JPS5927319B2 - Torque tightening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque tightening device, and more specifically, the present invention relates to a torque tightening device, and more specifically, it is capable of accurately tightening a tool to be tightened up to a high torque using power means, and is relatively simple in structure and inexpensive to manufacture. This invention relates to a torque tightening device.

Conventionally, torque tightening devices equipped with power means such as electric motors or hydraulic motors have been used for tasks that require high torque tightening, such as tightening bolts and nuts during vehicle assembly. In a tightening device, it is extremely difficult to accurately tighten a tool to be tightened with a predetermined torque.

For example, there is a method in which the amount of input to the power means (current, pneumatic pressure, oil pressure, etc.) is kept constant to obtain a constant output torque, but this method is difficult to adjust the amount of input to the output torque, and it is difficult to adjust the input amount to the output torque. It is difficult to obtain an output torque with stable accuracy because variations in the accuracy of the reduction gear device interposed between the means and the power shaft, that is, the tightening tool, affect the output torque. Furthermore, since this method does not release the output torque after it reaches a predetermined value, there are variations in accuracy due to the inertia of the power means. In addition, there is a method of installing a torque limiter on the output shaft to make it easier to obtain a constant output torque, but since torque limiters generally use friction, they have poor radial stability and are difficult to tighten with high torque. is not suitable. Furthermore, there is a method in which a torque detector is mounted on the power shaft and the detected torque is fed back to the input side to obtain a constant output torque, but this method is not suitable for rapid torque rise of the power shaft. Since a predetermined torque is detected and fed back to the input side, the response is poor and, as will be described later, there is a drawback that the output torque varies widely. This method also has the disadvantage that the entire device is expensive because it requires the use of expensive related equipment for feeding back the output torque to the input side. The present invention has been made to eliminate the above-mentioned conventional drawbacks, and for this reason, the torque tightening device according to the present invention connects a power shaft having a tightening tool at the tip to the motor output shaft, and A shaft is rotatably supported around the wheel D in a movable housing, and the movable housing is supported by a fixed support means so as to be rotatable around the power shaft, and the movable housing and the motor housing are integrated. The rotary torque of the movable housing in the anti-tightening direction is supported by a fixed hydraulic actuator, and the hydraulic actuator maintains internal pressure at a constant level from a hydraulic source via a relief valve. This makes it possible to support the rotational torque of the movable housing in the anti-tightening direction up to a certain level, and furthermore, when the movable housing or motor housing rotates in the anti-tightening direction, The present invention is characterized in that it includes a detection means for giving a drive stop command to the motor, thereby detecting a predetermined tightening torque on the output side and simultaneously releasing torque exceeding the predetermined tightening torque.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIGS. 1 and 2 show an embodiment of the present invention, and in the figures, reference numeral 1 indicates a motor operated by electric power, pneumatic pressure, hydraulic pressure, or the like.

A cylindrical movable housing 2 is integrally attached to the housing of the motor 1 on the output shaft side thereof. The movable housing 2 includes a bearing (not shown) that rotatably supports a power shaft 3 coaxially with the movable housing 2, and a reduction gear (not shown) that connects the output shaft of the motor 1 and the power shaft 3. (not shown) is built-in. A tightening tool 5 that can engage the head of the bolt 4 is integrally formed at the tip of the power shaft 3. The movable housing 2 is rotatably supported within a fixed housing 8 attached to a fixed base T via a pair of spaced apart bearings 6|6, so that it can rotate around the power shaft 3 together with the housing of the motor 1. It's getting old. An arm 9 extending in a substantially radial direction is integrally formed to protrude from the side of the distal end of the movable housing 2, and a piston 11 of a hydraulic piston cylinder 10 having a fixed cylinder portion is mounted below the distal end of the arm 9. The tips are engaged. The hydraulic piston cylinder 10 maintains the hydraulic pressure up to a certain level inside thereof, so that the tightening reaction force acting on the movable housing 2 can be supported up to a certain level via the piston 11 and the arm 9. It's getting old. That is, as shown in FIG. 2, a conduit 15 and a conduit including a check valve 16 are connected to the head side inlet 12 of the hydraulic piston cylinder 10 from the hydraulic pressure side outlet 14 of the pressure transmitter 13 that converts air pressure to hydraulic pressure. Hydraulic pressure is introduced through the IT and conduit 18, and the pressure side inlet 19 of the pressure transmitter 13 is provided with a two-position switching valve 21 which is normally spring-loaded to the position shown by a pneumatic pressure source 20. Conduit 22 containing
Air pressure is introduced through the The two-position switching valve 21 functions to switch between introducing and discharging air pressure from the air pressure source 20 to the pressure transmitter 13. Further, a conduit 24 including a check valve 23 is connected to the conduit 15 in parallel with the conduit IT including the check valve 16, and a conduit 18 is connected to the conduit 24 and the head side inlet 12 of the hydraulic piston cylinder 10. 2-position switching valves 25a, 2 which are normally pressed by a spring to the position shown in the figure.
5b, 25c... and relief valves 26a, 26b, 26
c... and a plurality of conduits 2Ta arranged and inserted in series,
2Tb, 2Tc... (only 2Ta and 2Tb are shown in the figure) are connected in parallel. Each of the above two-position switching valves 25a
, 25b, 25c, . . . have the same configuration, and each serves to switch between conducting and blocking fluid from the hydraulic piston cylinder 10 toward the pressure transmitter 13. Furthermore, each of the relief valves 26a, 26b, 26c, . Therefore, by selectively operating one of the two-position switching valves 25a, 25b, 25c, etc., the relief valve 26 corresponding to the selected two-position switching valve 25 is activated in the hydraulic piston cylinder 10. Therefore, the pressure determined up to a certain level is maintained, and thereby the tightening reaction force (in the direction of arrow B shown in the figure) up to a certain level acting on the movable housing 2 is supported via the piston 11 and the arm 9. I can do it. The limit switch 28 is engaged and pressed by an engagement piece 29 attached to the piston 11 of the hydraulic piston cylinder 10, thereby causing the piston 11 to move downward, that is, the movable housing 2
The rotation in the anti-tightening direction (arrow B in the figure) can be detected. The detection signal from the limit switch 28 is used to stop the operation of the motor 1. Next, to explain the operation of the torque tightening device having the above configuration, first, the tightening tool 5 at the tip of the power shaft 3 is engaged with the head of the bolt 4, and then the torque value required for tightening the bolt 4 is Accordingly, one of the two-position switching valves 25a, 25b, and 25c is selectively operated, and the two-position switching valve 21 is positioned as shown in FIG. 2 to introduce air pressure from the air pressure source 20 to the pressure transmitter 13.

As a result, hydraulic pressure is introduced into the hydraulic piston cylinder 10 from the pressure transmitter 13 via the check valve 16 and the conduit 17|18, and the selected two-position switching valve 25 is introduced into the hydraulic piston cylinder 10. A predetermined internal pressure determined by the relief valve 26 corresponding to the pressure is maintained, and the housing 10 is pressed with a predetermined force in the direction of tightening rotation of the power shaft 3 (arrow A in the figure) via the piston 11 and the arm 9. be done. At the same time, the limit switch 28 is engaged and pressed by the rising piston 11 via the engagement piece 29. At this point, the two-position switching valve 21 is switched to open the pneumatic side 19 of the pressure transmitter 13. The motor 1 is energized by the operation of the limit switch 28, the power shaft 3 is rotated, and the bolt 4 is tightened. At this time, as shown in FIG. 3, the output torque of the power shaft 3 increases rapidly after a certain period of time, and the movable housing 2 receives a tightening reaction force from the power shaft 3 through the reduction gear in the housing 2 and the motor 1. However, since the movable housing 2 is pressed by the piston 11 via the arm 9 in the tightening direction so as to be able to support the tightening reaction force up to a predetermined magnitude, it does not rotate in the anti-tightening direction. In this way, the tightening action of the bolt 4 progresses, and when the output torque of the power shaft 3 reaches the set torque Ts, the tightening reaction force acting on the movable housing 2 is maintained by the relief valve 26 on the piston 11. Overcoming the pressing force in the tightening direction, the movable housing 2 starts rotating in the anti-tightening direction while pushing the piston 11 downward by the arm 9. As a result, the internal pressure inside the hydraulic piston cylinder 10 is reduced to the relief valve 2.
The clamping reaction force released into the pressure transmitter 13 via the pressure transmitter 6 and acting on the movable housing 2 is maintained at a substantially constant magnitude. Therefore, the output torque exerted on the power shaft 3 is maintained at approximately the set torque Ts within the range of the torque variation ΔT caused by the relief valve 26. On the other hand, the limit switch 28 is activated simultaneously with the lowering of the piston, thereby stopping the operation of the motor 1. At this time, there is a time lag Δt between the activation of the limit switch 28 and the stoppage of the operation of the motor 1, and conventionally, the output torque of the power shaft increases as shown by the broken line a in FIG. 3 even during this time lag Δt. In order to continue, there is a large variation in the output torque due to △t △T'
However, in the present invention, after the output torque of the power shaft 3 reaches the set torque Ts, it is maintained at a substantially constant torque value as shown by the solid line b in FIG.
There is almost no influence from t. Therefore, highly accurate output torque can be obtained. 4 and 5 show a modification of the present invention, which is substantially the same as the previous embodiment, but differs in the following points.

That is, in the previous embodiment, the arm 9 is formed to protrude from the movable housing 2, and the piston 11 of the hydraulic piston cylinder 10 whose cylinder part is fixed to the lower end of the arm 9 is pressed into engagement with the piston 11. The coupling piece 29 is attached and engaged with the limit switch 28, but in this modification, instead of the above, a cylindrical cylinder 30 is fixed to the rear end of the movable housing 2 surrounding the motor 1. , an axial cylindrical hole 32 is provided in the center of the rear end wall 31 of the cylinder 30.
is provided, the housing part of the hydraulic rotary cylinder 34 is fixed on the fixed base 33, and the input side 35 of the hydraulic rotary cylinder 34 is fixed.
is connected to the conduit 18, the output shaft 36 of the hydraulic rotary cylinder 34 is inserted into the cylindrical hole n of the cylinder 30, the output shaft 36 and the cylindrical hole 32 are locked with a key, and the rear end of the cylinder 30 is connected to the conduit 18. A flange 37 is fixed around the flange 3T, and a limit switch 28 is pressed into engagement with a notch 38 of the flange 3T. With this configuration, after the output torque of the power shaft 3 reaches the set torque Ts, the movable housing 2 is allowed to rotate in the anti-tightening direction for a long time. The developed torque can be maintained at the set torque Ts for a long time. The operation of this modified example is substantially the same as that of the previous embodiment except for the points mentioned above, so a description thereof will be omitted.
Although the above-mentioned embodiments have all been described in connection with a tightening device in which the power shaft 3 can rotate in only one direction, the present invention can also be applied to a tightening device in which the power shaft 3 can rotate in both directions. It is possible.

In this case, an arm similar to the arm 9 in the embodiment shown in FIGS. 1 and 2 is attached to the movable housing 2.
They are provided at symmetrical positions with respect to the longitudinal axis of the housing (imaginary line C in FIG. 2), so that the hydraulic piston cylinder 10 can be selectively engaged with either one of these two arms depending on the direction of rotation of the power shaft 3. You can place it in The configuration from the hydraulic piston cylinder 10 to the air pressure source 20 can be used as is. As described above, according to the present invention, the predetermined tightening torque applied to the tool to be tightened is detected on the output side, and at the same time, the torque exceeding the predetermined tightening torque is released. The tightening torque does not vary significantly due to the inertia of the tightening torque, the time lag between detection of the predetermined tightening torque and stopping the operation of the power means, etc., and therefore, highly accurate output torque can be obtained.

In addition, the means for detecting a predetermined tightening torque and releasing the torque exceeding the predetermined tightening torque is composed of a hydraulic cylinder, a relief valve, a switching valve, etc., which have a relatively simple structure, so that the entire device is It can be manufactured at low cost. Furthermore, since a friction transmission device is not included between the power shaft and the motor output shaft, high torque tightening can be performed. Further, the output torque of the power shaft can be easily adjusted by adjusting the hydraulic pressure release capacity of the relief valve or by switching to a relief valve having a different hydraulic pressure release capacity. Furthermore, by making simple modifications, the present invention can also be applied to a torque tightening device in which the power shaft can rotate in both directions.

[Brief explanation of the drawing]

Fig. 1 is a partial side view showing an embodiment of the torque tightening device according to the present invention, with a part cut away, and Fig. 2 is a sectional view taken approximately along the line 3 is a diagram showing the torque characteristic curve of the torque tightening device according to the present invention in comparison with that of a conventional device, and FIG. 4 is a diagram similar to FIG. 1 showing a modification of the device of the present invention. 5 is a sectional view taken substantially along the line V--V in FIG. 4, and is similar to FIG. 2. 1... Motor, 2... Movable housing, 3... Power shaft, 4... Bolt, 5
......Tightening tool, 6...Bearing,
8... Fixed housing, 10... Hydraulic piston cylinder, 13... Pressure transmitter, 25
...2-position switching valve, 26...Relief valve, 28...Limit switch, 30...
...Cylinder, 34...Hydraulic pressure rotating cylinder, 3
6... Output shaft.

Claims (1)

[Claims] 1. A power shaft having a tightening tool at its tip is connected to the motor output shaft, and the power shaft is supported rotatably around the axis in a movable housing, and the movable housing is connected to the The movable housing is supported by fixed support means so as to be rotatable around a power shaft, the movable housing and the housing of the motor are integrally connected, and the rotational torque of the movable housing in the anti-tightening direction is supported by a fixed hydraulic actuator. The hydraulic actuator is configured such that the internal pressure is maintained at a constant level from a hydraulic source via a relief valve, and thereby the rotational torque of the movable housing in the anti-tightening direction is maintained at a constant level. What is claimed is: 1. A torque tightening device, which is capable of supporting up to a certain size, and further includes a detection means for giving a drive stop command to the motor when the movable housing or the motor housing rotates in the opposite tightening direction. 2. The hydraulic actuator comprises a hydraulic piston cylinder, and engages and presses a piston of the hydraulic piston cylinder toward a part of the movable housing or motor housing in a tightening direction, and also engages and presses a piston of the hydraulic piston cylinder in a tightening direction. The torque tightening device according to claim 1, wherein the torque tightening device is connected to a hydraulic pressure source via the relief valve. 3. The hydraulic actuator comprises a hydraulic rotary cylinder, the output shaft of the hydraulic rotary cylinder is axially engaged with the movable housing or the motor housing, and the input side of the hydraulic rotary cylinder is connected via the relief valve. A torque tightening device according to claim 1, which is connected to a hydraulic pressure source. 4. Claims 1 to 3, wherein the power shaft is rotatable in only one direction, and the hydraulic actuator is arranged so as to engage and press the movable housing or motor housing only in the one direction. Torque tightening device by either. 5. Claims 1 to 3, wherein the power shaft is rotatable in both directions, and the hydraulic actuator is arranged so as to be able to selectively engage and press the movable housing or motor housing in any direction. Torque tightening device by either. 6. A plurality of relief valves are provided in parallel between the hydraulic pressure source and the hydraulic actuating device, and each of the relief valves is capable of forming a different internal pressure in the hydraulic actuating device and is switchable. A torque tightening device according to any one of claims 1 to 5.