JPS59192468A - Clamping machine for bolt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is equipped with a transmission that changes the gear ratio by moving a slide gear, and uses an electromagnetic solenoid to switch between a high-speed, low-torque mode and a low-speed, high-torque mode. -Related to bolt tightening machines that tighten and loosen nuts.

(Prior Art) In order to improve work efficiency, it is sometimes preferable to tighten bolts and nuts at high speed and low torque when the bolts and nuts are seated on the washers, and at low speed and high torque after they are seated.

Therefore, bolt tightening machines that utilize a one-way clutch and a cam pawl or incorporate an automatic transmission mechanism in combination with a slip clutch have been proposed. However, such mechanical automatic transmissions have a problem in that they have a complicated structure and are inferior in durability.

Furthermore, in order to loosen bolts and nuts, it is required to be able to reverse the rotation, but with conventional automatic transmissions, reversing is difficult and the structure becomes extremely complicated. In particular, even when loosening (reversing), it is preferable to change gears during the tightening operation in order to improve work efficiency, but this is almost impossible with conventional automatic transmissions. (Objective of the Invention) The present invention was made in view of the above circumstances, and uses a gear type transmission with a simple mechanical structure and excellent durability.
A first object of the present invention is to provide a bolt tightening machine that can automatically change speed from a high speed, low torque mode to a low speed, high torque mode during forward rotation (tightening).

In addition, when reversing (loosening) the load, the load loosening torque (when it increases, it automatically goes into low-speed, high-torque mode; when the loosening torque decreases, it automatically goes into high-speed, low-torque mode. A second object is to provide a bolt tightening machine that can efficiently perform loosening work by switching between both modes even if bolts are attached.

(Structure of the Invention) In order to achieve the first object, the present invention transmits the rotation of a motor to an output shaft through a gear type transmission that switches between high speed, low torque mode and low speed, high torque mode by moving a slide gear. A bolt tightening machine that conveys the information, comprising an electromagnetic sealant and return spring that moves the slide gear, a lock detector that detects a locked state of the motor, and a comparator that detects that the motor current exceeds a set value, When the motor is in the forward rotation state, the motor is started in the high speed low torque mode, switched to the low speed high torque mode based on the output of the lock detector, and stops tightening based on the output of the comparator.

In order to achieve the second objective, a discrimination circuit is provided to detect when the motor current falls below a set value in the process of decreasing, in order to detect when to switch from low speed high torque mode to high speed low torque mode. , in a reverse rotation state, the motor is started in high speed low torque mode, switched to low speed high torque mode based on the output of the lock detector, and returned to high speed low torque mode based on the output of the discrimination circuit, repeating a series of operations. It is.

The present invention will be described in detail below based on the illustrated embodiments.

(Embodiment) FIG. 1 is a cross-sectional view (5) showing a transmission portion according to an embodiment of the present invention, and FIG. 2 is a circuit diagram thereof. Number 10 in Figure 1
1 is a subshaft of the transmission, and 12 is an output shaft. Rotation of a motor (not shown) is transmitted to the subshaft 10 via a gear 14 . A splined sliding gear 16 is slidably mounted on the output shaft 12. [Sliding gear] 6 includes high/low speed gears 16a, 16b, and by sliding, each gear L6a, 16b selectively meshes with the high/low speed gear 10a'+10b provided on the subshaft 10. . 18 is a slider that moves the slide gear 16, 20 is a return spring that returns the slide gear 16 to the high speed side, and 22 is an electromagnetic syringe that similarly moves the slide gear 16 to the low speed side. Move to low speed side. At the tip of the output shaft 12 there is a socket (
(not shown) are attached and detached. In this figure 1, slide gear 1
6, the low-speed, high-torque mode position is shown by a dotted line, and the high-speed, low-torque mode position is shown by a virtual line.

In Figure 2, THI and TH2 are thyristor stacks for high speed (6) and low speed, respectively, F and A are the field and rotor of a known series commutator motor (universal motor), and R is motor current detection. It is a resistance for use. SWI is a changeover switch for forward/reverse mode, and is interlocked with switch SW2. When this SWI is set to the normal rotation side and the starting switch SW3 is closed, the relay coil R1 is de-energized, so the field F is connected to the normal rotation side by the contacts R1a, R], b, and the A contact R1c is opened.

In this state, the coil SL of the solenoid 22 is de-energized, so the slide gear 16 is on the high-speed, low-torque mode side of the imaginary line in FIG. 1, and the motor is activated.

This rotation of the motor progresses the tightening of the bolts and nuts, and when the bolts and nuts are seated on the washers and the load is tightened, the torque increases and the motor current also increases. Motor current setting device VR
When the set value of I is reached, the output of the comparator C1 causes the phase control circuit F'C to suppress the motor current from becoming excessive. As the tightening progresses, if the load tightening torque further increases, the motor becomes locked. This locked state is detected by a lock detector comprising a comparator C2 that compares the output of the rotation detector R8 of the rotor A with the set value of the setting device VR2.

When the motor locks, the gate cutoff circuit G1 gate-controls THI to cut off the motor current, and relay coil R
2 is excited. Therefore, the A contact R2a is closed and the coil SL
is excited and the slide gear 16 moves to the low speed high torque mode. At this time, B contact R2b opens and A contact R2c closes, so TH2 operates instead of THI. This TH2 smoothly restarts the motor by means of a cushion start circuit C8 which is activated by the output of the gate cutoff circuit G.

Furthermore, the A contact R2d is also closed due to the excitation of the relay coil R2. Therefore, tightening progresses in this low speed high torque mode,
When the motor current reaches the setting value of the final tightening torque setter VR3, the comparator C3 causes the gate cutoff circuit G2 to cut off the motor current, and the tightening is completed.

The reversing (loosening) operation is performed as follows. When the changeover switch SWI is set to the reverse side, the relay coil R1 is excited, the field F is switched to the reverse side, and the A contact R1c is switched to the reverse side.
is closed and the slide gear 16 enters the low speed high torque mode.

Further, since the B contact R1d opens and the A contact R1e closes, TH2 is operated from then on.

Since SW2 also closes in the reverse direction in conjunction with SWI, the motor is smoothly started by CS and TH2.

Then, when the start switch sw3 is opened, the motor stops.

FIG. 3 is a circuit diagram of another embodiment. The structure and operation of this embodiment during normal rotation are the same as those of FIG. 2, but the structure and operation during reverse rotation are different. Therefore, the same parts as in FIG. 2 are denoted by the same reference numerals, and the description thereof will be repeated.Hereinafter, only the configuration and operation at the time of reverse rotation will be described.

When the selector switch SWI is set to the reverse side, the newly installed Rl
d is interlocked and enters the reverse direction and closes the start switch SW3, the slide gear 16 remains in the high speed low torque mode without moving and the motor starts. Melt nuts are only slightly tightened, so it takes a lot of torque to loosen them. As a result, the motor immediately locks, and A contacts R2a and R2b are opened by gate cutoff circuit Gl and relay R2.
, R2,c closes and changes to low speed (9) high torque mode, and A contact R2d also closes. In this state, when loosening progresses and the motor current decreases as the loosening torque decreases, a discrimination circuit that discriminates when the motor current falls excites relay coil R4. The determination circuit is configured to, for example, differentiate the output of a comparator that compares the motor current with a predetermined value, and determines whether the motor current has fallen below the predetermined value in the process of decreasing based on the sign or negative of the differential output. This coil R4 opens the B contact R4a, and the slide gear 16 returns to the high speed mode, and the B contact R4bX
TH2 is disconnected and THl is connected by disconnecting and connecting the A contact R4c. At this point, the motor again operates in high speed, low torque mode. Repeat the high speed and low speed modes as described above. As a result, even if dirt or rust forms on the bolt and the nut locks up during high-speed loosening, the system immediately switches to low-speed mode, allowing for efficient loosening work.

In the above embodiment, for convenience of explanation, circuits with similar functions are shown separately for high speed and low speed.
Of course, one circuit may be used for each mode (10). Furthermore, since the motor is started up gradually by the cushion start circuit in synchronization with the movement of the slide gear when switching modes, it is possible to help the slide gear to mesh correctly and to prevent damage to the teeth.

The lock detector may detect not only a complete lock state in which the motor stops, but also a drop in rotation to a predetermined speed, and the detected speed depends on the setting of the setting device VR2.

(Effects of the Invention) As described above, the present invention detects the motor lock and changes the sliding gear from the high speed, low torque mode to the low speed, high torque mode using a solenoid and a return spring, so the transmission is similar to the conventional one. The same effect can be obtained without using a complicated automatic transmission.

Therefore, the structure of the mechanical part is simpler and the durability is better than that of the conventional one.

In addition, during reverse rotation, the switching from low-speed mode to high-speed mode is determined based on the fact that the motor current has fallen below the set value during the decreasing process, and both modes are automatically switched while loosening the bolts. It is possible to perform the loosening work efficiently even when the above occurs.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a transmission according to one embodiment, and FIGS. 2 and 3 are circuit diagrams of different embodiments. 12... Output shaft, 16... Slide gear, 20. Return spring, 22... Electromagnetic solenoid, CI, C2. C3...Comparator, D...Discrimination circuit, C8...Cushion start circuit. Patent applicant Shibaura Seisakusho Co., Ltd. Agent Patent attorney Yama 1) Yudo Wen

Claims (4)

[Claims] (1) An electromagnetic plant gear that moves the slide gear in a bolt tightening machine that transmits the rotation of a motor to an output shaft through a gear type transmission that switches between high speed, low torque and low speed, high torque modes by moving the slide gear. and a return spring, a lock detector that detects a locked state of the motor, and a comparator that detects that the motor current exceeds a set value, and when the motor is in the normal rotation state, the motor is operated in the high speed low torque mode. A bolt tightening machine characterized by starting up, switching to a low speed high torque mode based on the output of a lock detector, and stopping tightening based on the output of a comparator. (2) The bolt tightening machine according to claim 1, wherein the motor is restarted smoothly by a soft start circuit in synchronization with switching between each mode. (3) An electromagnetic syringe that moves the slide gear in a bolt tightening machine that transmits the rotation of a motor to an output shaft through a gear type transmission that switches between high-speed, low-torque and low-speed, high-torque modes by moving the slide gear. and a return spring, a lock detector that detects the locked state of the motor, and a discrimination circuit that determines that the motor current becomes less than a set value in the process of decreasing the motor current, and when the motor is in the reverse rotation state, the high speed low torque A bolt tightening machine characterized by repeating a series of operations such as starting in a mode, switching to a low speed high torque mode based on the output of a lock detector, and returning to a high speed low torque mode based on the output of a discrimination circuit. (4) The bolt tightening machine according to claim 3, in which the motor is smoothly restarted via a soft start circuit in synchronization with each mode switching.