JPH0581674U - Ball screw torque automatic measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To enable easy and accurate ball screw torque measurement work. [Structure] The guide bar 5 is bridged between the columns 3 and 4 which are erected on the base 2. The base 2 is provided with the headstock 6 and the tailstock 7, and the shaft 17 of the miniature ball screw 16 is supported in parallel with the guide bar 5 therebetween. A slide bar 20 is slidably provided on the guide bar 5, and a nut holder 21 provided at a lower end portion of the slide bar 20 fixes a nut 18 of a miniature ball screw 16. Slide bar 2
A pair of resistance wire strain gauges 22 forming a 4-gauge bridge circuit are bonded to both surface sides of a leaf spring 21 that connects the middle portions of 0s. Shaft 17 by reversible motor 11
Is rotated to bend the leaf spring 21, and the output change of the bridge circuit is amplified by the dynamic strain gauge 25 and converted into a voltage change. This voltage change is displayed on the recorder 26 and recorded.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ball screw torque automatic measuring device for automatically measuring the torque of a ball screw.

[0002]

[Prior Art]

 Conventionally, when performing a product inspection of a miniature ball screw used as a feed screw of a machine tool, for example, a manual torque meter 41 shown in FIG. 4 is used to measure the torque. That is, the manual torque meter 41 has a torque meter main body 42 and a thimble 43, and both outer peripheral surfaces 42a and 43a are provided with graduations facing each other. The thimble 43 is rotatably supported by the torque meter main body 42 so as to receive a predetermined torque according to the amount of rotation when it is rotated in one direction or the other direction, and a chuck 44 is provided on the end side thereof. It is provided.

When performing torque measurement using the manual torque meter 41, first, the chuck 46 is used to fix and support the shaft 46 of the miniature ball screw 45 to the thimble 43, and then, as shown in FIG. As described above, the nut 47 of the miniature ball screw 45 is rotated in both directions with the torque meter main body 42 fixed. Then, the torque is read from the positional deviation between both the scales a and b at this time, and the quality of the miniature ball screw 45 is inspected from the minimum value and the maximum value.

[0004]

[Problems to be solved by the device]

 However, in the measurement work using such a conventional manual torque meter 41, it is difficult to instantly read both scales that are constantly moving when the nut 47 is rotated to both sides. However, there is a problem in that the measurement results cannot be performed unless the operator is skilled, and the measurement results vary from person to person.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an automatic ball-screw torque measuring device capable of performing a ball-screw torque measuring operation easily and accurately.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, in the present invention, a guide bar bridged between two points spaced apart from each other in a main body of a device and a support for rotatably supporting a shaft of a ball screw in parallel with the guide bar. Means, a motor that rotates the shaft, and a slide bar that is slidably supported by the guide bar and that fixes a nut of a ball screw that is screwed to the shaft via a plate-shaped flexible member. , One pair is bonded to each of the one surface and the other surface of the flexible member along the direction orthogonal to the guide bar, and the contact points of both sides connected in series are input. Side strain gauges constituting the Wheatstone bridge circuit and a dynamic strain gauge connected to the output side of the Wheatstone bridge circuit constituted by the four strain gauges, amplifying the bridge output and converting it into voltage. , And a display means for displaying the output change of the animal strain gauge.

[0007]

[Action]

 In the above configuration, when the shaft of the ball screw rotatably supported by the supporting means is rotated in one direction by the motor during the measurement work, the nut is prevented from rotating by the slide bar, while the nut is blocked by the slide bar. Is moved along the guide bar. At this time, the torque applied to the nut is applied to the flexible member as a bending moment, so that the surface of one surface and the other surface of the flexible member along the direction perpendicular to the guide bar is distorted. Along with this, the four strain gauges, which are adhered in pairs to both surfaces of the flexible member, are also distorted, and the respective resistance values change.

Here, the four strain gauges form a Wheatstone bridge circuit with the contacts connected in series on both sides of the flexible member as input sides, so that the output of the Wheatstone bridge circuit is The output on the side changes, the change in the bridge output is amplified by the dynamic strain gauge and converted into a change in voltage, and is displayed as a measured value by the display means.

Moreover, since the strain on the surface of the flexible member is detected by the four strain gauges forming the Wheatstone bridge circuit, the plate-shaped flexible member is twisted during the measurement work. Even in this case, the bridge output due to the twist can be canceled by the strain gauge paired on one side and the strain gauge paired on the other side.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. That is, as shown in FIG. 1, the ball screw torque automatic measuring device 1 of the present invention has a base 2 which is the main body of the device. Posts 3 and 4 are erected on the base 2 so as to be spaced apart from each other, and guide bars 5 are bridged to the tip ends of the posts 3 and 4. Further, the base 2 is provided with a headstock 6 located on the side of one of the columns 3 which is a supporting means, and a tailstock 7 located on the side of the other column 4, and the tailstock 7 is It is supported by the base 2 via a carriage 8 and is movable in the extending direction of the guide bar 5. The headstock 6 and the tailstock 7 each have a center 9, 9, and the center 9 of the headstock 6 is rotatably supported by the headstock 6 via a bearing 10. A reversible motor 11 is connected to a rotary shaft 13 of a gear head 12. Further, the lever-sible motor 11 is connected to a control box 14, and the control box 14 is connected to limit switches 15 and 15 arranged at both ends of the guide bar 5, respectively.

On the other hand, a miniature ball screw 16 is supported between the headstock 6 and the tailstock 7. The miniature ball screw 16 has a shaft 17 and a nut 18 screwed to the shaft 17 via a ball (not shown). Both ends of the shaft 17 are supported by the centers 9, 9 of both the headstock 6 and the tailstock 7 so as to be parallel to the guide bar 5, and the shaft 17 of the headstock 6 is connected via a connecting member 19. It is connected to the center 9. On the other hand, one end of the slide bar 20 is supported by the guide bar 5 via a ball bearing (not shown) so as to be movable in the axial direction. The slide bar 20 hangs vertically downward from the guide bar 5, and the middle part thereof is connected by a plate spring 21 which is a plate-like flexible member, and the pond end nut holder is provided. There is. The nut holder is externally fitted and fixed to the nut 18, whereby the rotation of the nut 18 is restricted and the nut 18 is supported by the slide bar 20.

Resistance wire strains 22a and 22b are bonded in pairs to one surface 21a of the leaf spring 21 along the direction perpendicular to the guide bar 5, and the other surface is also similarly bonded. A pair of resistance wire strain gauges (not shown) are bonded to each other, and these resistance wire strain gauges 22 are connected to the input side of the bridge box 24 via lead wires 23. The resistance wire strain gauges 22 are connected to each other inside the bridge box 24 so as to form a Wheatstone bridge circuit as shown in FIG. Resistance wire strain gauges that make a pair on the surface are connected in series with each other, and the contact points on both surfaces are used as the input side of the Wheatstone bridge circuit. That is, in FIG. 2, R ₁ and R ₂ are resistance line strain gauges 22a and 22b that form a pair on one surface 21a, and R ₃ and R ₄ are resistance line strain gauges that form a pair on the other surface. The contact a of R ₁ and R _{2 and} the contact b of R ₃ and R ₄ serve as the input side of the Wheatstone bridge circuit, and the contact c of R ₁ and R _{3 and} the contact of R ₂ and R ₄ The contact d of is the output side.

Further, a dynamic strain gauge 25 for amplifying the bridge output of the Wheatstone bridge circuit and converting it into a voltage is connected to the bridge box 24, and the dynamic strain gauge 25 has a voltage change output from the dynamic strain gauge 25. A recorder 26, which is a display unit for displaying, is connected.

In the present embodiment having the above-described configuration, when the shaft 17 of the miniature ball screw 16 is rotated in one direction by the reversible motor 11 via the connecting member 19 during the measurement work, the nut 18 slides. While its rotation is blocked by 20, the nut 18 moves the slide bar 20 along the guide bar 5 in one direction (arrow direction). When the slide bar 20 is eventually moved to the one end side of the guide bar 5, one limit switch 15 detects this, and in response thereto, the reversible motor 11 is rotated in the reverse direction. When the shaft 17 is rotated in the other direction accordingly, the slide bar 20 is moved in the other direction (direction indicated by the arrow) along the guide bar 5, and then the other limit switch 15 detects this and In response to this, the rotation of the reversible motor 11 is stopped. That is, the slide bar 20 is reciprocated along the guide bar 5.

On the other hand, in such a case, the torque applied to the nut 18 with the rotation of the shaft 17 is applied to the plate spring 21 as a bending moment, so that one of the leaf springs 21 along the direction perpendicular to the guide bar 5 is Of the surface 21a of the leaf spring 21 and the surface of the other surface of the leaf spring 21. As a result, the four resistance wire strain gauges 22 bonded to each of the surfaces of the leaf spring 21 are distorted, and (R ₁ , R ₂ , R ₃ , R ₄ ) changes. Therefore, the output on the output side of the Wheatstone bridge circuit (Fig. 2) formed by the four resistance wire strain gauges 22 changes, and the change in the bridge output is amplified by the dynamic strain gauge 25 and changes in the voltage. As it is converted, it is displayed and recorded by the recorder 26 as a measurement value.

That is, FIG. 3 is a graph showing an example of the measurement results recorded by the recorder 26 of this embodiment, in which the vertical axis represents voltage and the horizontal axis represents time. Therefore, if the relationship between the torque and the voltage when the predetermined torque is applied to the nut 18 is obtained in advance, the change in the torque applied to the nut 18 when the shaft 17 rotates can be known from the change in the voltage. It is possible to measure the minimum value and the maximum value of the torque applied to the miniature nut from the range of the maximum value and the minimum value of the voltage change. In the graph shown in FIG. 3, one scale on the vertical axis indicating the voltage indicates a torque of 20 gf / cm.

Moreover, since the strains on the one surface 21a and the other surface of the leaf spring 21 are detected by the four resistance wire strain gauges 22 forming the Wheatstone bridge circuit, the above-mentioned measurement work is performed. Even when the leaf spring 21 is twisted, the bridge output caused by the twist is generated by the resistance wire strain gauge 22 that makes a pair on one surface and the resistance wire strain gauge that makes a pair on the other surface. 22 and can be offset. Therefore, the torque of the miniature ball screw 16 can be accurately measured.

In addition, in the present embodiment, since the leaf spring 21 has a structure that vertically hangs downward from the guide bar 5, the leaf spring 21 does not distort due to its own weight, and at the time of measurement work, It is not necessary to consider the distortion due to the weight of the leaf spring 21. Therefore, after the above-mentioned fluctuation of the bridge output is amplified by the dynamic strain gauge 25 and converted into a voltage change, it can be directly used as the measurement result without correction. As a result, the dynamic strain gauge The circuit configuration of can be simplified.

[0019]

[Effect of the device]

 As described above, according to the present invention, the rotation of the nut due to the rotation of the shaft of the ball screw is prevented by the slide bar that fixes the nut through the plate-shaped flexible member. The applied bending moment is converted into a bridge output of a Wheatstone bridge circuit composed of four strain gauges provided on the flexible member, and then the change is converted into a change in voltage by a dynamic strain gauge, and a display means. It was made to display by. Therefore, if the relationship between the torque and the voltage when a predetermined torque is applied to the nut is obtained in advance, whether the change in the torque applied to the nut when the shaft rotates changes the voltage displayed by the display means. It is possible to measure the torque applied to the nut.

Moreover, since the strain on the surface of the flexible member is detected by the four strain gauges that form the Wheatstone bridge circuit, the plate-shaped flexible member is twisted during the measurement work. Even in this case, the bridge output due to the twist can be canceled by the strain gauge paired on one side and the strain gauge paired on the other side. Therefore, it becomes possible to easily and accurately perform the ball screw torque measurement work.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a wiring structure in a bridge box of the embodiment.

FIG. 3 is a graph showing an example of measurement results of the same example.

FIG. 4 is an external perspective view of a manual torque measuring instrument showing a conventional example.

5 is an explanatory diagram showing a measuring operation using the manual torque measuring device of FIG. 4. FIG.

[Explanation of symbols]

 1 Ball Screw Torque Automatic Measuring Device 3, 3 Struts 5 Guide Bar 6 Headstock (Supporting Means) 7 Tailstock (Supporting Means) 11 Reversible Motor (Motor) 16 Miniature Ball Screws 17 Axis 18 Nuts 20 Slide Bars 21 Leaf Springs (Flexible member) 21a One surface 22 Resistance wire strain gauge (strain gauge) 25 Dynamic strain gauge 26 Recorder (display means)

Claims (1)

[Scope of utility model registration request] 1. A guide bar bridged between two points spaced apart from each other in an apparatus main body, a support means for rotatably supporting a shaft of a ball screw in parallel with the slide bar, and for rotating the shaft. Of the motor and a nut of a ball screw screwed to the shaft are fixed via a plate-shaped flexible member, and a slide bar slidably supported by the guide bar, and a straight line to the guide bar. A Wheatstone bridge circuit is configured with a pair of one side surface and the other side surface of the flexible member along the direction bonded one by one, and the contacts connected in series on both surface sides as input sides. The four strain gauges, a dynamic strain gauge connected to the output side of the Wheatstone bridge circuit configured by the four strain gauges, amplifying the bridge output and converting it into a voltage, and a change in the output of the dynamic strain gauge are displayed. An automatic ball-screw torque measuring device, comprising: