JPH0468108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses an electric motor or an air motor as a drive source to tighten screws through a clutch, and when the screw tightening torque reaches a certain value, the clutch operates to brake the motor. This invention relates to a screwdriver that stabilizes the tightening torque.

Conventional structure and its problems The structure of the torque detection clutch of a conventional screwdriver is, for example, as shown in FIGS. 1 and 2, in which the drive cam 1 and the driven column 2 engage with each other at their peaks to detect torque. When the screw is tightened to the desired torque as shown in Fig. 2, the driven cam 2 overcomes the pressing force of the torque spring 3 and moves in the direction of arrow A.
The spring seat 4 pushes the limit switch 5 to cut off the power circuit of the drive source motor (not shown) to obtain a constant tightening torque. Further, 6 is a torque adjustment handle screwed into the case 7. By rotating this torque adjustment handle 6, a plurality of pins 8 provided in contact with the end face of the handle 6 are pushed and pulled, thereby pushing and pulling the spring receiver 9 in the same manner, thereby changing the amount of compression deflection of the torque spring 3. By changing the pressing force of the driven cam 2, the desired torque was detected. However, with the above-mentioned configuration, when changing the tightening torque, it is necessary to manually adjust the rotation of the torque adjustment handle 6 each time. This method has the disadvantage that it takes time and effort to change the setup for changing the torque, resulting in poor work efficiency.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a screwdriver that efficiently controls switching between different values of tightening torque by deflecting a tightening torque setting torque spring by a desired amount using an external drive source. .

Structure of the Invention The present invention comprises a drive source, a bit that transmits tightening torque from the drive source to a screw, a camshaft provided between the drive source and the bit and having a cam ridge at one end.
The output shaft, which holds the bit at the tip, is rotatably connected to the output shaft and is slidable, and is pressed against the camshaft and placed opposite to it, and by changing this pressing force, the torque value transmitted from the drive source to the bit can be adjusted. A hammering that constitutes a clutch mechanism, a torque spring that presses the hammering against a camshaft, an external drive source that is connected to the outer box of the clutch mechanism, and an electric control unit that controls the operation of the drive source and the external drive source. The torque spring is configured to be deflected by a desired amount by operating an external drive source through operation of an electric control unit.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a schematic diagram of a screwdriver according to the first embodiment of the present invention. Reference numeral 10 denotes an electric screwdriver main body as a driving source, which is fixed to an upper slide block 12 via a bracket 11. A bit 14 is held at the tip of the output shaft 13 of the electric screwdriver 10. 15 is a bracket 1 fixed to the base 16 with an air cylinder.
7, and an upper slide block 12 is fixed to the intermediate portion of the piston rod 18. 19
is a slide shaft into which an upper slide block 12 is slidably fitted. Reference numeral 20 denotes a bit guide, and a catcher 21 for holding supplied screws is fixed at the lower end. A bit guide bracket 22 is fixed to a lower slide block 23 which is slidably fitted to the slide shaft 19. Further, the lower slide block 23 is fixed to the lower end of the piston rod 18 of the air cylinder 15. A spring 24 is provided on the piston rod 18 between the upper slide block 12 and the lower slide block 23.
is always biased downward. A bracket 25 supports the slide shaft 19 and is fixed to the base 16. 26 is a lower limit stopper for the upper slide block 12, and 27 is a lower limit stopper for the lower slide block 2.
This is the lower limit stopper of No. 3. 28 is a support that supports the base and supports the entire device. Next, the main parts of the electric screwdriver main body 10 will be explained with reference to FIG. Reference numeral 29 denotes an electric motor as a driving source, and a reduction gear section 30 is connected to its output end. A camshaft 32 is fixed to the final reduction shaft 31. A cam crest 33 is formed on the end surface of the camshaft 32, and a steel ball 34 is pressed against this by a torque spring 38 via a spring seat 35, a thrust bearing 36, and a hammer ring 37. The state is shown in FIG. One end of the torque spring 38 is connected to the spring receiver 3
It is in contact with 9. Hammer ring 37 is output shaft 1
Although the groove 13 slides on the outer periphery of the output shaft 13 and the inner axial direction of the hammer ring 37,
-a, 37-a, the output shaft 13 and the hammer ring 37 rotate together, being restrained in the rotational direction by the balls 40 inserted into the shafts 37-a and 37-a. 41 is a pin that passes through the hammer ring 37 and a rod 42 that is inserted into the center hole of the inner diameter of the output shaft 13, and is prevented from coming off by a retaining ring 43. The output shaft 13 has a ball bearing 4 inserted into a clutch case 44 screwed into the gear part 30.
A thrust force is generated by a retaining ring 46 supported by 5-a and 45-b and fixed to the output shaft 13, a collar 47 between ball bearings 45-a and 45-b, and a retaining ring 48 fixed to the inner diameter of the clutch case 44. It is structured to receive One end of a switch rod 50 passing through the shaft 49 of the motor 29 abuts the rod 42, and the other end abuts one end of a differential pin 51. The other end of the differential pin 51 is in contact with a detection lever 53 of a limit switch 52. The differential pin 51 is slidably supported at the center of a guide 56 fixed to a partition plate 55 fixed to an exterior cover 54, and acts to constantly push back the switch rod 50 by a spring 57. Numeral 58 is a pin inserted into a plurality of holes in the clutch case 44, and is pressed by an adjuster plate 59 that is slidably fitted to the outer diameter of the tip of the clutch case 44, and controls the amount of deflection of the torque spring 38 via the spring receiver 39. Be variable. Reference numeral 60 denotes an air cylinder, and an adjuster plate 59 is fixed to the tip of a rod 61 with nuts 62-a and 62-b. The bolt 63 is a stopper for the adjuster plate 59, and by changing the amount of screwing into the bracket 11, the movement stroke of the air cylinder 60, that is, the movement stroke of the adjuster plate 59, is changed, and the amount of deflection of the torque spring 38 is set to the desired amount. can do. 64 is a tail cover that is fitted and fixed to the exterior cover, and there is an electric control unit (not shown) that controls the operation of the motor 29, the limit switch 52, the electric motor 29 that is the drive source 29, the air cylinder 60 that is the external drive source, etc. A receptacle 65 to which a power supply is connected is fixed. A ball bearing 66 is fitted into the clutch case 44, and its inner ring supports the reduction shaft.

The operation of the screwdriver configured as described above will be explained below.

First, when the piston rod 18 of the air cylinder 15 descends while the electric motor 29 is rotating, the upper slide block 12 fixed to its intermediate portion also begins to descend, and the electric screwdriver main body 10 also descends via the bracket 11. Further, since the lower slide block 23 is also urged downward by the spring 24, it descends at the same time, and the bit guide bracket 22, bit guide 20, and catcher 21 also descend. The screw previously held in the catcher 21 reaches the fastener, and the rotational force of the motor 29 is transmitted through the gear section 30, camshaft 32, steel ball 34, hammering 37, output shaft 13, and bit 14. It is transmitted to the screw and tightened by the fastener.

Next, when the screw is tightened to the initially set torque, that is, the adjuster plate 59 compresses the torque spring 38 via the pin 58 and the spring receiver 39, and the screw is tightened to the set torque, the bit 14, output shaft 13, and hammer ring 37 stop. However, since the motor 29 continues to rotate, the steel ball 34 attempts to climb the cam mountain 33, and the steel ball 34 moves in the direction of the arrow X. (Figure 5)
At this time, the hammer ring 37 is pushed by the steel ball 34,
Further, the rod 42 connected to the hammer ring 37 via the pin 41 also moves in the direction of the arrow W. (4th
Figure) When the rod 42 moves, the switch rod 50 that is in contact with one end of the rod is pushed back by the spring 57, the differential pin 51 also moves, the detection lever 53 of the limit switch 52 becomes open, and the power supply connected to the motor 29 The circuit (not shown) is cut off and the motor 29 is stopped. When the steel ball 34 climbs up the cam mountain 33, it returns to its original state, but the momentary opening and closing action of the limit switch 52 causes the motor 29 to
As is known, it is possible to short-circuit the circuit of , perform dynamic braking, and instantly stop the motor 29 . The aforementioned set torque value is used as the first set torque to deflect the torque spring 38 by a desired amount via the spring receiver 39 and pin 58 at the position where the rod 61 of the air cylinder 60 comes out in the direction of arrow B as shown in FIG. An adjuster plate 59 is fixed at the tip of the rod 61 with nuts 62-a and 62-b. Further, as the second set torque, when the rod 61 is retracted in the direction of arrow C, the adjuster plate 59 is stopped by the bolt 63 at a position where the torque spring 38 is deflected by a desired amount. Therefore, two types of tightening torque can be switched and set by operating the air cylinder 60 by operating the electric control section as necessary.

As described above, according to this embodiment, the electric motor 29 as a drive source, the bit 14 that transmits the tightening torque from the motor 29 to the screw, and the motor 29
A camshaft 32 is provided between the bit 14 and the camshaft 32 and has a cam ridge 33 at one end, an output shaft 13 that holds the bit 14 at its tip, and is rotatably connected to the output shaft 13.
Slidably presses against the camshaft 32 via the steel ball 34,
A hammering 37 is provided facing each other and constitutes a clutch mechanism that changes the torque value transmitted from the motor 29 to the bit 14 by changing the pressing force.
Torque spring 38 that presses this hammer ring 37
and an air cylinder 6 that slides the adjuster plate 59 as necessary via the spring receiver 39 and pin 58 to rotate the torque spring 38 by a desired amount.
By providing 0, switching between two types of tightening torque values can be easily and instantaneously performed by operating the air cylinder 60.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is an enlarged view of the main parts of a screwdriver showing a second embodiment of the present invention. In the figure, 11 is a bracket, 13 is an output shaft, 32 is a camshaft, 34 is a steel ball, 35 is a spring seat, 36 is a thrust bearing, 37 is a hammer ring, 38 is a torque spring, 39 is a spring receiver, 58
is a pin, and the above structure is similar to that shown in FIG. The difference from the configuration shown in FIG. 4 is that a pulse motor 67, which is an external drive source, is fixed to the bracket 11, and a feed screw 69 whose one end is supported by a ball bearing 68 is provided at its output portion, and an adjuster plate is attached to the nut 70 side. 71 was provided.

Next, the operation will be explained. When the pulse motor 67 is rotated by operation of the electric control unit, the feed screw 69 is rotated, and the nut 70 slides, thereby sliding the adjuster plate 71 to a predetermined position. The torque spring 38 can be deflected by a desired amount via the pin 58 and the spring receiver 39.

As described above, by providing the feed screw 69 and the pulse motor 67 that deflect the torque spring 38 by a desired amount by sliding the adjuster plate 71 as necessary via the spring receiver 39 and the pin 58, the pulse motor 67 can be By controlling the rotation speed, the amount of deflection of the torque spring 38 can be set arbitrarily. That is, the tightening torque can be set arbitrarily.

In the second embodiment, 67 is a pulse motor, but it goes without saying that it may be a servo motor or the like.

Effects of the Invention As described above, the present invention includes a drive source, a bit that transmits tightening torque from the drive source to a screw,
A camshaft that is installed between the drive source and the bit and has a cam ridge at one end, an output shaft that holds the bit at the tip,
a hammering that is rotatably coupled to the output shaft and slidable and pressed against the camshaft and constitutes a clutch mechanism that changes the value of torque transmitted from the drive source to the bit by changing the pressing force; A torque spring that presses this hammering against the camshaft, an external drive source connected to the outer box of the clutch mechanism,
The device includes an electric control unit that controls the operation of the drive source and the external drive source, and is configured to deflect the torque spring by a desired amount by operating the external drive source by operating the electric control unit, and the external drive source By operating the screwdriver, you can easily and efficiently change and set the tightening torque, and you can use a single screwdriver to handle screw tightening work that requires several different tightening torques. It has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts of a conventional screwdriver, FIG. 2 is a cross-sectional view of the same with the driven cam in motion, and FIG. 4 is an enlarged cross-sectional view of the main part of FIG. 3, FIG. 5 is an enlarged plan view of a partial cross section of the camshaft portion, and FIG. 6 is an enlarged partial cross-sectional view of a screwdriver according to another embodiment of the present invention. FIG. 13... Output shaft, 14... Bit, 29... Motor, 32... Camshaft, 33... Cam mountain, 37...
...Hammering, 38...Torque spring, 39...
Spring receiver, 58... Pin, 59... Adjustment plate, 60... Air cylinder, 67... Pulse motor, 69... Feed screw, 70... Nut,
71...Adjust plate.

Claims (1)

[Claims] 1. A drive source, a bit that transmits tightening torque from the drive source to the screw, and a camshaft provided between the drive source and the bit and having a cam ridge at one end;
An output shaft that holds a bit at the tip thereof is rotatably connected to the output shaft, is slidable and presses against the camshaft, and is provided opposite to the camshaft, and by changing this pressing force, transmission from the drive source to the bit is achieved. a hammering that constitutes a clutch mechanism that changes a torque value; a torque spring that presses the hammering against the camshaft;
an external drive source connected to an outer box of the clutch mechanism; and an electric control unit for controlling the operation of the drive source and the external drive source, and the external drive source is operated by operation of the electric control unit. A screwdriver configured to deflect the torque spring by a desired amount by bending the torque spring.