted in its position by selecting the holes 123 to be used in securing the base plate.

Intermediate adjustment of the position of the end plate 115 is achieved by rotating the adjusting bushing 118 to advance or retract the threaded shaft 117. In this manner the length of spring W to be quenched may be accurately determined.

An end plate 116 is carried on each movable die plate 28 by supporting means which permits motion of the end plate 116 with respect to the end plate 115. The end plate 116 is provided with a shaft 125 which extends through, and is supported for reciprocation in, a block 126 which is secured to an L-shaped bracket means 127.

Adjacent the end plate 116 and in abutting relation therewith is a wedge 128 which is adapted to move along a slideway 129, and in unison with the end plate 116 and the shaft 125. A similar but bifurcated wedge 130 is secured to the fixed die plate 27, and is adapted to have

legs

130 and 130 straddle the shaft .125 and to be interposed between the wedge 128 and a suitable facing 126* of the block 126. A compression spring 131 surrounds the shaft between the block 126 and a shoulder 132 on the shaft, and this spring urges the end plate 116, Wedge 128 and the shaft 125 to shift away from the end plate 115 when the wedge is withdrawn by the movement of the die plate 28 away from die plate 27. Conversely, upon closing of the dies as when a spring W has been loaded therein and the die station is advanced from 15 to 15', the

wedges

128 and 130 will cooperate to shift the end plate 116 toward the end plate 115 against the bias of spring 131 and the spring W will be compressed and held for quenching at a predetermined length.

The driving means by which the turret 14 is rotated in a step-by-step manner includes a suitable motor such as at which is conveniently mounted on a reduction gearing housing 141 and which is adapted to drive a shaft 142 through a transmission means such as the chain drive 143. The ratio between the pinion 35 and the bull gear 34 is such that a single revolution of the pinion will advance the turret one-eighth of a turn, or one station in the embodiment shown.

The pinion 35 is secured for rotation with a shaft 145 as is the driven member 146 of a single revolution clutch, the drum of a brake 147, and a cam plate 144 (FIG. 1). The shaft *145 is supported for rotation in

suitable bearings

148 and 149 and has a driving member .150 of a single revolution clutch journaled thereon. A worm wheel 151 is secured to the clutch driving member and is in meshing engagement with a worm gear 152 carried by the motor driven shaft 142.

Control of the rotation of the turret is effected by the machine operator through a foot pedal 155 which is connected by a suitable linkage to a lever arm mounted on a control shaft 156. Rotation of the: shaft 156 upon depressing the foot pedal 155 lifts a latch or detent 159 from engagement with a spring loaded pin 160 allowing the latter to move under the influence of its spring and to engage the driving member or disk 150. The driving member .150 is continuously rotating and when engaged by the pin 160 carries the driven member 146 into rotation, thereby rotating the pinion 35 and the cam plate 144.

Depression of the foot pedal 155 also swings a lever arm 161 to operate a switch 162 which de-energizes the brake 147 to allow the rotation of the shaft 145. When the foot pedal 155 is released, the detent or latch 159 is moved into a slot 163 in the driven clutch member 146 and is adapted to retract the pin 160 from engagement with the driving member 150 at the completion of one revolution by the clutch as a unit. As the pin 160 is retracted a pin or projection 164 on the cam plate 144 engages or strikes a limit switch 165 which is in circuit with the brake 147 and is effective upon actuation to energize and set the brake against further rotation of the shaft 145.

Thus upon each depression and release of the control pedal 15 5, the turret 14 will rotate sufficiently to advance each dieing station to the position previously held by its neighbor and will stop with a dieing station in the open position as at 15 ready to receive a spring W.

In FIGS. 8, 9 and 10 there is illustrated a somewhat modified form of the invention which is particularly adapted to the shaping or conforming and quenching of fiat or leaf-type springs such as are shown in FIG. 12. In these figures, elements corresponding to similar elements already described, have similar reference characters.

The quenching machine illustrated in FIG. 8 has a base or frame 10 and a turret 14 having fixed die plates 27 and movable die plates 28, however the tools or dies carried thereby are somewhat different than those previously described. The tools used include a form 170 on each of the movable die plates 28, having die elements 171 spaced therealong, and having a curvature representing the curvature or camber desired in a completed or quenched spring leaf 172 such as is illustrated in FIG. 12. Mounted on the fixed or stationary die plates 27 are spring mounted presser pads or dies 172 which cooperate with the dies 171 to bend the leaf spring blank or strip S into a curve or camber for quenching. In this embodiment, the details of which are more clearly seen in FIG. 10, the bell cranks or levers 46- and 47 are provided with bifurcated or slotted ends '176 and 177 which have a sliding connection with the

pins

178 and 179 presented by

guide brackets

180 and 181, the latter retaining the movable die plates 2-8 in sliding relation with the

surfaces

25 and 26 of the turret.

The operation of the machine when tooled for flat springs is the same as has, been described with regard to coil springs but for convenience a slightly diiferent arrangement of the driving motor 140, with respect to the reduction gear housing 141, has been illustrated. Also, it may be found advantageous in either arrangement to control the machine through the use of an electricfoot switch 183 in circuit with suitable solenoid operated valves for actuating a pneumatic motor or air cylinder 184, connected to the clutch control shaft 156. The auxiliary or extension cooling means 20 may be embodied in either form of the machine of this invention and comprises a tank 186 for holding a quenching liquid or medium, and a suitable conveyor having a traveling carrier means or belt 187, sprockets or drums 188, and guide means 189. As the springs are discharged during passage of the dies from the position of 15 to that of 115 adjacent the discharge station 18, they are permitted to drop into the extension tank 186 and onto the conveyor 187 by which they are carried at a predetermined rate for the desired additional cooling.

The use of the quenching medium circulating means 17 together with the auxiliary cooling means provides a machine for quenching springs which has a high pro duction capacity and is very flexible in that it can effect a controlled rate of cooling for springs having a wide range of tempers.

A number of pipe connections 190 are shown which communicate with the interior 'of the tank 1 1, and which are used for the supply-or draining off of the quenching medium and for connection with heat exchangers if the rate of production requires additional cooling of the quenching medium.

From the foregoing description of the invention it will be apparent that there has-been provided an improved spring quenching machine which, by reason of its novel design, adaptable die means, and practical circulating means for the efficient use of the quenching medium, will permit a more rapid and economical production of coil and leaf springs than has been attainable heretofore.

Although the machine of this invention has been described with reference to several definite arrangements thereof and in a somewhat detailed manner, it is understood that the invention is not to be limited to those particular embodiments described, but rather that the invention includes all those changes, substitutions and modifications as come within the scope of the appended claim.

Having thus described my invention, what I claim is:

A quenching machine comprising; a support means including a tank having side Walls and adapted to contain quenching'liquid; bearing brackets attached to said side walls and supporting substantially horizontally 0 aligned bearings; a main shaft rotatable in said bearings; polygonal-shaped end members spaced apart axially of said main shaft and mounted thereon for rotation therewith and having substantially straight peripheral portions at the locations of the sides of the polygonal shape; an annular series of workholder devices mounted on said end members at the locations of said straight portions and adapted to receive and hold workpieces to be quenched; said workholder devices each comprising a fixed workholder member secured against an axially op posed pair of said straight portions, and a co-operating movable workholder member slidably supported by said pair of straight portions and having opening and closing movement relative to said fixed workholder member; unidirectionally rotatable drive means connected with said main shaft to rotate the same for moving said work holder devices with the workpieces therein through said quenching liquid in succession; bosses on said bearing brackets and projecting toward each other in a coaxial relation to said main shaft and having cylindrical periph eral surfaces extending therearound; said end members having hub portions secured on said main shaft at points immediately adjacent said bosses and provided with circumferentially spaced axially aligned bearing openings whose centers lie on circles of larger diameter than said bosses; an annular group of rockshafts disposed around said main shaft in a parallel relation thereto and rockable in said bearing openings; said rockshafts having end portions projecting from said end members on the remote sides of the latter; actuating members of bell crank shape secured on said end portions of the rockshafts and having angularly disposed first and second lever arms; means connecting said first lever arms said movable Workholder members for imparting the opening and closing movement thereto; stationary cam means supported by said bearing brackets comprising a pair of workholderopening first cam segments extending part way around said bosses on the upper side thereof, and a pair of workholder-closing second cam segments extending part way around said bosses on the lower side thereof; said first cam segments having first thrust surfaces facing toward and spaced from portions of said peripheral surfaces, and said second cam segments being seated against other portions of said peripheral surfaces and having second thrust surfaces facing away from said other portions; said first and second cam segments being disposed with adjacent end portions on at least one end thereof in a circumferentially contiguous relation; and roller means carried by said second lever arms and co-operable with said cam means in response to rotation of the workholder devices by said main shaft; said roller means comprising first rollers engageable with and rollable along said first thrust surfaces for causing swinging of said actuating members in a direction to produce opening of the workholder means, and second rollers engageable with and rollable along said second thrust surfaces for causing said actuating members to produce and maintain a closed condition of said workholder means.

References Cited in the file of this patent UNITED STATES PATENTS 908,440 Baldwin Jan. 5, 1909 976,891 Machllet Nov. 29, 1910 1,249,473 Peck Dec. 11, 1917 1,487,530 Bowers Mar. 18, 1924 1,595,803 Merter Aug. 10, 1926 2,638,909 Hiatt May 19, 1953