JPS6234731A - Automatic thread tightening machine - Google Patents

Abstract

PURPOSE:To enable a machine to be prevented from being influenced by inertia of a driver bit when the machine completes thread tightening, by transmitting rotation of a rotary driving source to the driver bit through an automatic transmission consisting of a differential planetary mechanism having a planet cone. CONSTITUTION:If a motor rotates, its rotation is transmitted to a cam disc 24 reducing a speed in reduction ratio determined by a position where a speed change ring 25 engages by friction with a conical surface 23c of a planet cone 23. The rotation of said cam disc 24 is transmitted to a driving clutch part 30. Here the driving clutch part 30 is not fitted to a driven clutch part 32, but a machine, engaging a pin 35 of a clutch shaft 29 with a stop pin 34 of the driven clutch part 32, transmits the rotation of the cam disc 24 to a driver bit. Under this condition, if a driver main unit 12 lowers by action of a cylinder, the machine, releasing the pin 35 from its engaging condition with the stop pin 34, meshes the driving clutch part 30 with the driven clutch part 32.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is directed to improving the habit of a driver bit when screw tightening is completed.
This invention relates to an automatic screw tightening machine that is configured to eliminate the influence of 1 and perform 61C screw tightening with a desired screw tightening torque.

Conventional technology Conventionally, when tightening a screw to a workpiece, the desired tightening of a screw is determined by the torque, and the load current flowing through the armature winding of the motor that transmits rotation to the driver bit is statically proportional to the torque. A screw tightening method is used in which the load current is detected, and when the load current reaches a preset value, the voltage supply to the motor is stopped and the screw tightening is completed.

Problems to be Solved by the Invention In this screw tightening method, even if the voltage supply to the motor is stopped when the screw is seated on the workpiece and the load current reaches the setting 1, the motor still rotating at high speed can be Since the electric bolt undergoes rapid deceleration, the inertial force of the electric bolt applies an output torque unrelated to the load current in the tightening direction, and the actual tightening value is as shown in Figure 9. As shown in Figure 9, the torque value is larger than the one determined by the charging current, and its magnitude is not constant because it is due to the chest force, making it extremely inaccurate.
Accurate tightening has disadvantages such as inability to control torque. Furthermore, this method of tightening has disadvantages such as if the circuit for comparing the load current and the set value breaks down, the tightening operation cannot be performed at all.

Means for Solving the Problems The present invention aims to eliminate the above-mentioned drawbacks, and uses a differential planetary mechanism in which the reduction ratio changes continuously according to the load on the output side, so that the reduction ratio can be increased to infinity. Differential planetary machine 414 when reached
Screw tightening is performed using a constant transmission force generated by the boundary lubrication effect on the frictional engagement surface of the screw. A rotary drive source is fixed to one end of the driver body, and the rotation of the drive shaft is configured to be transmitted to the input disk of the differential planetary mechanism. A plurality of planetary cones are arranged on this input disk so as to be frictionally engaged with it, and a cam disk is also frictionally engaged with this planetary cone, and transfer is possible by receiving the rotation of the cam disk. It is located. Further, a driver bit is connected to the cam disk so as to rotate together with the cam disk, and the rotation of the input disk is taken out as rotation of the cam disk via a planetary cone and transmitted to the driver bit. ing.

A speed change ring is arranged to frictionally engage with the conical surface of the planetary cone, and the amount of movement of this speed change ring on the high speed side is limited by an elastic holding member disposed within the tribar body. Furthermore, the speed change ring is configured to be rotatable by the load torque of the driver bit and slidable along the conical surface in the axial direction of the speed change ring. Further, the speed change ring is configured to be movable toward the larger diameter side of the conical surface against the elastic force of the elastic holding portion H until the driver bit stops. Further, even though the rotary drive source is rotating, when the driver bit stops, a constant 1-torque is outputted, and the screw is finally tightened with this torque.

Function: In this automatic screw tightening machine, when the rotary drive source rotates, the input disk of the differential planetary mechanism rotates. As a result, the planetary cone that frictionally engages with the input disk rotates and then revolves at that position, and the rotation of the planetary cone is transmitted to the cam disk. This cam disk rotates while reducing the rotational speed of the input disk at a reduction ratio determined by the position where the speed change ring frictionally engages with the conical surface of the planetary cone, and the rotation is transmitted to the driver pin 1-. Thereafter, the driver bit tightens the screw, and the load 1 to torque applied to the driver bit increases, and along with this load torque, reaction torque is applied to the speed change ring, causing the speed change ring to rotate. Along with this, the elastic holding member is inclined, and the speed change ring moves toward the larger diameter side of the conical surface of the planetary cone against the elastic force of the elastic holding member. The speed change ring moves to a position where the axial pressing force generated by the reaction torque and the elastic force of the elastic holding member are balanced, and stops at that position. Therefore, the position of frictional engagement with the circular glt surface of the planetary cone of the speed change ring changes, and the driver bit can gradually tighten the screw at low speed and high torque. As the anti-horn torque applied to the driver bit increases, the reduction ratio also increases continuously, and eventually the driver bit stops rotating even though the input disk is rotating, and the differential planetary ( A constant torque obtained by the boundary lubrication effect of various parts is outputted, and screw tightening is completed with this 1 to 1 torque.
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Examples will be described below with reference to the drawings. In FIGS. 1 to 3, reference numeral 1 denotes an automatic screw tightening machine, which has a support 3 implanted in a base 2. As shown in FIG. A fixing plate 4 is fixed to the support column 3, and an upper bracket 5 and a lower bracket 6 are fixed to the fixing plate 4 above and below. A cylinder 7 is fixed to the upper bracket 5, and a driver mounting base 8 is fixed to the rod (not shown). A chuck stand 10 elastically biased by a first spring 9 is arranged on the driver mount 8 at a predetermined interval. It is configured to move together to a predetermined position along the

Further, a driver main body 1 is provided on the upper part of the driver mounting base 8.
2 is fixed, and this driver body 12 is configured to rotate a driver bit 14 via a connecting mechanism 13.

j5, chuck units 1 to 15 are mounted on the chuck stand 10;
The driver bit 14 is inserted into the chuck unit 15, and a screw (not shown) held by the chuck claw 15a is screwed into a predetermined position.

The driver main body 12 is attached to the driver mounting base 8 with a fixture 1.
6 and the bottom portion 17a of the inner cylinder portion 17 fixed via the
It has a housing 18 that is integrated into the housing.

Moreover, these 1 to Liha main bodies 12 are
A rotary drive source motor 19 fixed to the rotary drive shaft 19a is connected to a large groove 2 (differential planetary, which forms an automatic transmission) on its drive shaft 19a.
0 input disks 21 are connected. This input disk 21
has an annular portion 21a on its outer periphery, and this annular portion 21a frictionally engages with a transmission surface formed by circumferential grooves 23a of a plurality of planetary cones 23 held with their axes inclined by a cone holder 22. It is configured as follows. Moreover, this planetary cone 23 has a flat surface 23b on the back surface, and this flat surface 23b
The cam disc 24 or iIJ lqJ is engaged,
This planetary cone 23 is held between it and the input disk 21. Further, a speed change ring 25 is positioned around the planetary cone 23 so as to be in contact with its conical surface 23c. It is restricted by an elastic holding member provided between the portion 17 and the portion 17. The elastic holding member A is made up of a plurality of piano wires 26, which will be described later, and the piano wires 26 are tilted in response to the reaction torque applied to the speed change ring 25, so that the speed change ring 25 is tilted in its axial direction. It is configured to move 1M per hour. The speed change ring 25 is configured to change the position of frictional engagement with the surface 23C of the circle 11 by moving in its axial direction, so that the rotation speed of the cam disk 24 is reduced by a continuously changing reduction ratio. Further, when the frictional engagement position of the speed change ring 25 almost reaches the position shown in FIG. It is configured to output a constant torque due to boundary lubrication in the mechanism.

A pressure regulating mechanism 27 is connected to the cam disk 24, and the cam disk 24 is configured to press the planetary cone 23. Further, the pressure regulating mechanism 27 is connected to the connecting shaft 2
8, and this connecting shaft 28 is connected to the cam disc 2.
4 and is rotatably held via a bearing fixed to the upper part of the inner cylinder part 17. Said articulation! An oil seal mechanism is arranged around the 1II1 128, and is configured to fill oil between the housing 18 and the inner cylindrical portion 17 to prevent wear of the differential planetary mechanism 20.

Roughly speaking, the connecting shaft 28 is equipped with a clutch Ii! l1129
The drive clutch section 30 is rotatably fitted into the lower end of the drive clutch section 30. This drive clutch portion 30 and the clutch shaft 29 are connected by a second spring 31,
It is configured to reduce the sudden impact that the driver bit 14 receives when the head of the screw is seated. A driven clutch section 32 is rotatably disposed below the drive clutch section 30, and the clutch shaft 29 is inserted into the driven clutch section 32.
0, a third spring 33 is arranged between the two. Further, the driven clutch portion 32 has a hollow portion, and a locking pin 34 is attached to protrude into the hollow portion as shown in FIG. 6.

This locking pin 34 has a hemispherical portion at its tip, and this locking pin 34 engages with a pin 35 implanted in the clutch 1Iill129, so that the rotation of the clutch shaft 29 is constantly transmitted to the driven clutch portion 32. It is configured as follows. moreover,
The driven clutch section 32 has a driven clutch @1132a, the connecting mechanism 13 is connected to the driven clutch 4!11132a, and the rotation of the motor 19 is configured to be transmitted to the driver bit 14. .

On the other hand, as shown in FIG. 5, a torque adjustment sleeve 36 is movably disposed on the outer periphery of the inner cylindrical portion 17, and the bottom 17a of the inner cylindrical portion 17 integrated with the housing 18 and the A plurality of piano wires 26, which are linear elastic bodies and serve as elastic holding members, are fixed between the shift ring 25 and the shift ring 25. This piano wire 26 holds the speed change ring 25 so as to be rotatable and movable by one eye in the axial direction thereof. Further, the piano wire 26 is configured to hold the speed change ring 25 on the high speed side, and to generate a reaction force that returns the speed change ring 25 to the high speed side when the speed change ring 25 begins to rotate. On the other hand, the 1~luke adjustment sleeve 36 has notched grooves 36a at equal intervals on its outer periphery, and is configured so that the piano wire 26 passes through the notched grooves 36a. Further, the torque adjustment sleeve 36 has a flange portion into which an adjustment bolt 37 rotatably held at the bottom 17a of the inner cylinder portion 17 is screwed. Moreover, the spring constant of the piano wire 26 can be changed by changing the height position of the torque adjusting sleeve 36, so that an elastic force corresponding to the tightening torque can be obtained.

In the above-mentioned automatic screw tightening), when the motor 19 rotates, its rotation is reduced by a reduction ratio determined by the position where the speed change ring 25 and the conical surface 23c of the planetary cone 23 frictionally engage, and is transmitted to the cam disk 24. .

This rotation of the cam disc 24 is transmitted to the drive clutch section 30. At this time, the driving clutch section 30 and the driven clutch section 32 are not fitted, but the pin 35 of the clutch shaft 29 and the locking pin 34 of the driven clutch section 32 are engaged,
Rotation of the cam disc 24 is transmitted to the driver bit 14.

In this state, when the driver main body 12 is lowered by the operation of the cylinder 7, the driver bit 14 is fitted into the screw in the chuck claw 15, and the screw is seated on the workpiece, and the connection mechanism 13 and the driver bit 14 are moved relative to each other. Due to this upward movement, the driven clutch portion 32 also rises relatively against the third spring 33. Therefore, pin 3 on clutch shaft 29
5 and the locking pin 34 of the driven clutch section 32 is released, and then the drive clutch section 30 and the driven clutch section 32 are engaged. Along with this, the driver bit 14 is rotated by the output torque of the cam disk, and the screw is screwed into a predetermined position.

When tightening a screw, when the torque increases, the screwdriver bit 1
According to the load torque of the piano wire 2, as shown in FIG.
6 bends while tilting. Therefore, the speed change ring 25 moves in the axial direction against the elastic force of the piano wire 26,
Since the planetary cone 23 moves once along the circle 11E surface 23C, its frictional engagement position changes. The speed change ring 25 stops at a frictional engagement position where the axial pressing force generated from the reaction torque and the elastic force of the piano wire 26 are balanced.

Furthermore, when the screw is seated on the workpiece, the tightening torque increases and the reaction torque increases rapidly. Along with this, the speed change ring 25 moves close to the edge of the large-diameter side of the conical surface, and its reduction ratio increases by more and more, until finally, even though the input disk 21 rotates, the cam The disk 24 has zero rotation. At this time, the driver bit 14 is outputting a constant torque generated by the boundary lubrication effect of the differential planetary mechanism, and with this torque the driver bit 14 can finally tighten the screw.

Furthermore, when the screw is seated on the workpiece, it suddenly increases in size and reaches the specified value of Ω, but since the rotation speed at this time is zero, the screw can be tightened without being affected by the loss of rotational drive parts including the motor 19. can be completed.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention is configured to transmit the rotation of a rotary drive source to a driver bit through an automatic transmission consisting of a differential "item star mechanism" having a planetary cone. As the reaction torque applied to the driver bit due to torque increases, not only can the rotation of the driver bit, which rotates due to rotation from the rotary drive source, be continuously decelerated, but also the desired tightening can be achieved when the torque reaches the desired torque. , the driver bit can be set to zero rotation regardless of the rotation of the rotary drive source, and when screw tightening is completed, it is completely unaffected by the inertia of the driver bit, making it possible to tighten with extremely high precision. In addition, the present invention allows the final tightening to be performed with a constant torque that takes advantage of the boundary lubrication effect of the differential planetary gear, and the torque is also within the range shown in Fig. 8. As shown in the torque characteristic curve, it is always stable at the maximum value, which not only makes torque monitoring extremely easy and accurate, but also ensures that the specified torque is maintained even in the event of a failure of the torque monitoring device. It has advantages such as being able to tighten screws.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of essential parts of the present invention, FIG. 2 is an overall explanatory diagram of the present invention, FIG. 3 is a partially cutaway sectional view of the driver main body according to the present invention, and FIG. 4 is a difference according to the present invention. 5 is a perspective view of the main part of the torque adjustment ring according to the present invention, and FIG. 6 is an enlarged perspective view of the main part taken from line A-A in Fig. 1. Fig. 7 is a sectional view of main parts showing the operating state of the present invention, Fig. 8 is a torque loop diagram of the driver bit of the automatic screw tightening machine of the present invention, and Fig. 9 is a diagram of a conventional screw tightening machine. There is a torque curve diagram C of the 4-driver bit. 1 automatic screw tightening I number, 2 base, 3 pillar,
4 Fixed play 1~. 5 Upper bracket 1
~, 6 lower bracket, 7 cylinder, 8 driver mounting base, 9 first spring, 10 chuck base, 11 kite shirt 1~. 12 driver main body, 13 connecting mechanism, 14 to driver pit, 15 chuck unit, 15a chuck claw, 16 fixture, 17 inner cylinder part,
17a bottom, 18 housing,
19 motor, 19a drive shaft, 20
Differential planetary mechanism, 21 Human power disc, 21a
Annular part, 22 Cone holder, 23 Planetary cone, 23a Circumferential groove, 23b Flat part, 23
c circle, 24 cam disc, 25
Shift ring, 26 Piano wire, 27
pressure regulating mechanism, 28 connecting shaft, 29 clutch rod, 30 drive clutch section, 31 second
Spring, 32 Driven clutch portion, 32a Driven clutch shaft, 33 Third spring, 34 Locking pin, 35 Pin, 36 Torque adjustment sleeve,
36a notch groove, 37 to adjustment pole 1,

Claims (1)

[Claims] A rotary drive source is fixed to one end of the driver body 12, and the rotation of the drive shaft 19a is transmitted to the input disk 21 of the differential planetary mechanism 20. A plurality of planetary cones 23 are arranged so as to be frictionally engaged, a cam disk 24 is frictionally engaged with the planetary cones 23 and arranged to roll under the rotation of the planetary cones 23; 24 and the driver bit 14 so as to rotate together, the rotation of the input disk 21 is extracted as the rotation of the cam disk 24 and transmitted to the driver bit 14, and the conical surface of the planetary cone 23 The speed change ring 25 is disposed so as to frictionally engage with the speed change ring 23c, and the amount of movement of the speed change ring 25 toward the high speed side is limited by an elastic holding member provided in the driver body 12, and the load torque of the driver bit 14 is used to limit the amount of movement of the speed change ring 25 toward the high speed side. The speed change ring 25 is configured to be rotatable and slidable in the axial direction of the speed change ring 25 along the conical surface 23c, and the speed change ring 25 is moved along the large diameter of the conical surface until the rotation of the driver bit 14 stops. 1. An automatic screw tightening machine characterized in that the automatic screw tightening machine is configured to be movable toward the front side, and configured to tighten a screw with a constant output torque generated when a driver bit 14 stops rotating.