JPH0536592Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application The invention provides a rotating part that rotates due to the reaction force applied to the driver bit when tightening a screw, and detects the rotational torque using a torque detection mechanism such as a strain gauge tube. The present invention relates to an automatic screw tightening machine with a torque sensor configured to detect the tightening torque applied to a driver bit.

Conventional technology Conventionally, a screw tightening machine with a torque sensor uses a torque detection mechanism such as a strain gauge tube to extract the reaction force applied to the driver bit, and the amount of displacement is detected by a strain gauge attached to this to determine the tightening torque of the driver bit. A detection mechanism is common. As a method of extracting the reaction force of the driver bit using the strain gauge tube, as shown in FIG. In order to connect the strain gauge tube 16 between the lower end and the driver stand 4 and to fix the motor body 12 to the driver stand 4 as shown in FIG. The reaction force of the driver bit 10 is transmitted to the driver bit 10 and received by the internal gear 51a of the planetary gear mechanism 51, which is held rotatably as a rotating part, and a strain gauge tube is connected between one end of the gear and the driver stand 4. There is a configuration in which 16 are connected.

Problems to be Solved by the Invention The configuration in which the motor body 12 is rotatable can be easily adopted even when using a general reduction gear without using a planetary gear mechanism.
This configuration is widely used in screw tightening machines with torque sensors. Although the output wire from the strain gauge 22 can be easily taken out with this configuration, the lead wire section of the motor is fixed to the base of the screw tightening machine. When doing so, the motor main body 12 may be pulled and rotated, causing the strain gauge tube 16 to be slightly distorted, resulting in drawbacks such as the inability to display an accurate zero point of the torque value. Also, the internal gear 5 of the planetary gear mechanism 51 that fixes the motor body 12 to the driver stand 4
The configuration in which 1a is freely rotatable cannot be adopted when using a general reduction gear, and the planetary gear mechanism 51 must be used, and the rotation speed of the motor at the start of screw tightening will be extremely reduced. This causes disadvantages such as the inability to tighten screws quickly.

Means for Solving the Problems The present invention aims to eliminate the above-mentioned drawbacks, and the motor body is fixed via a support to a driver stand that is arranged to be movable up and down. A storage case is rotatably held between the motor body and the driver stand and is separated from the motor body and has an input shaft that receives the rotation of the motor and an output shaft that transmits the rotation to the driver bit. Further, a torque detection mechanism having an elastic body to which one end of the storage case is locked is fixed to the driver stand, and this torque detection mechanism detects the amount of rotation of the storage case that rotates in response to the reaction force of the driver bit. The tightening torque applied to the driver bit is configured to be detected.

Function In the automatic screw tightening machine with torque sensor configured as above, the motor body is fixed to the driver stand.
Moreover, since the storage case is rotatable relative to the driver stand and the motor body, even if the motor body is pulled when fixing the lead wires of the motor body to the base, the strain gauge tube will not be pulled. Therefore, the zero point of the torque value can be displayed reliably without being affected by it. Also,
When transmitting the rotation of the motor body to the driver bit, there is no need to use a planetary gear mechanism and a general reduction gear can be used, so the rotation of the motor can be reduced at any reduction ratio and transmitted to the driver bit. When screw tightening starts, the driver bit starts rotating at high speed, allowing quick screw tightening work.

Embodiments Hereinafter, embodiments will be described with reference to the drawings. In FIGS. 1 and 2, 1 is an automatic screw tightening machine with a torque sensor, and has a bracket 2 fixed to a base (not shown). This bracket 2
The guide shaft 3 is installed parallel to this.
A driver stand 4 is movably arranged along. This driver stand 4 is connected to a rod (not shown) of a cylinder 5 fixed to the bracket 2, and the driver stand 4 is configured to be able to move up and down by its operation. Further, a chuck stand 6 is disposed on the guide shaft 3 and is elastically biased by a spring 7 so as to be spaced apart from the driver stand 4 by a predetermined distance.
The driver stand 4 moves together until it stops at the lower end of the driver stand 4, after which only the driver stand 4 is movable.
The chuck base 6 has a pair of chuck claws 9a for holding screws (not shown) supplied from the hose 8.
A chuck body 9 having a diameter is fixed thereto, and a driver bit 10 (described later) passes through the chuck body 9 to tighten a screw in a predetermined position.

Further, a motor main body 12 of the motor is fixed to the driver stand 4 via a support 11, and a fitting hole 13a is cut in the drive shaft 13 of the motor. An input shaft 15 housed in a storage case 14, which will be described later, is arranged to fit into the fitting hole 13a, and the motor main body 12 and the storage case 14 are separated to allow the motor main body 12 to move when the motor is driven. Even if vibration occurs, the vibration is not transmitted to the storage case 14, and the strain gauge tube 16, which will be described later, is constructed so as not to be affected by the vibration. Further, the storage case 14 has an output shaft 17 connected to the input shaft 15 via a reduction gear group (not shown) at its lower end, and the output shaft 17 has two universal joints 1.
8a and the length adjustment mechanism 18 located between them
The driver bit 10 is connected via a connecting mechanism 18 consisting of b. The driver bit 10
is arranged so as to be able to pass through the chuck main body 9, and is configured to push out the screw held by the chuck pawl 9a from the chuck pawl 9a and tighten it in a predetermined position.

Further, the storage case 14 is composed of upper and lower cases 14a and 14b, and the storage case 14 is connected to the motor body 12 at the top and to a bearing stand 19 fixed to the driver stand 4 at the bottom. It is held rotatably. An internal tooth serration 20 is fixed to the lower end of the upper case 14a so as to surround the output shaft 17, and this internal tooth serration 20 is connected to the bearing stand 19.
It is configured to be located above. Also,
An internal tooth serration portion 19a is formed at the inner lower portion of the bearing stand 19, and this internal tooth serration portion 19a is formed to have the same shape as the internal tooth serration 20. On the other hand, a bearing guide 21 is fixed to the inner lower end of the bearing stand 19 so as to guide the output shaft 17, and the upper end of the bearing guide 21 is attached to both upper and lower ends of an example of a torque detection mechanism having an elastic body. External bacterial serration section 16
A strain gauge tube 16 having a strain gauge tube 16a and a strain gauge tube 16b having a diameter of
b is configured to be positioned so as to mesh with the internal tooth serrations 20 and the internal tooth serration portions 19a of the bearing stand 19. A pair of strain gauges 22 are attached to the middle part of the strain gauge tube 16, and the lead wires of these strain gauges 22 are passed through the notches 16c provided in the strain gauge tube 16 to the notches 19b of the bearing stand 19. Guided, this bearing stand 1
It is configured to be taken out to the outside via a connector 23 fixed to the end of the connector 9.

In the above automatic screw tightening machine with torque sensor,
Even if the motor main body 12 is pulled when binding the motor lead wires to the base or the bracket 2 before starting the screw tightening work, the motor main body 12 is fixed to the driver base 4. The motor body 12 does not rotate. Moreover, when the motor is driven in this state, the motor main body 12 vibrates, but since the motor main body 12 is fixed to the driver stand 4 via the support 11, not only does it receive no force in the rotational direction, but the motor main body 12 and the storage case 14 to which the strain gauge tube 16 is fixed are separated.
is not subjected to any vertical force due to the vibration of the motor body 12, and the torque value before the start of work can reliably display the zero point.

When the work starts, the cylinder 5 operates, the driver stand 4 and the chuck stand 6 move together, and after the chuck stand 6 stops at a predetermined position, the driver stand 4
moves independently. Therefore, driver bit 1
0 penetrates inside the chuck body 9 and connects to the chuck claw 9a.
Tighten the screw held in place on the workpiece (not shown). At this time, since the driver bit 10 at the start of screw tightening has an arbitrary rotation speed using a group of reduction gears, the screw tightening work can be performed quickly.

Thereafter, as the screw is tightened to the workpiece, the reaction force applied to the driver bit 10 is transmitted to the reduction gear group via the output shaft 17, and further via the reduction gear group to the storage case 14 that stores and holds it. The storage case 14 rotates between the driver stand 4 and the motor body 12. This rotation of the storage case 14 causes the upper end of the strain gauge tube 16, one end of which is locked, to rotate, and the amount of strain is detected by the strain gauge 22 attached thereto.

In the embodiment, a strain gauge tube is used as the torque detection mechanism, but as shown in FIGS. 3 and 4, the rotation of the storage case 14 is controlled by the locking pin 3.
1a to the displacement of the leaf spring 31, and the position sensing device 32 may be used to detect this displacement. This position sensing device 32 has a light emitting element 33 attached to move together with the leaf spring 31, and a light receiving element 34 fixed correspondingly to the light emitting element 33. The displacement amount of the leaf spring 31 is detected by detecting the position of the light emitting element 33 . Further, in the embodiment, a group of reduction gears is used as the reduction mechanism, but the same effect can be obtained even if a continuously variable transmission mechanism 35 as shown in FIG. 5 is used. This unauthorized reduction mechanism 35 has an input disk 37 of an operating planetary mechanism 36 connected to a drive shaft (not shown) of a motor in a storage case 14, and a circumference surrounding the axis of the input disk 37. A plurality of planet cones 38 are arranged on the top at predetermined intervals. The planetary cone 38 is formed with a conical surface 38a as a transmission surface, a flat surface 38b on the back surface of the conical surface 38a, and a circumferential groove 38c having a concave cross section located adjacent to the conical surface 38a. Further, the input disk 37 is placed in the circumferential groove 38c, and the input disk 37 is placed in the flat surface 38b.
A cam disk 39 rotating concentrically with the cam disk 7 is arranged so as to frictionally engage with the cam disk 39, and this cam disk 39 transmits its rotation to a driver bit (not shown) via a buffer mechanism 40 and a connecting mechanism 18. is configured to do so.

On the other hand, a speed change ring 41 is disposed on the outer periphery of the planetary cone 38 so as to be able to rotate and move along the conical surface 38a by frictionally engaging with the conical surface 38a. It is configured to be located on the high speed side. Moreover, one end of an arm 43 is rotatably locked to this speed change ring 41, and the other end of this arm 43 is fixed to an inner cylinder portion 44 and rotatably locked to a fixed ring 45. This arm 43 is configured to limit the amount of movement of the speed change ring 41 toward the high speed side.

Further, in the embodiment, the motor body is fixed by a support, but a cylindrical case may also be used.

Effects of the Invention As explained above, the present invention fixes the motor body to the driver stand via a support, rotatably holds the storage case that houses the reduction mechanism that rotates in response to the rotation of the drive shaft, This is because the rotational torque of the storage case is detected by a torque detection mechanism, and the rotational torque when the storage case rotates in response to the reaction force applied to the driver bit is detected as the torque value applied to the driver bit. By bundling the motor lead wires, the torque detection mechanism will not be affected even if the motor body is pulled, and the torque value can be displayed at the zero point before starting work, resulting in highly reliable torque detection. There are advantages such as making it possible to In addition, since the present invention does not use a planetary gear mechanism for the reduction mechanism, the driver bit can be rotated at any rotation speed when starting screw tightening, which has the advantage of allowing quick screw tightening work. be.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts of the present invention, Fig. 2 is an overall explanatory diagram of the invention, Fig. 3 is a sectional view of the main parts showing another embodiment of the torque detection mechanism according to the invention, and Fig. 4 is a sectional view of the main parts of the present invention. FIG. 3 is a sectional view of the main part taken along the line A-A in FIG. 3, FIG. 5 is a sectional view of the main part showing another embodiment of the speed reduction mechanism according to the present invention, and FIGS. It is a sectional view of the main part. 1... Automatic screw tightening machine with torque sensor, 2...
Bracket, 3...Guide shaft, 4...Driver stand, 5...Cylinder, 6...Chuck stand, 7
...Spring, 8...Hose, 9...Chuck body,
9a...chuck claw, 10...driver bit,
11...Support, 12...Motor body, 13...
... Drive shaft, 13a ... Fitting hole, 14 ... Storage case, 14a ... Upper case, 14b ... Lower case, 15 ... Input shaft, 16 ... Strain gauge tube, 16a, 16b ... External tooth serration part, 1
6c...Notch, 17...Output shaft, 18...Connection mechanism, 18a...Universal joint, 18b
... Length adjustment mechanism, 19 ... Bearing stand, 19a ...
Internal tooth serration part, 19b...notch, 20...
Internal tooth serration, 21...Bearing guide, 22...
... Strain gauge, 23 ... Connector, 31 ... Leaf spring, 31a ... Locking pin, 32 ... Position sensing device, 33 ... Light emitting element, 34 ...
Light receiving element, 35... Constantly variable speed mechanism, 36... Differential planetary mechanism, 37... Input disk, 38... Planetary cone, 38a... Conical surface, 38b... Flat surface, 38
c...Circumferential groove, 39...Cam disc, 40...
Buffer mechanism, 41... Speed change ring, 42... Adjustment spring, 43... Arm, 44... Inner cylinder portion, 45...
Fixed ring, 51... Planetary gear mechanism, 51a...
internal gear.

Claims (1)

[Claims for Utility Model Registration] The driver stand 4 can be moved up and down by the operation of the cylinder 5, and a motor main body 12 of a motor that moves together with the driver stand 4 is attached to the upper part of the driver stand 4, and the drive shaft 13 of this motor is attached to the upper part of the driver stand 4. The input shaft 15 of the reduction mechanism housed in the storage case 14 is connected to the storage case 14, and the driver bit is further connected to the output shaft 17 of the reduction mechanism via the connection mechanism 18. The case 14 is arranged rotatably on the driver stand 4, and a torque detection mechanism having an elastic body with one end of the storage case 14 locked is fixed to the driver stand 4, and rotates in response to the reaction force of the driver bit. In an automatic screw tightening machine with a torque sensor configured to detect the torque applied to the driver bit from the amount of rotation of the storage case 14, the motor body 12 is fixed to the driver stand 4 via the support 11, while the motor body 12 and A storage case 14 is rotatably arranged between the driver stand 4 and the motor main body 12, and the input shaft 15 stored in the storage case 14 is arranged to fit onto the drive shaft of the motor main body 12. An automatic screw tightening machine with a torque sensor.