JPWO2008149454A1 - Rotation drive mechanism life test apparatus and method - Google Patents

Abstract

A weight (28) having a predetermined weight is connected to the rotation drive mechanism (4). Torque is applied to the rotation drive mechanism (4) by driving the rotation drive mechanism (4) and repeatedly rotating the weight (28). The life test of the rotational drive mechanism (4) is performed by repeating the application of torque.

Description

  The present invention relates to a life test apparatus and method, and more particularly to a life test apparatus and method for performing a life test by repeatedly applying a torque to a rotary drive mechanism.

  Screws are often used to assemble products and machine parts such as electrical and electronic devices. In order to perform screw tightening in the manufacturing process, a screw tightening device is used. The screw tightening device is generally called a screw tightening driver. The screw tightening driver has a rotary drive source such as an electric motor and a rotary drive mechanism for transmitting the rotational force (torque) of the rotary drive source to the driver bit.

  The rotational drive mechanism includes a gear train for transmitting rotational force, a bearing that rotatably supports the shaft of the gear, and the like. In the manufacturing process, since the screw tightening driver repeatedly performs the screw tightening operation, the gears and bearings of the rotary drive mechanism are required to have a life that can withstand a certain amount of repeated operation.

  The lifetime of the gears and bearings of the rotary drive mechanism can be estimated to some extent as individual components, but it is difficult to estimate the lifetime of a rotary drive mechanism configured by combining a large number of gears and bearings. Conventionally, when a failure occurs while actually using a screw tightening driver, the failed part is replaced or replaced with a new one.

  Thus, conventionally, a life test for determining the life of the entire screw tightening driver has not been performed, and therefore, it is not possible to specify a prior document disclosing a life test apparatus for a rotational drive mechanism such as a screw tightening driver. Can not.

  As described above, since the life test for determining the entire life of the screw tightening driver has not been performed in the past, the life of the screw tightening driver cannot be estimated, and the life of the screw tightening driver has expired until it fails. It was often used. However, if a screw tightening driver breaks down during the manufacturing process, the manufacturing process is interrupted and repaired, which causes a problem in production planning.

  A general object of the present invention is to provide a new and useful life test apparatus and method for a rotary drive mechanism that solves the above problems.

  A more specific object of the present invention is to provide a life test apparatus and method that can easily perform a life test of a rotary drive mechanism such as a screw tightening driver in a short time.

  According to one aspect of the present invention, there is provided a life test apparatus for a rotary drive mechanism, wherein the shaft is configured to be connectable to the rotary drive mechanism, the shaft is fixed, and is configured to be rotatable about the shaft. There is provided a life test apparatus for a rotary drive mechanism characterized by having a weight with a weight.

  According to another aspect of the present invention, there is provided a life test method for a rotary drive mechanism, wherein a weight of a predetermined weight is connected to the rotary drive mechanism, and the weight is repeatedly rotated by driving the rotary drive mechanism. By doing so, there is provided a life test method for a rotary drive mechanism, wherein torque is repeatedly applied to the rotary drive mechanism.

  Other objects, features and advantages of the present invention will become more apparent upon reading the following detailed description with reference to the accompanying drawings.

  According to the present invention, a life test of a rotary drive mechanism such as a screw tightening driver can be easily performed in a short time. Therefore, repair or replacement can be performed in advance before the life of the screw tightening driver comes to an end, and the problem that the manufacturing process work is interrupted due to a failure caused by the life of the screw tightening driver can be solved.

It is a perspective view which shows an example of the method for performing the lifetime test of a screw-fastening driver. 1 is a perspective view of a life test apparatus according to an embodiment of the present invention. It is a perspective view which shows the state which attached the screw tightening driver to the life test apparatus shown in FIG. It is a wave form diagram which shows the produced | generated torque, the rotational speed of a motor, and the vertical movement of an axis | shaft.

Explanation of symbols

2 Screw tightening driver 4 Rotation drive mechanism 6 Motor 6a Power supply line 8 Bit 10 Lever 12 Air cylinder 12a Output rod 20 Frame 20a Bottom plate 20b Rear plate 20c Top plate 20d Screw hole 22 Air cylinder 24 Moving base 26 Linear guide 26a Rail 26b Slider 28 Inertia 28a Upper surface 30 Axis 32 Display device

  Embodiments of the present invention will be described with reference to the drawings.

  In the following description, an example will be described in which a screw tightening driver drive mechanism is used as a rotation drive mechanism for performing a life test.

  FIG. 1 is a perspective view illustrating an example of a method for performing a life test of a screw tightening driver. In FIG. 1, the screw tightening driver 2 has a rotation drive mechanism 4 and an electric motor 6 as a drive source. By driving the motor 6, the rotational force of the motor 6 is transmitted to the rotation drive mechanism 4, and the bit 8 attached to the rotation drive mechanism 4 rotates. Thereby, the screw connected to the tip of the bit 8 can be rotated.

The rotational drive mechanism 4 has a plurality of gears for transmitting the rotational force of the motor 6, and a shaft and a bearing for rotatably supporting the gears. Torque is applied to these gears every time the screw tightening driver 2 is driven, and the gears are gradually worn. Also, shafts and bearings wear gradually. When such wear increases, the rotational drive mechanism 4 cannot perform normal operation and has a lifetime.
On the output shaft of the screw tightening driver 2, a bit 8 that rotates by transmitting torque to the recess of the screw head and the meshing screw is detachably held.
When the screw is tightened, since the screw is fed, the output shaft is pressed by a spring so that the bit 8 and the recess are not disengaged. In this way, the output shaft simultaneously performs rotation and two-axis motion of the shaft slide.

  In order to perform a life test of the screw tightening driver 2 configured as described above, in the example shown in FIG. The lever 10 is mounted so as to extend perpendicular to the longitudinal axis of the bit 8. And the air cylinder 12 is arrange | positioned in the vicinity of the lever 10 so that the lever 10 can be pressed. That is, the air cylinder 12 is disposed so that the output rod 12 a of the air cylinder 12 contacts the side surface of the lever 10.

  Here, when performing the life test of the rotational drive mechanism 4 of the screw tightening driver 2, it is necessary to fix the rotating shaft of the motor 6 so that it cannot rotate. When the lever 10 is pressed by the output rod 12a of the air cylinder 12 with the rotating shaft of the motor 6 fixed, the bit 8 tries to rotate. However, since the bit 8 is connected to the rotating shaft of the motor 6 via the rotation driving mechanism 4, the bit 8 cannot rotate and torque is applied to the bit 8. This torque is transmitted to the gear of the rotational drive mechanism 4. Therefore, by repeatedly pressing the lever 10 with the output rod 12a of the air cylinder 12, a predetermined torque (torque at the time of screw tightening) can be repeatedly transmitted to each part of the rotation drive mechanism 4, and the life test of the rotation drive mechanism 4 is performed. It can be performed.

  In the test method described above, the gear in the rotation drive mechanism 4 does not actually rotate, and the meshing position between the gears does not change. Therefore, torque is always applied to the gear at the same meshing position. Further, the relative position of the shaft and the bearing does not change, and torque is always applied at the same position. However, in actual use, the bit 8 rotates to rotate the screw, and the gear of the rotational drive mechanism 4 also rotates. When the screw is tightened, the rotation stops, and the maximum torque is applied here.

  Therefore, in the life test method as shown in FIG. 1, the torque of the gear of the rotational drive mechanism 4 is repeatedly applied at the same meshing position, which is different from the actual condition. That is, since torque is repeatedly applied at the same meshing position of the gear, only a part of the gear is worn, and there is a possibility that the actual life is shortened. In actual use, since the maximum torque is applied at a position where the gear stops after rotating (arbitrary position), the entire gear should be worn evenly.

  In order to eliminate such inconvenience, the life test apparatus according to one embodiment of the present invention has a configuration as shown in FIG. FIG. 2 is a perspective view of a life test apparatus according to an embodiment of the present invention.

  The life test apparatus shown in FIG. 2 has a frame (frame body) 20 formed of a rigid plate material such as a steel plate. An air cylinder 22 is attached to the bottom plate 20 a of the frame 20. A moving table (support member) 24 is attached to the output shaft of the air cylinder 22, and the moving table (support member) 24 can move in the vertical direction as the output shaft of the air cylinder 22 moves. In order to guide the vertical movement of the movable table 24, a linear guide 26 is provided.

  The rail 26 a of the linear guide 26 is fixed to the rear plate 20 b of the frame 20. The slider 26 b that moves along the rail 26 a is fixed to the side surface of the moving table 24. Thus, when the air cylinder 22 is driven and its output shaft moves in the vertical direction, the moving base 24 moves in the vertical direction while being guided by the linear guide 26.

  A shaft 30 is rotatably supported by a bearing on the upper part of the moving table 24, and an inertia 28 that functions as a columnar weight is attached to the shaft 30. The shaft 30 on the upper surface 28a side of the inertia 28 is processed into the same shape as the shape of the bit 8 attached to the screw tightening driver 2 and used. Therefore, the shaft 30 can be attached to the rotational drive mechanism 4 of the screw tightening driver 2 similarly to the bit 8.

  The upper plate 20c of the frame 20 is provided with a portion to which the screw tightening driver 2 is attached. Specifically, a screw hole 20d for fixing the screw tightening driver 2 with a bolt is provided in the upper plate 20c.

  FIG. 3 is a perspective view showing a state in which the screw tightening driver 2 is attached to the life test apparatus shown in FIG.

  When the screw tightening driver 2 is attached to the frame 20, the shaft 30 extending vertically upward from the inertia 28 is in a state of being attached to the rotational drive mechanism 4 of the screw tightening driver 2. Thereby, the inertia 28 is connected to the rotation drive mechanism 4, and when the screw tightening driver 2 is operated, the rotational force of the motor 6 is transmitted to the inertia 28 via the rotation drive mechanism 4 and the shaft 30, and the inertia 28 rotates.

  The inertia is made of a heavy material such as metal, and a large inertial force acts when rotating. A rotational torque is applied to the shaft 30 by this inertial force. In other words, if the size of the inertia 28 is appropriately determined, a desired torque can be applied to the shaft 30 when the inertia 28 is rotationally accelerated, and the motor 6 of the screw tightening driver 2 is driven. Occurs every time. Therefore, by intermittently driving the motor 6 of the screw tightening driver 2, a predetermined magnitude of torque can be repeatedly applied to the rotary drive mechanism 4 via the shaft 30. This corresponds to a state in which the screw is continuously tightened by the screw tightening driver 2.

  When the torque is generated using the inertia force of the inertia 28 (weight) as in the present embodiment, the motor 6 is driven in the same manner as in actual screw tightening, and therefore the same load as that in actual screw tightening is applied to the motor 6. Can be added to. For this reason, not only the test of the rotation drive mechanism 4 but also the repeated drive life test of the motor 6 can be simultaneously performed by performing the test with the life test apparatus according to the present embodiment. That is, the life test of the rotary drive mechanism 4 including the motor 6 can be performed.

  The magnitude of the inertia 28 can be determined based on the magnitude of the torque to be generated. When the inertia moment of the inertia 28 is represented by J and the angular acceleration at the time of rotating the inertia 28 is represented by ω / t, the torque T generated when the inertia 28 is rotated can be calculated by the following equation.

T = Jω / t (1)
Since the inertia moment J of the cylinder inertia 28 is proportional to the square of the diameter D of the cylinder, the above equation (1) is as follows.

T = 1/8 * mD ² ω / t (2)
Here, the angular acceleration ω / t is a value determined by the characteristics of the motor 6, and m is the mass of the cylinder. The torque T can be calculated using Equation (2). If the desired torque T and the angular acceleration of rotation by the motor 6 are known, the magnitude required for the inertia 28 can be calculated. Moreover, what is necessary is just to change the magnitude | size of the inertia 28, when changing the torque T which should be generated.

  The inertia 28 can be changed by replacing the inertia 28 with a different size. In this case, it is preferable to provide an attachment structure that allows the inertia 28 to be easily detached from the movable table 24. Alternatively, another weight may be attached to the outer periphery of the inertia 28. By providing an attachment portion such as a screw hole in the inertia 28, an additional weight can be easily attached or detached. In this case, it is preferable that the additional weight is attached so as to be point-symmetric with respect to the rotation axis of the inertia 28 so that the load is offset when the inertia 28 rotates.

  The shape of the inertia 28 is not limited to a cylindrical shape, and various shapes can be used. However, it is preferable that the inertia 28 has a point-symmetric shape with respect to the rotation axis so as not to apply an uneven load due to the rotation.

  In the life test apparatus according to the present embodiment, the movable table 24 can be moved in the vertical direction as described above. That is, by driving the air cylinder 22, the inertia 28 can be rotated and reciprocated in the vertical direction at the same time. This operation is the same as the operation of pressing the bit 8 against the screw head during actual screw tightening, and the life test of the spring in the rotary drive mechanism 4 can be performed at the same time. In addition, a load acting at the time of actual screw tightening can also be applied to the shaft, bearing and gear in the rotary drive mechanism 4, and the life test can be performed closer to the actual screw tightening conditions.

  As shown in FIG. 3, a display device 32 that detects a current flowing through the motor 6 of the screw tightening driver 2 and displays it as a torque value can be connected to the power supply line 6 a of the motor 6. Since the current value for driving the motor 6 of the screw tightening driver 2 is proportional to the generated torque, the generated torque can be obtained by detecting the current value supplied to the motor 6. The display device 32 can display the waveform of the torque that is actually generated. Further, the number of repetitions can be obtained and displayed by counting the peak of the generated torque. Further, by observing the torque waveform, it is also possible to determine that the service life is when the torque waveform deviates from the normal torque waveform. Or it can also be judged that it is a lifetime when the input current to the motor 6 exceeds a certain value.

  Next, a life test method performed by the life test apparatus according to this embodiment will be described.

  First, in the life test apparatus shown in FIG. 2, the inertia 28 is set so that a desired torque is generated. Next, as shown in FIG. 3, the screw tightening driver 2 is attached to the life test apparatus while the shaft 30 of the inertia 28 is connected to the rotation drive mechanism 4 of the screw tightening driver 2. That is, by attaching the screw tightening driver 2, the shaft 30 of the inertia 28 is connected to the rotation drive mechanism 4 of the screw tightening driver 2, and by driving the motor 6, the inertia 28 rotates.

  FIG. 4 is a waveform diagram showing the generated torque, the rotational speed of the motor 6, and the vertical movement of the inertia 28 (shaft 30) in the life test method described below.

  When the screw driver 2 is attached to the life test apparatus, the life test is started. When starting the life test, the air cylinder 22 is driven to keep the inertia 28 in the lowered position. This state is the same as the state where the bit 8 attached to the screw tightening driver is lowered by the spring. In this state, the motor 6 is rotated forward to rotate the inertia 28 in the screw tightening direction to generate a predetermined torque. The forward rotation of the motor 6 is to rotate the motor 6 so that the shaft 30 rotates in the direction in which the screw is tightened. When a predetermined torque is generated, the driving of the motor 6 is stopped. The inertia 28 continues to rotate due to inertia, but the rotational speed gradually decreases and stops.

  While the inertia 28 is rotating by inertia, the air cylinder 22 is driven to raise the inertia 28 once. As a result, the shaft 30 is also raised, and the thrust load acting on the rotary drive mechanism 4 becomes equal to the initial screw tightening state with the bit 8 raised. Then, before the rotation of the inertia 28 stops, the air cylinder 22 is driven to lower the inertia 28.

  When the rotation of the inertia 28 is stopped, the motor 6 is rotated in the reverse direction, and the inertia 28 is rotated in the reverse direction to generate torque in the opposite direction. The reverse rotation of the motor 6 is to rotate the motor 6 so that the shaft 30 rotates in the direction of loosening the screw. When a predetermined torque is generated, the driving of the motor 6 is stopped. The inertia 28 continues to reversely rotate due to inertia, but the rotational speed gradually decreases and stops.

  While the inertia 28 is rotating in the reverse direction due to inertia, the air cylinder 22 is driven to raise the inertia 28 once. As a result, the shaft 30 is also raised, and the thrust load acting on the rotary drive mechanism 4 becomes equal to the state in which the screw 8 has been removed with the bit 8 raised. Then, before the rotation of the inertia 28 stops, the air cylinder 22 is driven to lower the inertia 28.

  With the above operation, torque can be applied to the rotational drive mechanism 4 under substantially the same conditions as actual screw tightening and screw loosening, and a life test can be performed by repeating this operation. In the above-described example, the screw tightening and the screw loosening are tested at the same time, but it is also possible to test the life due to only the screw tightening operation. In this case, the motor 6 is not reversely rotated, but may be forwardly rotated instead of the reverse rotation. That is, by intermittently performing only forward rotation of the motor 6, only the screw tightening conditions can be repeated. Further, when testing the life due to only the screw loosening operation, the motor 6 may be rotated in the reverse direction instead of the normal direction without performing the normal rotation. In other words, by intermittently performing only reverse rotation of the motor 6, only the screw loosening condition can be repeated.

  In the example shown in FIG. 4, the cylinder 22 is driven to raise and lower the inertia 28 (shaft 30) while the next torque is generated after the torque is generated, but one torque is generated. After the end, the shaft 30 may be raised, the next torque may be generated in that state, and then the shaft 30 may be lowered to generate the torque again. There is no significant change in the thrust load applied to the rotary drive mechanism 4 between the position where the bit is raised and the position where the bit is lowered, so that the torque may be generated at any position where the rotating shaft 30 is raised. For the purpose of a life test, it is sufficient to move the rotary shaft 30 back and forth.

  In the above-described embodiment, the rotation driving mechanism 4 of the screw tightening driver 2 has been described as an example. However, the present invention is not limited to the screw tightening driver 2, and the present invention is not limited to the rotation driving mechanism of other tools such as a torque wrench. It can be applied to a life test of a simple rotational drive mechanism.

  The present invention is applicable to a life test apparatus and method for a rotary drive mechanism such as a screw tightening driver.

Claims (13)

A life test device for a rotary drive mechanism,
A shaft configured to be connectable to the rotational drive mechanism;
A life test apparatus for a rotary drive mechanism, comprising: a weight fixed to the shaft and configured to be rotatable about the shaft. A life test apparatus for a rotary drive mechanism according to claim 1,
A life test apparatus for a rotary drive mechanism, wherein the weight is configured to be rotatable in both directions. A life test apparatus for a rotary drive mechanism according to claim 1,
A life test apparatus for a rotary drive mechanism, wherein the weight is configured to be movable in the longitudinal direction of the shaft. A life test apparatus for a rotary drive mechanism according to claim 3,
A support member for rotatably supporting the weight;
A slide guide for guiding the support member so as to be movable in the longitudinal direction of the shaft;
And a drive source for reciprocally moving the support member in the longitudinal direction of the shaft. A life test apparatus for a rotary drive mechanism according to claim 1,
A life test apparatus for a rotary drive mechanism, wherein the weight is configured to be removable. A life test apparatus for a rotary drive mechanism according to claim 1,
The drive source of the rotational drive mechanism is an electric motor,
A life test apparatus for a rotary drive mechanism, further comprising a display device that detects a current flowing through the electric motor connected to the electric motor, converts the current into a torque value, and displays the converted torque value. A life test apparatus for a rotary drive mechanism according to claim 1,
The rotation drive mechanism is a rotation drive mechanism incorporated in a screw tightening driver,
The shaft has the same shape as that of a bit used in the screw tightening driver. A life test apparatus for a rotary drive mechanism according to claim 1,
A frame,
A reciprocating drive attached to the bottom of the frame;
A support member attached to the drive shaft of the reciprocating drive unit;
A weight rotatably supported by the support member;
A shaft provided on the rotating shaft of the weight, and
The frame has an attachment portion for attaching a device having the rotation drive mechanism, and the shaft is connected to the rotation drive mechanism when the device is attached to the frame. A life test device for a rotary drive mechanism characterized by A life test method for a rotary drive mechanism,
A weight of a predetermined weight is connected to the rotary drive mechanism;
A life test method for a rotary drive mechanism, wherein the torque is repeatedly applied to the rotary drive mechanism by driving the rotary drive mechanism and repeatedly rotating the weight. It is the life test method of the rotational drive mechanism of Claim 9, Comprising:
The rotational drive mechanism life test method is characterized in that the rotational drive mechanism is driven by repeating forward rotation and reverse rotation alternately. It is the life test method of the rotational drive mechanism of Claim 9, Comprising:
A life test method for a rotational drive mechanism, wherein the rotational drive mechanism is driven while the weight is reciprocated along a rotational axis. It is the life test method of the rotational drive mechanism of Claim 9, Comprising:
A life test method for a rotary drive mechanism, wherein the weight of the weight is adjusted based on the magnitude of torque to be applied to the rotary drive mechanism. It is the life test method of the rotational drive mechanism of Claim 9, Comprising:
A method for testing the life of a rotary drive mechanism, comprising: obtaining a torque value applied to the rotary drive mechanism from a current value flowing in a motor driving the rotary drive mechanism and displaying the torque value on a display device.

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