US2888049A - Screw inserting machines - Google Patents

Description

May 26, 1959 E. O. PETERSON ET AL SCREW INSERTING MACHINES Filed Jan. 50, 1958 4 Sheets-Sheet 1 lanl Eva/d O- Paenson May 26, 1959 Filed Jan. 30, 1958 E. O. PETERSON ETAL SCREW INSERTING MACHINES 4 Sheets-Sheet 2 as 5e n 73 r ag IE 17/ 69 a7 r 74 L A I 76 Z6 7 68 a2 27 g 70 J 19 rim 60 67 n 69 8 6a 80 J1 \,T 'I as I g; eaq 618 ma 6 9e 63 g. 1&7 i 5 S: 64 me 93 I a l 37 I 9 J I I 88 7 0| as i o 1 a7 i as J 10 m,

l e o as 8 wezzioas f'va/d 9- psv eman v- JS/vn A. J h 9% a M flioflzzeg;

May 26, 1959 E. o. PETERSON ET AL 2,883,049

SCREW INSERTING MACHINES Filed Jan. so, 1958 4 Sheets-Sheet 3 I wezzzw Era/d O- Pe-ferson Q 0 0 7? F".

United States Patent SCREW INSERTING MACHINES Evald 0. Peterson, lLynnfield Center, and John F. Smith, Braintree, Mass, assignors to Compo Shoe Machinery Corporation, Boston, Mass., a corporation of Delaware Application January 30, 1958, Serial No. 712,193

13 Claims. (Cl. 144-32) This invention relates to screw inserting machines, and relates more particularly to machines for securing heels to shoes with screws.

The E. F. Small Patent No. 2,494,494 discloses a machine, that has been widely used for securing heels to shoes' with screws. In such machine, a shoe is placed upon an inverted last with the heel of the shoe held by a pivoted clamp which is held down by air pressure. The last has a screw receiving recess within which a screw is rotated by a screwdriver bit. The bit is driven through a withdrawing clutch by an electric motor, this clutch being of the familar Bendix type used with the starting motors of automobiles. When the screw has reached the desired depth, a limit switch reverses the motor for withdrawing the screwdriver.

A disadvantage of the machine of said patent is that the force for driving the screw into the heel so deflects the heel that when the limit switch reverses the motor to back the screwdriver out, the deflected heel under the pressure of the heel clamp follows it down so that often the screwdriver does not clear the slot of the screw which is partially unscrewed. The deflection of the heel under the screwdriver driving force also results in unknown variations in the depth of the drive of the screw.

Another disadvantage of the machine of said patent is that the sudden reversal of the driving motor for stopping the advance of the screw often results in the breakage of screwdrivers, screw heads and driving components. In a normal day of operation, a driving motor may be reversed as many as 1700 times, resulting in damage which may keep a machine out of operation for substantial periods of time.

A feature of our invention is that an air cylinder is used to advance a screw as well as to clamp the shoe heel, the air pressures in the screw advancing cylinder and in the heel clamping cylinder being so balanced that there is no deflection of a heel under the screwdriver driving force.

Another feature of our invention is that instead of reversing the electric motor which rotates the screwdriver, by a limit switch, when a screw has been driven to the proper depth, limit switches deenergize the motor and apply electric braking to the rotor of the motor so that the latter stops in a fraction of a revolution.

An object of our invention is to drive screws to uniform depths regardless of types of screws and of materials in which screws are driven.

Another object of our invention is to reduce damages to screws, screwdrivers and screwdriving components resulting from the operation of a screw inserting machine.

Other objects of our invention are to reduce maintenance costs and out-of-operation periods of screw inserting machines.

Our invention will now be described with reference to the annexed drawings, of which:

Fig. l is a front elevation, partially in section, of a heel attaching machine embodying our invention;

2,888,049 Patented May 26, 1959 2 Fig. 2 is a side elevation, partially in section, of the machine of Fig. 1; Fig. 3 is an enlarged view, partially in section, of the upper portion of Fig. 2, with a shoe shown clamped in operating position, and

Fig. 4 is a circuit schematic of the controls of the machine.

The machine illustrated by the drawings is designed to attach plastic or wood heels to lasted uppers of shoes by flat or oval head screws of various lengths and sizes.

Referring now to Figs. 1-3 of the drawings, the machine comprises a base casting 10 on which is supported a top casting 11. The underside of the top casting 11 has a depending boss 12 to which a bracket 13 is secured by screws 14. The bracket 13 has a vertically extending bore in which is slidably positioned a shaft 16 having a lower portion 18 of reduced diameter which passes through an opening in the lower portion of the bracket 13 in alignment with the bore. A coiled spring 17 around the shaft portion 18 serves to bias the shaft 16 upwardly. The lower end of the shaft portion 18 is threaded and has nut 19 and locknut 20 screwed thereon and which serve to limit the extent to which the spring 17 can raise the shaft 16. Clamp arm 22 is pivoted at 23 to the upper end of the shaft 16, and has bifurcated lower portions 24 which straddle the bracket 13, and which are pivoted at 26 to a bracket 27 to which is secured by nuts 28 the threaded upper ends of rods 29. The lower ends of the rods 29 are threaded into clevises 30 which are pivoted to cross-member 31. The upper ends of rods 32 are threaded into the cross-member 31, and their lower portions extend through frame plate 33, and have screwed onto their lower ends nuts 34. Coiled springs 35 extend around the rods 32 between the cross-member 31 and the plate 33. The lower end of a piston rod 36 of clamp cylinder 37 contacts the upper side of the cross-member 31 for moving it downwardly when compressed air is admitted into the cylinder 37, against the resistance of the springs 35. I

The upper end of the clamp arm 22 has attached thereto by rivets 38 an upper clamp arm 39 to the upper end of which is attached shaft 40 on which is positioned heel clamp member 41 to which is pivoted heel clamp 42. The member 41 and arm 39 have shoulders into which is threaded a screw 44 which can be rotated by a knurled knob 45 on its upper end to adjust the position of the clamp member 41 along the shaft 40 for adjustably raising or lowering the heel clamp. The clamp member 41 has spaced-apart pivot holes 46 in which pivot pin 47 can selectively be placed for adjusting the position of theheel clamp forwardly or rearwardly.

The upper end of the top casting 11 has an opening through which extends a cap 50 which is secured by screws 51 to the casting 11. Press fitted into the cap 50 is a bushing 52 within which is journalled screwdriver spindle 53. The spindle 53 is connected to the upper end of shaft 54, the lower end of which is attached through coupling 56 and shaft 57 to pulley 58 which is driven through belt 59 by pulley 60 of electric motor 61;

The lower end of the shaft 57 rests against a thrust bearing 62 the bottom of which is contacted by the upper end of piston rod 63 of drive cylinder 64 which serves to raise the screwdriver assembly as will be described later. A clamp 65 is attached to a bearing 66 movable vertically with the shaft 57, has attached thereto a bracket 67 having a switch actuating screw 68 aligned with the actuating plunger of normally open switch 69 which is provided for operating an electric brake in the motor 61 as will be described later. The bracket 67 also has a switch actuating screw 70 in alignment with the actuating plunger of normally closed switch 71 which is provided for deenergizing the motor 61.

Knob 72 of rod 73 which is threaded in frame plate 74 and in plate 75 attached to the bracket 67, can be rotated to raise and lower the switch actuating screws 68 and 70 for varying the points of operation of the switches 69 and 71 respectively. A coiled spring 76 around the rod 73 between the plates 74 and 75 urges the bracket 67 downwardly. Coiled springs 77 between the clamp 65 and frame member 78 urge the clamp 65 downwardly for returning the screwdriving assembly to its retracted position when the air in the cylinder 64 is released as will be described later.

Bolt 79 threaded into bracket 13 has its inner end in a milled slot (not shown) in the sleeve of the bearing 66 for preventing the latter from rotating.

A strap 81 attached to the clamp 65 has a switch actuating screw 80 in alignment with the actuating plunger of switch 82 which is normally closed, and which is a brake cutout switch as will be described later.

Foot treadle 85 is pivoted by clevis 86 to the lower end of rod 87 which carries switch actuator 88 which is aligned with the actuating plunger of normally open switch 89 which is provided for energizing drive solenoid-valve 90 which admits compressed air from a conventional compressed air source which is not shown, into the drive cylinder 64. The switch actuator 88 is also aligned with the actuating plunger of normally open switch 91 which energizes solenoid-valve 92 which admits compressed air through piping 97 into the clamp cylinder 37. Coiled spring 93 around the upper end of rod 87 and supported between frame member 94 and washer 95 under the nuts 96 threaded on the upper end of the rod 87, returns the treadle 85 to its normal position when pressure against it is released.

Structural angles 125 form horizontal, frame supporting ribs, and to one of the angles is attached an electrical junction box 126 having a terminal strip 127 on one of its sides.

Referring now to Fig. 4 of the drawings, the switch 100 when closed, connects lines L1, L2 and L3 of the control circuit to a three-phase supply source which is not shown. The primary winding 104 of transformer 105 is connected across L1 and L2 so that the transformer is energized when the switch 100 is closed. When the clamp switch 91 is closed, it connects the clamp solenoid 92, through Wires 113, across the secondary winding 110 of the transformer 105. When the drive switch 39 is closed, it connects, through wires 111, the drive solenoid 90 across the secondary winding 110, and connects through wires 112 and 108 and the normally closed motor stop switch 71, the energizing winding 101A of the magnetic starter 101 across the secondary winding 110.

A counter 119 is shunted across the energizing winding 101A, this counter being conventional.

When the magnetic starter 101 is energized, it closes its normally open switches 114, 115, 116, 117 and 118, and opens its normally closed switch 106. The switches 114, 115 and 116 connect the motor 61 to the lines L1, L2 and L3. The switches 117 and 118 provide holding circuits for maintaining the solenoids 90 and 92 and the magnetic starter 101 energized so as to complete a cycle of operation when the switches 89 and 91 open as a result of the operator having lifted his foot from the treadle.

The normally closed brake cut-out switch 82, the normally open brake energizing switch 69, and the normally closed motor switch 71 are actuated by the up movement of the rotary spindle as previously described.

The switch 70, when opened, opens the previously described energizing circuit of the magnetic starter 101.

The brake winding 102 of the motor 61 is connected through the normally open brake switch 69 and the normally closed switch 106 of the magnetic starter 101 and wires 120 to the supply lines L1, L2 and L3.

Valves V1 and V2 are provided for adjusting the air pressures supplied into the drive cylinder 64 and the clamp cylinder 37 respectively. The air pressure would be higher in the clamp cylinder than in the drive cylinder so that the upward movement of the screwdriver bit cannot displace the heel clamp.

The clamp switch 91 is of the type that is opened by pressure against its actuating plunger, and is closed when such pressure is removed. Thus, the switch 91 is open when the treadle is in the normal, up position, and is closed when the treadle is depressed sufiiciently to remove the switch actuator 88 from its plunger.

Figs. 1 and 2 show the treadle in its fully depressed position.

The valves of the clamp and drive solenoids are of the usual type which admit compressed air into the clamp and drive cylinders respectively, when their respective solenoids are energized, and which permit the cylinder to exhaust the previously supplied air when their respective solenoids are deenergized.

Operation In operation, an operator would turn the switch to on position. Next he would place a screw head first into the opening in last post stern 131. A last 132 with an upper 133 thereon would be placed on the heel post stem 131, and a heel 134 would be properly positioned on the lasted upper. The operator would then depress the treadle 85 about half way. This will close the switch 91 and energize the solenoid 92, supplying air to the clamp cylinder, causing the piston rod of the latter to bring through the cross member 31, the rods 29, the clamp arm portions 24 and 22, and upper clamp arm 39, the heel clamp 42 into position on the heel. The clamp arm swings about pivot 23, and the shaft 16 moves downwardly causing the heel clamp 42 to apply a vertically directed down force to the heel for holding it in position for screw insertion. As long as the treadle is not fully depressed, this adjustment can be repeated until the heel is satisfactorily positioned.

The treadle is then fully depressed and closes the switch 89 which closes the previously described circuit to energize the magnetic starter 101 which starts the motor 61, and closes the previously described energizing circuit of the solenoid 90 causing it to supply air to the drive cylinder 64. The piston rod of the latter raises the thrust bearing 62, the shaft 57 and the spindle 53 while the latter is being turned by the motor 61 through the pulleys 58 and 60. The blade of the spindle enters the slot of the screw and drives the screw into the heel.

The motor will continue to rotate the spindle, and the drive cylinder will continue to lift the spindle until the switch actuator bracket 67 contacts the plungers of the switches 69 and 71. The normally closed switch 71 is opened and deenergizes the motor 61. The normally closed switch 69 closes and energizes the previously described brake winding 102, causing the rotor of the motor 61 to come quickly to a stop. The switch 71 can be opened when the switch 69 closes but it is preferred that the switch 71 be opened just before the switch 69 closes. The times at which the switches 69 and 71 can be actuated together can be adjusted as previously described, by rotat ing the knob 72 on the rod 73. Independent adjustment can be made by rotating the plunger contacting screws 68 and 70.

The spindle will remain in its up position under the action of the drive cylinder 64 until the operator removes his foot from the threadle at which time the treadle return springs 93 disengage the switch actuator from the switch 89 and deenergize the solenoid 90 which supplied compressed air into the drive cylinder, following which the drive cylinder exhausts the air previously supplied into it.

The clamp arm 39 will remain in heel holding position until the switch actuator 89 rises upon release of the treadle, and opens switch 91 which deenergizes the solenoid, allowing air to exhaust from the clamp cylinder 37, following which the springs 35 cause the rods 29 to lift and to swing the heel clamp 42 away from the shoe heel.

Since the electric braking is applied through the switch 106 which is closed by the magnetic starter 101 only when the latter and the motor 61 are deenergized, the energizing circuits of the motor and brake cannot be completed at the same time. After a screw has been driven into a heel, the brake stays on as long as the operator keeps the treadle fully depressed.

The brake cut-out switch 82 is located and adjusted so as to be opened after the switch 69 is closed and the switch 71 is opened, and is used to deenergize the electric brake winding 102 when there is no shoe on the last post stern. There being no heel to oifer resistance, the spindle will rise higher than in heel attaching operation, and will open the switch 82, deenergizing the electric brake, and permitting an operator to change the screwdriver bit.

What we claim as our invention is:

1. In a screw inserting machine, a work support, a rotatable spindle, a screwdriver mounted on said spindle, means including an electric motor for rotating said spindle in a screw driving direction, said motor having an electrical braking winding, means for energizing said motor and for moving said spindle towards said work support, and means for deenergizing said motor and for energizing said braking winding after said spindle has moved a predetermined distance towards said support.

2. The invention in claim 1 in which means is provided for deenergizing said braking winding when said spindle has moved a predetermined distance towards said work support greater than said first mentioned predetermined distance.

3. In a screw inserting machine, a work support, a rotatable spindle, a screwdriver mounted on said spindle, means for rotating said spindle in a screw driving direction, means including a fluid cylinder into which fluid under pressure is supplied for moving said spindle towards said work support, means for supplying fluid under pressure into said cylinder, an operator actuated member, and means actuated after a predetermined movement of said member for causing said supply means to supply fluid under pressure into said cylinder.

4. In a screw inserting machine, a Work support, a rotatable spindle, a screwdriver mounted on said spindle, means for rotating said spindle in a screw driving direction, means including a first fluid cylinder into which fluid under pressure is supplied for clamping a work article upon said work support, means including a second fluid cylinder into which fluid under pressure is supplied for moving said spindle towards said work support, first means for supplying fluid under pressure into said first cylinder, second means for supplying fluid under pressure into said second cylinder, an operator actuated control member, means actuated by the movement of said member a predetermined distance for causing said first supply means to supply fluid into said first cylinder, and means actuated by the movement of said member a predetermined distance greater than said first mentioned predetermined distance for causing said second supply means to supply fluid into said second cylinder.

5. The invention claimed in claim 4 in which means is provided for starting said spindle rotating means, and in which means including means actuated by said movement of said member said predetermined distance greater than said first mentioned predetermined distance is provided for actuating said starting means to start said spindle rotating means.

6. In a screw inserting machine, a work support, a rotatable spindle, a screwdriver mounted on said spindle, means including an electric motor for rotating said spindle in a screw driving direction, means including a first fluid cylinder into which fluid under pressure is supplied for clamping a work article on said support, means including a second fluid cylinder into which fluid under pressure is supplied for moving said spindle towards said work support, means including a first solenoid, when energized, for supplying fluid under pressure into said first cylinder, means including a second solenoid, when energized, for, supplying fluid under pressure into said second cylinder, means including a first normally open switch for energizing said first solenoid, means including a sec ond normally open switch for energizing said second solenoid and for energizing said motor, an operator actuated control, means movable with said control for closing said first switch when said control has been moved a predetermined distance by an operator, and means movable with said control for closing said second switch when said control has been moved a predetermined distance greater than said first mentioned distance by an operator.

7. The invention claimed in claim 6 in which said motor energizing means includes a third normally closed switch, and in which means movable with said spindle is provided for opening said third switch when said spindle has moved a predetermined distance towards said work support.

8. The invention claimed in claim 7 in which said motor has an electric braking winding, in which means including a fourth normally open switch is provided for energizing said braking winding, and in which said means movable with said spindle is provided with means for closing said fourth switch.

9. The invention claimed in claim 8 in which a fifth normally closed switch is provided and connected in series with said fourth switch, and in which said means movable with said spindle is provided with means for opening said fifth switch after said fourth switch is closed.

10. In a screw inserting machine, a work support, a rotatable spindle, a screwdriver mounted on said spindle, means including an electric motor for rotating said spindle in a screw driving direction, means including a first fluid cylinder into which fluid under pressure is supplied for clamping a work article upon said work support, means including a second fluid cylinder into which fluid under pressure is supplied for moving said spindle towards said work support, means including a first solenoid, when energized, for supplying fluid under pressure into said first cylinder, means including a second solenoid, when energized, for supplying fluid under pressure into said second cylinder, means including a first normally open switch for energizing said first solenoid, a magnetic starter for said motor, said starter having an energizing winding, means including a second normally open switch for energizing said second solenoid, means including said second switch and a third normally closed switch for energizing said starter winding, said motor having an electric braking winding, means including a fourth normally open switch and a fifth normally closed switch in series with said fourth switch and said braking winding for energizing said braking winding, said fifth switch being connected to said starter and being opened by said starter when said starter winding is energized, an operator actuated control, means movable with said control for closing said first switch when said control has been moved a predetermined distance by an operator, means movable with said control for closing said second switch when said control has been moved a predetermined distance greater than said first mentioned predetermined distance by an operator, and means movable with said spindle for opening said third switch and closing said fourth switch when said spindle has moved a predetermined distance towards said work support.

11. The invention claimed in claim 10 in which said means for energizing said braking winding includes a sixth normally closed switch in series with said fourth and fifth switches and said braking winding, and in which said means movable with said spindle includes means for opening said sixth switch after said fifth switch has been closed by movement of said spindle towards said Work support.

12. The invention claimed in claim 11 in which said starter is provided with switches which are closed when said starter winding is energized and which are connected across said first and second switches for forming holding circuits.

3 13. The invention claimed in claim 10 in which said starter is provided with switches which are closed when said starter Winding is energized and which are connected across said first and second switches for forming 5 holding circuits.

No references cited.

Images