US3596301A

US3596301A - Pointer

Info

Publication number: US3596301A
Application number: US781092A
Authority: US
Inventors: Allan D Haines
Original assignee: National Machinery Co
Current assignee: National Machinery Co
Priority date: 1968-12-04
Filing date: 1968-12-04
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03
Also published as: DE1960907A1; DE1960907C3; DE1960907B2

Abstract

A high-speed pointer for bolts, screws, and the like is disclosed which includes a gripper chuck operable to carry blanks into cutting engagement with a rotating cutter. The chuck includes power-operated gripper means to grip the blank and power means provided to reciprocate the chuck toward and away from the cutter. The chuck is urged toward the cutter by a drive spring sized to feed the blank into cutters without ''''chatter.'''' The gripper means are provided with springs which actuate the grippers and also function to urge the chuck toward the cutter when the grippers are released. Therefore, the gripper-actuating springs also function to assist in both accelerating starting down movement and decelerating arriving up movement of the chuck.

Description

United States Patent 3,146,471 9/1964 Edmondson. 10/21 FOREIGN PATENTS 388,069 5/1965 Switzerland lO/2l 959,269 5/1964 Great Britain 10/9 Primary Examiner-Charles W. Lanham Assistant ExaminerE. M. Combs A!!0rne \'--MCNenny, Farrington, Pearne & Gordon ABSTRACT: A high-speed pointer for bolts, screws, and the like is disclosed which includes a gripper chuck operable to carry blanks into cutting engagement with a rotating cutter. The chuck includes power-operated gripper means to grip the blank and power means provided to reciprocate the chuck toward and away from the cutter. The chuck is urged toward the cutter by a drive spring sized to feed the blank into cutters without chatter. The gripper means are provided with springs which actuate the grippers and also function to urge the chuck toward the cutter when the grippers are released. Therefore, the gripper-actuating springs also function to assist in both accelerating starting down movement and decelerating arriving up movement of the chuck.

PATENTEDAus 3|97l 3,596,301

sum 1 0F 3 IN VEN 7' 0)? PATENTED AUG 3 I971 SHEET 3 [1F 3 POINTER BACKGROUND OF INVENTION PRIOR ART In the U.S. Pat. to Edmondson No. 3, l46,47l dated Sept. 1, 1964, a pointer mechanism is disclosed which includes a reciprocating chuck arranged to grip a headed blank and carry such blank into engagement with a cutter arranged to form a point on the blank. Edmondsons machine operates to radially grip the shank of the blank immediately below its head and to axially grip the head so that the blank is positively located in both a radial and an axial direction. The two gripping mechanisms operate in response to movement of the gripping slide from its blank receiving and discharge position toward the cutting position.

SUMMARY OF INVENTION A pointer incorporating the present invention is similar in certain respects to the pointer disclosed in the Edmondson patent described above. For example, the present pointer includes a gripper slide reciprocable toward and away from a rotating cutter. The slide is provided with gripping means which radially grip the shank and axially grip the head to provide precise positioning of the blank. The present pointer, however, is capable of higher operating speeds and is simpler in certain respects.

A pointer incorporating the present invention utilizes spring means to urge the reciprocating slide in the direction toward the' cutting position. The power drive for reciprocating the slide includes a cam operated linkage wherein the principal.

operating links are placed in tension. This arrangement provides a twofold advantage. First, separate overload relief means are not required to protect the mechanism in the event of jamming or the like and the use of a drive linkage wherein the principal links are placed in tension rather than in compression permits the use of smaller lightweight connecting elements.

In addition, a pointer incorporating the present invention utilizes power operated means to control the operation of a gripper mechanism. This permits a reduction of the chuck stroke and permits the mechanism to properly operate at higher speeds. The reduction in the necessary stroke of the slide permits higher operating speeds by reducing the acceleration forces involved and in addition pennits the pointer to function with a cycle wherein a greater portion of the cycle is used to perform the actual cutting operation on the blank. Consequently the pointer can be operated at a higher cyclic speed without excessively reducing the time provided for the actual cutting operation.

In the illustrated embodiment a drive spring is provided to resiliently urge the slide toward the cutter. In addition a spring is associated with each of the grippers. The gripper springs operate to resiliently urge each of the gripper linkages toward their operated gripping position. The structure is arranged so that the gripping force is not affected by chuck movement.

A separate powered gripper operator is provided to release the grippers as the chuck approaches its blank receiving and discharge position and to maintain the grippers in the release condition until after the chuck commences to move toward the cutting position. The structure is arranged so that the gripper springs urge the chuck toward the cutting position whenever the grippers are released. Therefore, the gripper springs assist the drive spring in accelerating the chuck toward the cutting position and in decelerating the chuck as it returns to the receiving and discharge position. With this structure the chuck can be accelerated and decelerated very rapidly so higher cyclic speeds can be obtained. After the initial acceleration of the slide, the slide is urged toward the cutter only by the force of the drive spring. Consequently the gripper springs function initially to assist in accelerating the slide toward the cutter but do not function in this manner during the actual cutting operation.

DESCRIPTION OF THE DRAWINGS FIG. Us a side-elevation of a combined machine, including a pointer incorporating this invention, wherein the combined machine is adapted to,form threaded articles, such as bolts,

screws, and the like from rod or wire stock;

FIG. 2 is an enlarged fragmentary side elevation, partially in section, illustrating the blank supporting slide and the gripper mechanism; v

FIG. 3 is a broken section taken generally along 3-3 of FIG. 2 illustrating the. power means which operate the gripping mechanism and reciprocate the slide; and,

FIG. 4 is a fragmentary perspective view illustrating the upper ends of the power mechanism for operating the pointer.

Referring to FIG. 1, the illustrated machine includes a progressive header operable to shear blanks from rod or wire stock and progressively upset the blanks to form a bolt'blank or the like having a head and a shank. It should beunderstood, however, that a pointer incorporating this invention may also be used by itself or in combination with other types of machines such as a double-blow header. The header includes a frame 10 in which a slide (not illustrated) is reciprocable toward and away from a die breast. Cooperating tools and dies carried by the slide and die breast operate to sequentially form a bolt blank. A transfer indicated generally at 11 operates to progressively transfer the blanks to each of the die stations. A stockfeed mechanism 12 operates to feed rod or wire stock 13 into the machine where it is sheared into blanks and formed into blanks.

The blanks are transferred from the header to a pointer 14 incorporating this invention by tube or track means (not illustrated) of a type illustrated in the Edmondson patent cited above. From the pointer the blanks are transferred to a roll thread mechanism 16 which rolls threads onto the shank of the blank. The various systems and subassemblies are powered in timed relation. In the illustrated machine a fly wheel 17 is mounted on the main crank shaft which powers the header slide and also the thread roller 16. An accessory drive shaft I9 is driven by a gear connection at the same speed as the main crankshaft. The power drive for the pointer 14 includes cams mounted on the accessory drive shaft 19 so the pointer 14 is operated in timed relationship with the overall machine. Reference may be made to the copending applications Ser. No. 780,153, filed Nov. 29, 1968, now U.S. Pat. No. 3,555,586 and Serial No. 784,806, filed Dec. 18, 1968 for a more detailed description of the machine illustrated in FIG. 1.

The pointer mechanism I4 includes two basic assemblies; the upper chuck assembly 21 and the lower cutter spindle and drive assembly 22. The chuck assembly is operable to receive individual blanks, to accurately locate and tightly grip the blanks, and to carry the blanks down against cutter within the cutter assembly to form an accurately dimensioned point on the end of the blank:

Referring to FIGS. 2 through 4, the chuck assembly 21 is driven by a chuck drive linkage 23 and a gripper drive linkage 24 each of which is powered by-an associated

cam

26 and 27 respectively. These cams are mounted on the accessory drive shaft 19. Therefore, the operation of the chuck assembly is timed with the operation of the basic heading machine and the pointer has an output at least equal to the output of the heading machine.

The chuck assembly structure includes a frame 28 mounted on the frame 10 of the heading machine and a reciprocating chuck 29 mounted on the frame 28 for vertical reciprocation relative thereto. The chuck 29 is formed with guideways 31 which engage rollers 32 journaled on the frame 28. The rollers 32 are preferably provided with adjusting means to permit preloaded engagement with the guideways. Such preloading of the rollers insures that the chuck is locked against any lateral play and eliminates clearance necessary in the usual slide type of bearing guides. The complete elimination of lateral clearance enables high-speed pointing operations since it eliminates one of the major causes of chattering during such cutting operations.

In order to grip the blank 33 within the chuck 29, two separate gripping devices are utilized. The first operates to grip the head and axially position the blank relative to the chuck and the other operates to grip the shank to laterally position the blank relative to the chuck. The head gripping mechanism includes an insert 34 mounted in the chuck 29 and formed with a head receiving recess. The bottom wall of the recess is formed by a laterally extending flange 36 against which the bottom of the head 37 of the blank 33 is positioned. The inner end of the flange 36 also provides a face against which the shank 38 of the blank 33 is clamped or gripped. A gripping or clamping rod 39 extends through a bore in the insert 34 and is proportioned to engage the upper side of the head 37 and firmly press the head against the flange 36 to axially locate the blank. A spring 41, illustrated in FIG. 3, acts to resiliently urge the clamping rod 39 upwardly to an unclamped position while permitting the clamping rod to move down into clamping engagement with the head 37 of the blank 33.

Lateral gripping of the blank 33 is provided by a laterally movable jaw element 42 mounted on the chuck 29. The jaw element 42 is formed with a flange 43 laterally aligned with the flange 36 of the insert 34 and having an upper wall engaging the underside of the head 37 of the blank 33. The end face of the flange 43 is formed with a V-groove which engages the shank 38 to laterally position the blank by clamping the shank against the flange 36. in this manner positive control of the blank 33 and accurate positioning of the blank within the chuck 29 is achieved when the jaw element 42 is moved into engagement with the blank and the clamping rod 39 engages the head 37 of the blank.

The linkage for controlling the clamping rod 39 includes a push rod 46 axially aligned with the clamping rod and mounted in the chuck 29 for vertical reciprocation relative thereto. A spring 47 resiliently urges the push rod 48 in an upward direction toward the ungripped position. A cam arm 48, best illustrated in FIG. 2, is pivoted on the chuck 29 for rotation about a pivot axis 49. A screw 51 is threaded into the cam arm 48 and is positioned to engage the upper face of the push rod 46 so that clockwise rotation of the cam arm 48, to the illustrated position, operates to push the push rod 46 downward and thereby moves the clamping rod 39 into engagement with the upper side of the head 37 of the blank.

The cam arm 48 is formed with a cam face 52 engageable with a center roller 53 in a yoke 54 which is mounted on the end of a rod 56. Front and back rollers 57 journaled on the yoke 54 engage the face of a guide member 58 to laterally support the yoke 54. Reference should be made to the Edmondson patent cited above for a more detailed description of this structure. The various elements are proportioned so that upward movement of the yoke 34 with respect to the chuck 29. to the position illustrated, in FIG. 2 causes engagement between the cam face 32 and center roller 33 which produces clockwise rotation of the cam arm 48 to the gripping position. Conversely downward movement of the yoke 34 from the illustrated position permits anticlockwise rotation of the cam arm 48 under the influence of the springs 41 and 47 from the illustrated position. Such action results in release of the axial gripping. Therefore, the operation of the axial gripping linkage is controlled by the vertical position of the yoke 54 with respect to the chuck 29.

A spring 59 is positioned around the rod 56 and engages the upper surface of the chuck 29 at its lower end. The upper end of the spring is seated against a thrust washer 61 which is in turn positioned with respect to the rod 56 by a shoulder 62.

The spring 59 is in compression and operates to resiliently urge the rod 56 and in turn the yoke 84 in an upward direction with respect to the chuck 29 to produce axial gripping of the blank. A rocker arm 63 which constitutes a part of the gripper-operating linkage 24 is mounted on the frame 28 for pivotal movement about a pivot axis 64. A gpller 66 is mounted on the rocker arm 63 and is positioned to engage the upper end of the rod 56 to press it down against the action of the spring 59 to release axial gripping of the blank 33.

The lateral gripping of the blank is controlled by a separate but functionally similar linkage. In this case a cam arm 67 is pivoted on the chuck 29 for movement about a pivot axis 68. An adjustment screw 69 is threaded into the lower end of the cam arm 67 and is positioned to engage the jaw 42 at a location substantially aligned with the flange 43. Clockwise rotation of the cam arm 67 to the position illustrated in FIG. 2 causes the jaw 42 to tightly grip the shank 38 of the blank 33.

The upper end of the cam arm 67 is provided with a cam face 71 proportioned to engage a center roller 72 on a yoke 73. Here again, front and back rollers 74 are journaled on the yoke 73 and engage a bearing element 76 to laterally support the yoke 73. When the yoke 73 moves upwardly to a position illustrated in FIG. 2, the cam arm 67 is rotated in a clockwise direction to the locked or gripped position illustrated. Conversely when the yoke 73 moves downwardly with respect to the chuck 29, the lateral gripping is released.

The yoke 73 is mounted on the lower end ofa rod 77 which extends up beyond the chuck 29. Here again, a spring 78 extends between the upper surface of the chuck 29 and a thrust washer 79 to provide a resilient force urging the rod 77 in the upward direction. Therefore, the spring 78 urges the elements toward a blank-gripping position. Here again, a roller 81 on the rocker arm 63 is positioned to engage the upper end of the rod 77 to overcome the action of the spring 78 and release the lateral gripping linkage when such release is required.

The linkage for operating the rocker arm' 63 is best illustrated in FIGS. 3 and 4. The linkage includes a second rocker arm 82 pivoted on frame extensions for pivotal movement about a pivot axis 83. A forward projection on the rocker arm 82 is provided with a roller 84 engaging a bearing pad 86 on a rearward extension of the rocker arm 63. An operating rod 87 is pivotally connected at 88 to the rocker arm 82 at one end and is pivotally connected at 89 to a follower arm 91 on the machine frame 11). The follower arm 91 is pivoted on the frame at 92 and is provided with a roller 93 which engages the cam 27.

A spring 98 (illustrated in FIG. 4) is connected to the rocker arm 63 to urge the rocker arm in a clockwise direction as viewed in FIGS. 3 and 4. The various elements are arranged so that engagement of the roller 93 with a lift portion of the cam 27 causes anticlockwise rotation of the follower arm 91 which pulls operating rod 87 downwardly and produces clockwise rotation of the rocker arm 82. This results in anticlockwise rotation of the rocker arm 63 and in turn causes the

rollers

66 and 81 to press downwardly on their associated

rods

36 and 77 to overcome the action of the springs 59 and 78. Consequently the rod 87 is placed in tension when it functions to release the gripping and is not subjected to column loading. Therefore, the rod 87 may be relatively small in diameter and relatively small in cross section. The spring by virtue of the connection between the two rocker arms 63 and 82 p reloads the operating rod 87 in tension and resiliently urges the follo'wer roller 93 toward engagement with the cam 27.

The reciprocation of the chuck 29 is controlled by the drive linkage 23, best illustrated in FIG. 3. This linkage includes a rocker arm 96 pivoted at on the frame 28 of the pointer and provided with a bearing pad 98 engageable with the underside of a roller 99 on the chuck 29. The opposite end of the rocker arm 96 is pivotally connected at 181 to a second operating rod 102. The lower end of the operating rod 102 is pivotally connected at 103 to a second follower arm 104. Here again the follower arm 164 is pivoted at 92 on the frame of the machine and is provided with a roller follower 106 engageable with the cam 26.

A main spring 107 extends between the frame assembly 28 and the upper side of the chuck. The spring is in compression and urges the chuck in a downward direction. The operation of the cam 26 and its associated linkages is to overcome the action of the main spring 107 and to raise chuck 29 against the action of the spring 107. Here again the operating rod 102 is placed in tension and is not subjected to column loading which would require a large rod. The use of the spring 107 to urge the chuck in a downward direction rather than a positive mechanical drive also eliminates the need for overload relief means since the downward force is limited to the force of the springs.

The cam 26 is shaped to allow downward movement of the chuck 29 until the end of the blank 33 engages a rotating cutter 111 which rotates about an axis 112 coaxial with the shank 28 of the blank 33. In operation the blank is positioned in the chuck 29 when the chuck is at an upper position spaced from the cutter. The earns 26 and 27 are preferably shaped so that the

rollers

66 and 81 maintain engagement with the associated

rods

56 and 71 as the chuck commences its downward movement toward the cutter. When such timing is provided, all of the

springs

59, 78, and 107 provide a force acting on the upper side of the chuck 29 so that the chuck can accelerate rapidly. The cam 27 is shaped so that the

rollers

66 and 81 do not move down with the chuck 29 but rather move upwardly as the chuck commences its downward movement. Therefore, the springs 59 and 78 cause the associated yokes 54 and 73 to move upwardly with respect to the frame 28 and the chuck 29 until the clamping mechanisms are both locked to grip the blank both axially and radially.

As soon as the clamping mechanisms are locked further upward movement of each yoke 54 and 73 with respect to the associated

cam lever

84 and 67 stops as soon as grip pressure is applied to the blank 33 and the

rods

56 and 77 move with the chuck 29. When this occurs the contact between the

rods

56 and 77 and the associated

rollers

66 and 81 is not maintained. As soon as the

rods

56 and 77 move out of contact with their associated

rollers

66 and 81, the forces of the springs 59 and 78 are transmitted from the upper side of the chuck 29 back to the chuck through the associated cam levers 48 and 67 so these springs do not continue to function to urge the chuck in the downward direction. With this arrangement the forces of the springs 59 and 78 are available to initiate downward movement of the chuck 29 but after the initial downward movement and after the gripping is completed, only the main spring 107 acts to urge the chuck in a downward direction.

After the cutting is completed, the cam 26 through its drive linkage causes the chuck 29 to move back up toward its loading position. Because a positive mechanical drive is provided for this movement, rapid acceleration can be achieved without difficulty. The cam 27 is shaped to move the

rollers

66 and 81 in an upward direction as the chuck approaches the loading or upper position but at a slower rate of movement than the rate of chuck movement. Therefore, the

rods

56 and 77 engage the

rollers

66 and 81 respectively with a relative velocity which is less than the velocity of the chuck. This reduces impacting upon such engagement. As soon as the upper ends of the

rod

77 and 56 engage their associated rollers, the yokes 54 and 73 do not move upward with the same speed as the chuck so gripping mechanisms are released. Preferably this is timed to occur before the chuck reaches its upper position so that the springs 69 and 78 will assist the main spring 107 in decelerating the chuck to bring it to rest in its upper position. The blank feed mechanism then causes a discharge of the blank which is already been pointed and loading of the subsequent blank for pointing.

Since the gripping of the blank is controlled by a power mechanism, the gripping can be achieved almost as soon as the chuck starts to move down from the loading position. Consequently a shorter chuck travel may be provided in a pointer incorporating this invention than can be incorporated in the Edmondson patent cited above. Since the travel of the chuck can be reduced, the period of the cycle during which the chuck 29 is moved toward the cutter can be reduced and the portion of the total'cycle during which cutting actually occurs can be increased. Therefore, the pointer can be operated through a shorter cycle without materially reducing the time during which the cutting actually occurs. Also the preferred arrangement, wherein gripping is not completed until after the chuck moves a short distance from the loading position and gripping release occurs slightly before the chuck returns to the loading position, results in a system wherein the springs 59 and 78 function to assist in the rapid acceleration and deceleration of the chuck when the grippers are released.

Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifications and arrangements may be resorted to without departing from the scope of the invention disclosed.

l claim:

1. A pointer for blanks comprising a frame, a rotating cutter on said frame, a chuck reciprocal on said frame between a first position in which blanks are delivered to and removed from said chuck and a second position in which a blank carried by said chuck is positioned in cutting engagement with said cutter, gripper means on said chuck operable to releasably grip a blank and hold such blank in a predetermined position with respect to said chuck, first power means operable to cause reciprocal movement of said chuck between said first and second positions, and second power means including a power member movable on said frame operable to cause movement of said gripper means, independent of movement of said chuck, to grip a blank when said chuck is in said second position and to cause said gripper means to be released when said chuck is in said first position in a manner such that the required movement of said chuck is minimized.

2. A pointer as set forth in claim 1 wherein said first power means includes first spring means urging said chuck toward one of said positions and a positive mechanical drive operable to move said chuck toward the other of said positions, and said second power means includes second spring means controllably operable by said movable power member to urge said chuck toward said one position when said chuck is in said other position.

3. A pointer as set forth in claim 2 wherein said one position is said second position, and said other position is said first position, and said second power means is arranged to remove the bias of said second spring means on said chuck toward said second position when said chuck approaches said second position.

4. A pointer as set forth in claim 1 wherein said first power means includes a cam operated linkage operable to allow controlled movement of said chuck from said first position to said second position and to provide positive mechanically driven movement from said second position to said first position, said first power means having first spring means operable to resiliently urge said chuck toward said second position, and said second power means includes a second cam driven linkage operable to release said gripper means when said chuck is adjacent to said first position.

5. A pointer as set forth in claim 4 wherein said gripper means includes separate grippers to axially and radially grip a blank, and said second spring means includes a separate spring associated with each gripper.

6. A pointer as set forth in claim 4 wherein said second linkage includes an elongated operating rod member which is loaded only in tension.

7. A pointer as set forth in claim 4 wherein said gripper means includes an operator element movable with said chuck when said gripper means is engaged, said movable member on said frame moves into engagement with said operator element to release said gripper means, and said cam driven linkages are timed so that said movable member is moving in the same direction as said chuck with a lower velocity than said chuck when said chuck approaches said first position.

a. A pointer as set forth in claim 1 wherein said second power means is operable to actuate and engage said. gripper means as said chuck moves away from said first position and is operable to release said gripper means as said chuck approaches said first position.

9. A pointer for blanks comprising a frame, a pointing tool on said frame, a chuck reciprocal on said frame between a first position in which blanks are delivered to and discharged from said chuck and a second position in which a blank carried by said chuck engages said pointing tool, a drive spring operatively connected between said chuck and frame resiliently urging said chucktoward said second position, first power means operable to allow controlled movement of said chuck toward said second position in response to the force of said drive spring and operable to positively provide controlled movement of said chuck toward said first position, gripper means operable to grip and position a blank in said chuck as said chuck moves toward said second position, said gripper means including an operator element carried by said chuck and movable relative thereto between an operated position in which said gripper means grips a blank to a release position, a gripper spring operatively connected between said operator element and said chuck resiliently urging said operator element toward said operated position, and power driven control means including a movable member operable on said frame independently of movement of said chuck to position said operator element in said operated position when said chuck is in said second position.

lit). A pointer as set forth in claim 9 wherein said gripper spring urges said chuck toward said second position when said gripper is released.

H. A pointer as set forth in claim 9 wherein the force of said gripper spring on said operator element is constant when said operator element is in said operated position.

12. A pointer as set forth in claim 9 wherein the movement of said movable member is timed so that said operator element moves in a direction opposite to the movement of said chuck as said chuck commences to move toward said second position whereby said gripper means is actuated as said chuck commences to move toward said second position.

13. A pointer as set forth in claim 12 wherein the movement of said movable member is timed so that said operator element is engaged to release said gripper means as said chuck approaches said first position.

M. A pointer as set forth in claim 13 wherein the movement of said movable member is timed so that it moves in the same direction as said operator element when engagement is established therebetween.

15. A pointer for blanks comprising a frame, a pointing tool on said frame, a chuck reciprocal on said frame between a first position in which blanks are delivered to and discharged from said chuck and a second position in which a blank carried by said chuck engages said pointing tool, drive spring means operatively connected between said chuck and said frame resiliently urging said chuck toward said second position, first power means operable to allow controlled movement of said chuck towards said second position in response to the force of said drive spring means and operable to positively provide controlled movement of said chuck towards said first position, gripper means operable to grip and position a blank in said chuck as said chuck moves toward said second position, said drive spring means including a secondary drive spring adapted to accelerate or decelerate said chuck when near said first position, second power means maintaining said secondary drive spring operable to accelerate and decelerate said chuck for limited predetermined time periods independent of movement of said chuck during travel of said chuck between said first and second positions.

Claims

8. A pointer as set forth in claim 1 wherein said second power means is operable to actuate and engage said gripper means as said chuck moves away from said first position and is operable to release said gripper means as said chuck approaches said first position.

9. A pointer for blanks comprising a frame, a pointing tool on said frame, a chuck reciprocal on said frame between a first position in which blanks are delivered to and discharged from said chuck and a second position in which a blank carried by said chuck engages said pointing tool, a drive spring operatively connected between said chuck and frame resiliently urging said chuck toward said second position, first power means operable to allow controlled movement of said chuck toward said second position in response to the force of said drive spring and operable to positively provide controlled movement of said chuck toward said first position, gripper means operable to grip and position a blank in said chuck as said chuck moves toward said second position, said gripper means including an operator element carried by said chuck and movable relative thereto between an operated position in which said gripper means grips a blank to a release position, a gripper spring operatively connected between said operator element and said chuck resiliently urging said operator element toward said operated position, and power driven control means including a movable member operable on said frame independently of movement of said chuck to position said operator element in said operated position when said chuck is in said second position.

10. A pointer as set forth in claim 9 wherein said gripper spring urges said chuck toward said second position when said gripper is released.

11. A pointer as set forth in claim 9 wherein the force of said gripper spring on said operator element is constant when said operator element is in said operated position.

14. A pointer as set forth in claim 13 wherein the movement of said movable member is timed so that it moves in the same direction as said operator element when engagement is established therebetween.