JPH0911068A - Thread fastening device - Google Patents

Abstract

PURPOSE: To restart the operation of a thread fastening device at a point of time when a new toque sensor is replaced with a failed torque sensor by provid ing the torque sensor with a controlling means for controlling the magnitude of torque in a pseudo torque circuit. CONSTITUTION: In the case of repeatedly conducting thread fastening work, when testing whether a torque sensor 6 is good or not, if the torque sensor 6 is repeatedly discriminated to be bad, the torque sensor 6 is decided to be failured and a new good torque sensor is replaced with the torque sensor 6. In this case, a control means 31 is previously adjusted to match the torque sensor 6, so that the torque sensor 6 is simply changed and a new torque sensor is just connected to a controller B in the same manner as before to be put in the state of being normally tested to see whether it is good or bad. Accordingly, it is possible to immediately bring a thread fastening device to the normal operating condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening device used for tightening screws such as bolts and nuts.

[0002]

2. Description of the Related Art As shown in FIG. 5, a screw tightening device comprises a screw tightening machine A used at a place for screw tightening work and a controller B installed at a position, for example, about 5 m away from the screw tightening machine. The screw tightener A is composed of members indicated by reference numerals 2 to 7, and is used by being mounted on the base frame 1 that moves up and down. 2 is a motor for generating screw tightening force,
3 is a speed reducer connected to the motor 2 to increase the screw tightening force, 4 is an output shaft of the speed reducer 3, and 5 is a fitting member for transmitting turning force to the screw 8 to be tightened, which is a socket. As an example, it is attached to the tip of the output shaft 4. The fitting member 4
Is used according to the shape of the fitting portion provided on the head of the screw 8. Reference numeral 6 is a torque sensor for outputting a torque signal corresponding to the magnitude of the torque applied to the fitting member 5, and is connected to the fitting member 5 so that the torque is applied to the torque sensor 6. . For example, the base frame 1 so that the torque is applied to the torque sensor 6 as described later.
And the speed reducer 3 are interposed. Reference numeral 7 denotes a connector for electrical connection in the torque sensor 6. On the other hand, the controller B is provided inside the casing 10 with circuits such as a drive circuit for the motor 2 and a torque measuring circuit described later. In addition, 11 is attached to the casing 10, 11 is a screw tightening command switch, 12 is an abnormality indicator, and 13, 14 and 15 are connectors for electrical connection. Reference numerals 17, 18, and 19 denote cables connecting the screw tightener A and the controller B, and the length thereof is, for example, 1
The length is 0 to 20 m, and a multi-core cable is used in each case.

In such a screw tightening device, when an electric current for operation is supplied from the controller B to the motor 2 with the base frame 1 lowered and the socket 5 fitted into the screw head of the screw 8, The motor 2 rotates, the socket 5 rotates via the speed reducer 3, and the screw 8 is tightened. At this time, the torque applied to the socket 5, that is, the screw tightening reaction force generated from the screw 8, is applied to the torque sensor 6 via the socket 5, the output shaft 4, the internal mechanism of the speed reducer 3, and the case of the speed reducer 3. The torque sensor 6 detects the reaction force and outputs a torque signal. The torque signal is given to the controller B. In the case of the above screw tightening, screw 8 up to the specified torque
Is tightened, the controller B discriminates it from the torque signal and stops the supply of current to the motor 2,
The screw tightening is completed.

The torque-related circuit in the torque sensor 6 and the controller B is constructed as shown in FIG. Reference numeral 20 in the torque sensor 6 indicates a torque detection circuit, which includes gauge resistors G1 to G4 for detecting a torque value attached to the frame 6a to which the reaction force is applied, and gain adjustment resistors RG1 and RG.
And 2. Reference numerals 21 to 24 denote connection terminals of the torque sensor 6, which are provided with four terminals and have the connector 7. 21 and 22 are a pair of power supply terminals, and 23 and 24 are a pair of output terminals. An example of the rating of the torque sensor 6 having such a configuration is that when the voltage applied to the power supply terminal is DC 10 V and the applied torque is 2500 kgcm, the output appearing at the output terminal is 10 mV.

Reference numeral 25 in the controller B is a torque measuring circuit, which includes a sensor power supply 26 (for example, a constant voltage power supply of DC 10V) for supplying power for operation to the torque sensor 6, an amplifier circuit 27, and a signal processing circuit 28. It consists of. Reference numeral 29 denotes a quality inspection unit of the torque sensor 6, which is composed of elements indicated by reference numerals 30 to 34 and 12. Reference numeral 30 denotes a pseudo torque circuit, which is for applying an adjustable torque to the torque sensor 6 in a pseudo manner by electrical means. Reference numeral 31 is an adjusting means for adjusting the magnitude of the pseudo-applied torque, and is for adjusting the magnitude of the pseudo-applying torque in correspondence with the torque sensor 6. The magnitude of the torque set by the adjusting means 31 is selected to be half the rating of the torque sensor 6, for example. The pseudo torque having the set magnitude is also referred to as an inspection torque in the present specification. As the adjusting means 31, for example, a variable resistor is used so that its adjustment is easy. Reference numeral 32 denotes a contact / separation switch for connecting and disconnecting the adjusting means 31 with respect to the torque detection circuit 20. Reference numeral 33 is a control circuit for controlling the operation of the switch 32 in response to a quality inspection command.
Reference numeral 34 is a discriminating circuit for discriminating whether or not the torque signal value output from the torque sensor 6 is proper when the pseudo torque is applied. Reference numerals 35 to 38 denote connection terminals with the torque sensor 6 in the controller B, which are provided with four terminals and have the connector 15. 35 and 36 are a pair of power output terminals, 37 and
38 is a torque signal input terminal. The connection cable 19 has four connection wires 39 corresponding to the number of terminals.

A series of control operations at the time of screw tightening work by the screw tightening device are as follows. When a command for screw tightening is given by the command switch 11, the quality inspection unit 29 determines whether the torque sensor 6 is good or not as follows. First, the pseudo torque circuit 30 applies a pseudo torque to the torque sensor 6 by electrical means. That is, the control circuit 33
Causes switch 32 to be temporarily closed. Then, while it is closed, the resistor 31 is connected in parallel with the series circuit of the resistors RG1 and G3. As a result, the torque detection circuit 20 becomes in the same state as when the torque of the same magnitude as the above-mentioned inspection torque is actually applied to the torque sensor 6, and the output terminal
A torque signal having a magnitude corresponding to the above inspection torque is output to 23 and 24. The torque signal is given to the controller B via the cable 19 and amplified by the amplifier circuit 27. When the discrimination circuit 34 receives the amplified signal and discriminates that the value of the torque signal is proper, the discrimination circuit 34 gives an operation command to a drive circuit (not shown) for driving the motor 2. On the other hand, if it is determined that the torque signal is not appropriate, the display 12 is operated to display that the torque sensor 6 is defective. When the quality determination is performed as described above and the operation command is given to the drive circuit of the motor 2, the current is supplied from the drive circuit to the motor 2 and the operation of the motor 2 is performed and the screw tightening is performed as described above. Be seen.

During screw tightening, the torque detection circuit 20 constantly outputs a torque signal corresponding to the torque applied to the torque sensor 6 to the output terminals 23 and 24. The torque signal is a cable
It is given to the controller B via 19 and amplified by the amplifier circuit 27. The signal processing circuit 28 receives the amplified signal. When the signal processing circuit 28 determines from the value of the signal that the torque applied to the torque sensor 6 has reached the preset tightening torque value, it gives a stop command to the drive circuit of the motor 2. As a result, the current supply to the motor 2 is stopped and the screw tightening is completed as described above. The above operation is repeated every time a screw tightening command is given by the switch 11.

According to the screw tightening device as described above, the screw tightening can be carried out very efficiently by utilizing the turning force of the motor, and in that case, the torque sensor 6 is used to fix the socket 5 as described above. The tightening torque can be made appropriate so that the screw 8 can be tightened to a predetermined torque. Furthermore, since the quality of the torque sensor 6 can be inspected by the quality inspection unit 29, the reliability of the torque tightened based on the torque sensor 6 can be made highly reliable. In addition, since the quality inspection is performed by applying a pseudo torque by an electric means, the quality inspection can be performed very quickly and easily, and the inspection can be performed with almost no time hindrance.

[0009]

However, the above-described conventional screw tightening device has the following problems. That is, when the torque sensor 6 fails, for example, it is replaced with a new one. When replaced, the adjustment means 31 in the pseudo torque circuit 30 needs to be adjusted. This is for the following reasons. The electrical value of the torque sensor 6 is different for each sensor. For example, the values of the resistors G1 to G4, RG1, and RG2 are different for each sensor. On the other hand, the quality check is performed by adjusting means 31.
Thus, a torque of a predetermined magnitude adjusted according to the torque sensor 6 is artificially applied to the torque sensor 6. Therefore, in a state where the new torque sensor 6 for replacement is simply connected to the controller B which has been continuously used since the old time, the new torque sensor 6 becomes inconsistent with the adjustment state of the adjusting means 31 in the old controller B. . Therefore, if the torque sensor 6 is simply replaced as described above, the discriminating circuit 34 discriminates a defect during the inspection by the quality inspection unit 29, and the screw tightening operation cannot be performed. For this reason, the adjusting means 31
Need adjustment. However, this adjustment must be carried out by calling a specialist engineer, and during that time, the operation of the screw tightening device must be stopped, which causes a problem of impairing productivity.

The screw tightening device of the present invention is provided in order to solve the above-mentioned problems (technical problems) of the prior art. The first purpose is to enable the screw tightening to be performed very efficiently by utilizing the turning force of the motor. The second purpose is to enable the tightening torque to be proper by using a torque sensor in the case of the screw tightening so that the screw can be tightened to a predetermined torque. A third object is to make it possible to perform a quality test of the torque sensor, thereby making it possible to increase the reliability of the magnitude of the torque tightened based on the torque sensor. A fourth object is to enable the quality inspection of the torque sensor to be quickly and easily performed by an electric means, thereby reducing the time that hinders the screw tightening work. A fifth object is to connect a new torque sensor when the torque sensor is replaced due to a failure of the torque sensor or other reasons, even if the quality inspection of the torque sensor can be electrically performed. From the point in time, the operation of the screw tightening device can be restarted immediately, and its productivity can be kept good. Other objects and advantages will be more readily apparent from the drawings and the following description associated therewith.

[0011]

In order to achieve the above object, the screw tightening device according to the present invention has a fitting member for transmitting a turning force to a screw to a motor for generating a screw tightening force. A torque sensor for outputting a torque signal corresponding to the magnitude of torque is connected to the fitting member so that the screw tightening force is transmitted to the fitting member. The torque sensor is connected so as to be applied thereto, and the torque sensor includes a pseudo torque circuit for pseudo applying an adjustable torque to the torque sensor by an electric means, and a pseudo torque circuit from the pseudo torque circuit to the torque sensor. In the screw tightening device that is connected to the determination circuit for determining whether the torque signal value output from the torque sensor is proper when the torque is applied to the pseudo torque circuit, That adjusting means for adjusting the magnitude of the torque is one which gave provided in the torque sensor.

[0012]

[Function] The screw can be tightened by rotating the fitting member by the screw tightening force generated by the motor. In this case, the torque sensor detects the torque applied to the fitting member. The screw can be tightened to a predetermined torque value by turning the motor until the detected torque reaches a predetermined value. The quality of the torque sensor can be determined by applying a pseudo torque to the torque sensor from the pseudo torque circuit and determining whether or not the torque signal value output from the torque sensor at that time is appropriate by the determination circuit. The adjusting means provided in the torque sensor can be adjusted in advance so as to match the torque sensor provided with the adjusting means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS. Since each member, configuration and operation indicated by the same reference numeral as used in the description of the above-mentioned prior art is the same as that of the above-mentioned prior art, the description will be duplicated.
The duplicate description will be omitted. FIG. 1 showing a first embodiment.
In the above, the adjusting means 31 is provided in the torque sensor 6 so that it can be handled integrally with the torque sensor 6.
For example, it is housed in the frame 6a, and one end and the other end are electrically connected to the power supply terminal 21 and the inspection terminal 41 in the connector 7. The resistance value of the adjusting means 31 is adjusted in advance so as to match the torque sensor 6 provided with the adjusting means 31. That is, the resistance G1 to
Since the values of G4, RG1, and RG2 are different for each torque sensor as described above, when the adjusting means 31 is connected to the torque sensor 6 as shown in FIG. When a predetermined operating power supply voltage (for example, 10 V) is applied to and the inspection terminal 41 and the output terminal 23 are short-circuited, a predetermined amount corresponding to the magnitude of the inspection torque is output between the output terminals 23 and 24. It is adjusted so that the torque signal of the value is output. This adjustment is performed by the manufacturer of the torque sensor 6, for example. As the connector 7, for example, a connector having 5 terminals is used in order to include the inspection terminal 41. On the other hand, the connector 15 in the controller B also uses a five-terminal connector 15 so as to have the inspection connection terminal 42 corresponding thereto, and the connection cable 19 also uses a five-core connector.

A series of control operations at the time of screw tightening work with the above-mentioned structure are as described in the above-mentioned prior art.

When it is repeatedly judged that the torque sensor 6 is defective during the quality inspection of the torque sensor 6 when the screw tightening work is repeated, it is judged that it is a failure, and the torque sensor 6 is detected. Replace with a new good product. In this case, since the adjusting means 31 is adjusted in advance so as to match the torque sensor 6 as described above, it is possible to simply replace the torque sensor 6 and connect it to the controller B as in the previous case. Then, the state where the quality inspection can be normally performed is set. Therefore, the screw tightening device can be immediately brought to the normal operating system.

Next, FIG. 2 shows a different embodiment of the present invention, in which the adjusting means 31 is provided in the torque sensor 6, while the adjusting means 31 is connected to or disconnected from the torque detection circuit 20 of the torque sensor 6. Controller B
The torque sensor 6 and the controller B can perform such control without separately providing a new terminal so that the number of terminals in them or the number of core wires of the connection cable is sufficient. The purpose of this is, for example, that the connectors 7 and 15 need to have four terminals as in the conventional ones, and that the connection cable 19 also have four cores. In the figure,
Reference numeral 44 denotes a contact / separation circuit for connecting and disconnecting the adjusting means 31 to and from the torque detection circuit 20 of the torque sensor 6 in accordance with an additional command given through the connection terminals 21 and 22 of the torque sensor 6. And a switch control circuit 46 for controlling the switch 45. As an example of the additional command, the contact / separation circuit 44 receives a signal that the voltage between the power supply terminals 21 and 22 rises from 0 V to a predetermined power supply voltage, and closes the contact / separation switch 45 for a certain time from that point. It has a property of opening the switch 45 after a lapse of a certain time. A commercially available delay relay can be used as the contact / separation circuit 44. Reference numeral 47 is a coil for controlling the operation of the contact / separation switch 45, and 48 is a control circuit for energizing the coil 47. In this example, the torque sensor 6 is provided with the entire pseudo torque circuit 30 including the adjusting means 31 and the contact / separation switch 45.

On the other hand, 51 provided in the controller B is an additional command switch for giving an additional command for connecting the adjusting means 31 to the torque detection circuit 20 to the contact / separation circuit 44.
As an additional command, the change of the voltage between the power supply output terminals 35 and 36 from 0 V to a predetermined power supply voltage is changed by the change of the switch 51 from the off state to the on state.
I am trying to give it to. Reference numeral 52 denotes a control circuit for the additional command switch, which receives the command of the quality inspection and turns off the switch 51 once and then turns it on again.

In the configuration described above, when a command for quality inspection is given to the control circuit 52, the additional command switch 51 is once turned off and then turned on again under the control of the control circuit 52. As a result, the additional command is given to the power output terminals 35 and 36. This additional command is a connection cable 19
Is given to the torque sensor 6. In the torque sensor 6, the contact / separation switch 45 of the contact / separation circuit 44 is temporarily closed by the above-mentioned additional command, and the adjusting means 31 causes the torque detecting circuit to operate.
Connected to 20. By this connection, the quality of the torque sensor 6 is determined as described above. Then, the switch 45 is opened to disconnect the adjusting means 31 from the torque detection circuit 20, and the torque sensor 6 is brought into a normal torque measurement state. It should be noted that parts that are functionally identical to or equivalent to those in the previous figure and will not be described in detail will be denoted by the same reference numerals and redundant description will be omitted. (Also, in the following figures and the like, the same reference numerals are given to omit the duplicated explanation in the same way.)

Next, FIG. 3 shows a different embodiment of the contact / separation circuit 44 included in the torque sensor 6. In order to improve durability and obtain a long life, the contact / separation switch 45 is replaced by a semiconductor switch. For example, it shows an example configured with analog switches. In the switch control circuit 46, the resistance R1
The circuit consisting of C1 and capacitor C1 is the analog switch 45 above.
Is a time constant circuit for temporarily closing, for example, 0.5 seconds, and D1 is a diode for shortening the discharge time of the capacitor C1.

Next, FIG. 4 shows another embodiment of the additional command switch provided in the controller B. In order to improve durability and obtain a long life, the additional command switch 51 is provided.
1 shows an example in which the semiconductor switch is constituted by a semiconductor switch such as a transistor.

[0021]

As described above, according to the present invention, when the screw is tightened, the screw can be tightened very efficiently by utilizing the turning force of the motor 2. And in that case,
Since the torque sensor 6 is provided, the torque sensor 6
Can be used to tighten the screw 8 to a predetermined torque. Further, since the torque sensor 6 can perform the quality inspection by using the pseudo torque circuit 30 and the discrimination circuit 34, the reliability of the magnitude of the torque tightened by relying on the torque sensor 6 can be enhanced. There is also. In addition, the quality test of the torque sensor 6 can be performed by applying a predetermined torque in a pseudo manner by an electric means and determining whether or not the torque signal value output at that time is appropriate. Is very quick and easy, and has an effect that it can be performed with almost no time hindrance to the screw tightening work. Further, in the present invention, since the torque sensor 6 is provided with the adjusting means 31 for adjusting the magnitude of the pseudo torque applied at the time of the quality inspection of the torque sensor 6, the adjusting means 31 is The feature is that it can be adjusted in advance so as to match the torque sensor 6 provided with it. This means that even if the quality inspection of the torque sensor 6 is electrically performed as described above, when the torque sensor 6 is replaced due to a failure of the torque sensor 6 or other reasons, a new torque sensor 6 is required. There is an effect that a normal pass / fail test of the torque sensor can be made possible from the time when the torque sensor is connected. As a result, the operation of the screw tightening device can be immediately restarted, and there is an advantage that the productivity can be kept good.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a torque sensor, a torque measuring circuit, and a pass / fail test unit in a screw tightening device.

2 is a circuit diagram similar to FIG. 1 showing a different embodiment.

FIG. 3 is a circuit diagram showing another embodiment of a contact / separation circuit provided in the torque sensor.

FIG. 4 is a circuit diagram showing another embodiment of the additional command switch provided in the controller.

FIG. 5 is a diagram showing an entire screw tightening device.

FIG. 6 is a circuit diagram showing a torque sensor, a torque measurement circuit, and a pass / fail test unit in a conventional screw tightening device.

[Explanation of symbols]

 2 Motor 5 Fitting member 6 Torque sensor 30 Pseudo torque circuit 31 Adjusting means

Claims (4)

[Claims] 1. A motor for generating a screw tightening force,
A fitting member for transmitting a turning force to a screw is connected so that the screw tightening force is transmitted to the fitting member, and a torque signal corresponding to the magnitude of torque is output to the fitting member. Of the torque sensor is connected so that the torque applied to the fitting member is applied to the torque sensor, and the torque sensor is pseudo for applying an adjustable torque to the torque sensor by electrical means. A screw connecting a torque circuit and a determination circuit for determining whether or not the torque signal value output from the torque sensor is proper when a pseudo torque is applied to the torque sensor from the pseudo torque circuit. In the tightening device, the torque sensor is provided with an adjusting means for adjusting the magnitude of the torque in the pseudo torque circuit. 2. The torque sensor is provided with a contact / separation circuit for connecting and disconnecting the adjusting means to and from a torque detection circuit provided in the torque sensor in response to an additional command. 1 screw tightening device. 3. The screw tightening device according to claim 2, wherein the switch for connecting and disconnecting in the contact / separation circuit is constituted by a semiconductor switch. 4. The screw tightening device according to claim 2, wherein an additional command switch for giving the additional command to the connection terminal of the torque sensor is provided, and the additional command switch is constituted by a semiconductor switch.