JPH0472660B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides an automatic screwdriver configured to eliminate the influence of inertia of a driver bit when screw tightening is completed and to reliably tighten screws with a desired screw tightening torque. Regarding tightening machines.

Conventional technology Conventionally, in order to eliminate the influence of the inertia of the driver bit when screw tightening is completed, devices generally tighten the screw at high speed and low torque until the screw is seated on the workpiece, and then tighten the screw at low speed and high torque after seating. It is true. An example of this type of device is a power screw tightening machine with an automatic transmission described in Japanese Utility Model Publication No. 51-14556. In this screw tightening machine, as shown in FIGS. 8 and 9, the drive shaft of the motor 19 is connected to the planetary gear mechanism 4.
1 drive gear 42, and this drive gear 4
2 meshes with a ring gear 43 via a planetary gear 44. The planetary gear 44
The rotation is transmitted to the output shaft 45 via the carrier pin 49. The ring gear 43 is connected to the output shaft 45 via a slip clutch 46, and when a reaction torque of a predetermined torque or more is applied to the ring gear 43 due to the load torque of the output shaft 45, the output shaft 45 and the ring gear After the planetary gear 44 is disengaged from the ring gear 43, the planetary gear 44 rotates independently along the ring gear 43, thereby rotating the output shaft 45.

In this screw tightening machine, until the screw is seated on the workpiece, the rotation speed of the motor 19 is transmitted to a driver bit (not shown) at the tip of the output shaft 45 via the planetary gear 44, and the screw is driven at high speed and low torque. It can be tightened with. After that, when the screw comes into contact with the workpiece and the tightening torque approaches the predetermined torque,
The slip clutch 46 is disengaged. Therefore, the ring gear 43, which was rotating together with the output shaft 45, is rotated by the planetary gear 44 and receives a rotational force in the opposite direction, but is stopped at that position by the stop plate 47 and the one-way stopper 48. Therefore, the planetary gear 44 is the ring gear 43.
rotate along. Therefore, the rotation speed of the motor 19 is reduced according to the gear ratio of the planetary gear 44 and the ring gear 43, so that the screw is tightened at low speed and high torque.

Problems to be Solved by the Invention In the screw tightening machine described above, the rotational speed of the driver bit is reduced immediately before screw tightening is completed, but the reduction ratio is determined by the gear ratio between the planetary gear 44 and the ring gear 43. However, there are limitations to the size of the device, and there is also a limit to the deceleration of the driver bit, and the number of rotations of the motor 19 must be set low in advance, resulting in the disadvantages that it takes a long time to tighten the screws. is occurring. Moreover, the driver bit continues to rotate, although it is decelerated, so when the driver bit stops, the motor 1
It is not possible to completely eliminate the influence of inertia of the rotary drive unit including 9, and there is a drawback that the screw is tightened to a predetermined torque or higher, making it impossible to perform accurate tightening work.

Means for Solving the Problems The present invention aims to eliminate the above-mentioned drawbacks.
An input disk of a differential planetary mechanism that rotates in response to rotation of a drive shaft of a rotational drive source is provided in a space formed by a housing and an inner cylindrical portion. A plurality of planetary cones having circumferential grooves are arranged on the input disk so as to be frictionally engaged with each other. Furthermore, a cam disk is arranged to frictionally engage with the flat surface on the back side of the planetary cone, and the rotation of the input disk is taken out as rotation of the cam disk via the planetary cone. . Further, a driver bit is connected to the cam disk so as to rotate in response to the rotation of the cam disk.

A speed change ring is arranged so as to be frictionally engaged with the conical surface of the planetary cone, and this speed change ring is held by a plurality of elastic holding members having one end fixed, and the amount of movement on the high speed side is controlled by the elastic force. The gear ring 25 is configured to be restricted by the holding member, and is configured to be able to rotate the speed change ring 25 by the load torque related to the driver bit and to be able to slide in the axial direction along the conical surface 23c. Further, a torque adjustment sleeve is slidably disposed to fit on the outer periphery of the inner cylindrical portion and has a flange provided with a plurality of notched grooves. is configured such that one end of the elastic holding member engages with the elastic holding member. Furthermore, the torque adjustment sleeve is configured to be moved in the axial direction by an adjustment bolt to change the position of the notch groove relative to the elastic holding member.

Function In the automatic screw tightening machine described above, when the rotational drive source rotates, the input disk of the differential planetary mechanism rotates. Along with this, the planetary cone that is frictionally engaged with the input disk revolves while rotating, and the rotation of the planetary cone is transmitted to the cam disk. This cam disk rotates while being reduced in speed 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 bit. after that,
When the driver bit tightens the screw and the torque applied to the driver bit increases, a reaction torque corresponding to the load on the driver bit is applied to the speed change ring. When the speed change ring rotates along the conical surface of the planetary cone, the elastic holding member that holds it bends and tilts, its vertical length becomes shorter, and the speed change ring slides along the conical surface. move. Therefore, as the speed change ring rotates, the position of frictional engagement between the speed change ring and the conical surface moves toward the low speed side. The speed change ring moves to a position where the pressing force that presses the elastic body generated by the reaction torque and the elastic force of the elastic holding member are balanced, and stops at that position. Therefore, as the load torque increases, the reduction ratio increases continuously, and eventually the driver bit reaches zero rotation with the predetermined torque being maintained even though the input disk is rotating, and the screw Tightening is completed.

In order to change the torque of the driver bit at this time, before starting work, the adjustment bolt is rotated and the torque adjustment sleeve that is threaded onto the adjustment bolt is moved along the inner cylindrical portion. As the torque adjustment sleeve moves, the position of the notch in the collar moves, the bending position of the elastic holding member changes, and the spring constant of the elastic holding member changes. Therefore, the output shaft of the differential planetary mechanism at which the driver bit makes zero rotation, that is, the output torque of the driver bit, can be changed, and a desired torque can be set.

Embodiments Hereinafter, embodiments will be described 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 fixed plate 4 is fixed to this support column 3, and upper brackets 5 are attached to this fixed plate 4 above and below.
and the lower bracket 6 are fixed. A cylinder 7 is fixed to the upper bracket 5, and a driver mounting base 8 is fixed to its rod (not shown). A chuck stand 10 elastically biased by a first spring 9 is arranged at a predetermined interval on the driver mounting stand 8,
The driver mounting base 8 is configured to move together with the driver base 10 along a guide shaft 11 to a predetermined position. Further, a driver main body 12 is fixed to the upper part of the driver mounting base 8, and this driver main body 12 is connected to the connecting mechanism 1.
The driver bit 14 is configured to be rotated via the screwdriver bit 3. On the other hand, a chuck unit 15 is fixed to the chuck base 10, and the driver bit 14 is connected to the chuck unit 15.
It is configured such that a screw (not shown) held by a chuck claw 15a is inserted into a predetermined position.

The driver main body 12 has an inner cylinder part 17 fixed to the driver mounting base 8 via a fixture 16, and a housing 18 integrated with this bottom part 17a. Furthermore, this driver body 12 has a motor 19 as a rotational drive source fixed to the housing 18, and a drive shaft 19a of the motor 19 is located in a space formed by the housing 18 and the inner cylindrical portion 17 to form an automatic transmission. The input disk 21 of the differential planetary mechanism 20 is connected. This input disk 21 has an annular portion 21a on its outer periphery, and this annular portion 21a is a transmission surface formed by circumferential grooves 23a of a plurality of planet cones 23 held with their axes inclined by a cone holder 22. It is configured to frictionally engage with. Moreover, this planetary cone 23 has a flat surface 23b on the back surface,
A cam disk 24 is frictionally engaged with this flat surface 23b, and holds this planetary cone 23 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, and the amount of movement of this speed change ring 25 on the high speed side is determined by the distance between the speed change ring 25 and the bottom 17a of the inner cylindrical portion 17. It is configured to be restricted by an elastic retaining member provided between.
This elastic holding member consists of multiple piano wires 2 to be described later.
6, and as the piano wire 26 bends, the speed change ring 25 bends over the conical surface 23.
It is configured to slide along the curve c to change its frictional engagement position and continuously increase the reduction ratio. Further, the cam disc 24 is configured to rotate at zero when the frictional engagement position of the speed change ring 25 reaches the position shown in FIG. 4 (a position satisfying a:b=c:d). .

A pressure regulating mechanism 27 is connected to the cam disc 24, and the cam disc 24 is connected to the planetary cone 23.
It is configured to press. Further, the pressure regulating mechanism 27 has a connecting shaft 28, which passes through the cam disk 24 and is rotatably held via a bearing fixed to the upper part of the inner cylindrical portion 17. ing. An oil seal mechanism is disposed around the connecting shaft 28, 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. .

Furthermore, a clutch shaft 29 is connected to the connecting shaft 28, and a drive clutch portion 3 is connected to the lower end of the clutch shaft 29.
0 is rotatably inserted. Moreover, this drive clutch portion 30 and the clutch shaft 29 are connected to the second
The connecting mechanism 1 is connected by a spring 31.
The second spring 31 absorbs the inertia of the driver bit 3 and the driver bit 14 during their rotation. A driven clutch portion 32 is rotatably disposed below the driving clutch portion 30, and the clutch shaft 29 is inserted into the driven clutch portion 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 3
4 has a hemispherical portion at its tip, and this locking pin 34 engages with a pin 35 implanted in the clutch shaft 29, so that the rotation of the clutch shaft 29 is constantly transmitted to the driven clutch portion 32. has been done. Further, the driven clutch portion 32 is connected to the driven clutch shaft 3.
2a, the connecting mechanism 13 is connected to the driven clutch shaft 32a, and the rotation of the motor 19 is transmitted to the driver bit 14.

On the other hand, as shown in FIG. 5, a torque adjustment sleeve 36 is slidably 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 serving as linear elastic holding members are fixed between the speed change ring 25 and the shift ring 25 . This piano wire 26 is configured so that when it bends and tilts due to the rotation of the speed change ring 25, its length in the vertical direction becomes shorter. Further, the torque adjustment sleeve 36 has notched grooves 36a at equal intervals on its outer periphery, and the piano wire 26 is configured to pass through the notched grooves 36a. The torque adjustment sleeve 36 has a flange portion, into which an adjustment bolt 37 rotatably held at the bottom 17a of the inner cylindrical portion 17 is screwed. By changing the height position of the sleeve 36, the spring constant of the piano wire 26 changes, so that an elastic force corresponding to the tightening torque can be obtained.

In the above automatic screw tightening machine, when the motor 19 rotates, the rotation is transmitted from the input disk 21 to the cam disk 24 via the planetary cone 23, and the speed change ring 25 frictionally engages with the conical surface 23c of the planetary cone 23. It is decelerated by a reduction ratio determined by the position. This rotation of the cam disk 24 is transmitted to the drive clutch section 30. At this time, the drive clutch portion 3
0 and the driven clutch portion 32 are not fitted,
Pin 35 of clutch shaft 29 and driven clutch portion 32
The rotation of the cam disc 24 is transmitted to the driver bit 14.

In this state, when the driver body 12 is lowered by the operation of the cylinder 7, the driver bit 14 is fitted into the screw in the chuck pawl 15, and the screw is seated on the workpiece, and the relative relationship between the connecting mechanism 13 and the driver bit 14 is Due to this upward movement, the driven clutch portion 32 also rises relatively against the third spring 33. Therefore, the engagement between the pin 35 on the clutch shaft 29 and the locking pin 34 of the driven clutch section 32 is released, and then the driving clutch section 30 and the driven clutch section 32 are brought into mesh with each other. 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 the tightening torque of the screw increases, the speed change ring 25 receives a reaction torque in accordance with the load torque applied to the driver bit 14, and the piano wire 26 bends and tilts as shown in FIG. Therefore, the length of the piano wire 26 in the vertical direction becomes shorter, and the speed change ring 25 moves down along the conical surface 23c of the planetary cone 23 against the elastic force of the piano wire 26. The speed change ring 25 moves to a position where the pressing force against the piano wire 26 caused by the reaction torque and the elastic force of the piano wire 26 are balanced, and then stops.

Further, as the tightening torque increases, the shift ring 25 continues to move, and the reduction ratio of the differential planetary mechanism 20 increases, until finally, even though the input disk 21 rotates, the cam disk 24 becomes zero rotation, and the driver bit becomes 14.
stops with the predetermined torque maintained, and the screw tightening is completed.

In addition, when changing the torque of the driver bit 14 at this time, before starting work, rotate the adjustment bolt 37 and move the torque adjustment sleeve 36 that is threaded onto the adjustment bolt 37 along the inner cylinder part 17. As the torque adjustment sleeve 36 moves, the position of its collar moves, the bending position of the piano wire 26 changes, and the spring constant of the piano wire 26 changes. Therefore, the torque possessed by the driver bit 14 when the speed change ring 25 rotates by a predetermined angle and the driver bit 14 reaches zero rotation can be changed, and a desired torque can be set.

Effects of the Invention As explained above, the present invention transmits the rotation of the rotational drive source to the driver bit through the frictional engagement of the input disk, the planetary cone, and the cam disc, and the transmission ring that is frictionally engaged with the conical surface of the planetary cone. is arranged, and the amount of movement on the high-speed side is limited by an elastic holding member, and a torque adjustment sleeve having a flange provided with a notched groove that determines the bending position of the elastic holding member is attached to the cylindrical part. The adjustment bolt is screwed into the flange of the torque adjustment sleeve, and the torque adjustment sleeve is moved as the adjustment bolt rotates, so that the load torque of the driver bit is reduced. The speed change ring rotates in response to the reaction torque corresponding to In addition to eliminating the influence of inertia, rotating the adjustment bolt moves the torque adjustment sleeve, changes the bending position of the elastic holding member, changes the spring constant of the elastic holding member, and stops rotation when tightening is complete. There are advantages such as being able to arbitrarily change the torque of the output shaft of the differential planetary mechanism, that is, the driver bit, and obtaining a desired final tightening torque.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the main part 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. A sectional view of the main parts showing the operating state of the moving planetary mechanism,
FIG. 5 is a perspective view of the main part of the torque adjustment ring according to the present invention, FIG. 6 is an enlarged perspective view of the main part seen from line A-A in FIG. 1, and FIG. 7 is a main part showing the operating state of the present invention. FIG. 8 is a sectional view of a main part of the conventional example, and FIG. 9 is a sectional view taken along line BB in FIG. 8. 1... Automatic screw tightening machine, 2... Base, 3... Support column, 4
...Fixing plate, 5...Upper bracket, 6...Lower bracket, 7...Cylinder, 8...Driver mounting base, 9
...first spring, 10...chuck stand, 11...guide shaft, 12...driver body, 13...coupling mechanism,
14...driver bit, 15...chuck unit, 15a...chuck claw, 16...fixing tool, 17...
Inner cylinder part, 17a...bottom, 18...housing, 19
...Motor, 19a... Drive shaft, 20... Differential planetary mechanism, 21... Input disk, 21a... Annular part, 22... Cone holder, 23... Planetary cone, 23a... Circumferential groove, 23b... Flat part, 23c... Conical surface, 24... Cam disk, 25... Speed change ring, 26... Piano wire, 27... Pressure regulating mechanism, 28... Linking shaft, 29... Clutch shaft, 30... Drive clutch portion, 31... Second spring, 32... Driven clutch Part, 32a... Driven clutch shaft, 33... Third spring, 34... Locking pin, 35...
Pin, 36... Torque adjustment sleeve, 36a... Notch groove, 37... Adjustment bolt, 41... Planetary gear mechanism, 4
2... Drive gear, 43... Ring gear, 44... Planetary gear, 45... Output shaft, 46... Slip clutch, 47... Stopper plate, 48... One-way stopper, 49... Carrier pin.

Claims (1)

[Scope of Claims] 1. An input disk 21 of a differential planetary mechanism 20 that rotates in response to the rotation of a drive shaft 19a of a rotational drive source is provided in a space formed by a housing 18 and an inner cylindrical portion 17. A plurality of planetary cones 23 having circumferential grooves 23a that frictionally engage with the plate 21 are attached to the cone holder 22.
A cam disk 24 is arranged so as to be rotatably attached to the planetary cone 23, and a cam disk 24 is arranged so as to frictionally engage with the flat surface 23b on the back surface of the planetary cone 23, and a driver bit 14 which rotates in response to the rotation of the cam disk 24 is connected to the cam disk 24. On the other hand, a speed change ring 25 that frictionally engages with the conical surface 23c of the planetary cone 23 is disposed, and this speed change ring 2
5 is connected to an elastic holding member whose one end is fixed to the inner cylindrical portion 17 side, so that the amount of movement of the speed change ring 25 on the high speed side is limited by the elastic holding member, and the speed is changed by the load torque related to the driver bit 14. The ring 25 is configured to be rotatable and slidable in the axial direction along the conical surface 23c,
Fits into the outer periphery of the inner cylindrical portion 17 and has a plurality of notch grooves 3
A torque adjustment sleeve 36 having a flange provided with a flange 6a is slidably disposed, one end of a plurality of elastic holding members is engaged with the notch groove 36a, and the torque adjustment sleeve 36 is aligned with the axis via an adjustment bolt 37. An automatic screw tightening machine characterized in that the engagement position of the notch groove 36a with respect to the elastic member is changed by moving the screw in the direction.