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JP-2026075743-A - machine tools

JP2026075743AJP 2026075743 AJP2026075743 AJP 2026075743AJP-2026075743-A

Abstract

[Problem] To provide a machine tool that can determine the gripping force of the gripping part with high precision using an inexpensive configuration. [Solution] The system comprises a first spindle 4 having a collet chuck 41 for gripping a workpiece W1, a first headstock 3 that rotatably supports the first spindle 4, an air cylinder 33 that generates a driving force to change the state of the collet chuck 41 between a gripping state for gripping the workpiece W1 and a release state for releasing the workpiece W1, a non-rotating transmission member 34 that transmits the driving force received from the air cylinder 33, a rotating transmission member 45 that rotates together with the first spindle 4 and transmits the driving force received from the non-rotating transmission member 34 to the collet chuck 41, a strain detection means 46 attached to the non-rotating transmission member 34 that detects the strain of the non-rotating transmission member 34 that occurs when the driving force is transmitted from the air cylinder 33 to the collet chuck 41, and a derivation unit 23 that derives the gripping force of the collet chuck 41 based on the detection result of the strain detection means 46. [Selection Diagram] Figure 5

Inventors

  • 香川 祐樹
  • 志鎌 耕一郎
  • 出野 真敏
  • 齋藤 弘樹
  • 梶 優介

Assignees

  • スター精密株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (6)

  1. A spindle having a gripping part for gripping a workpiece, A headstock that rotatably supports the main spindle, An actuator mounted on the spindle head generates a driving force to change the state of the gripping portion between a gripping state in which the workpiece is gripped and a release state in which the workpiece is released. A non-rotational transmission member attached to the headstock and transmitting the driving force received from the actuator, A rotational transmission member that rotates together with the main shaft and transmits the driving force received from the non-rotating transmission member to the gripping portion, A strain detection means is attached to the non-rotating transmission member to detect the strain of the non-rotating transmission member that occurs when driving force is transmitted from the actuator to the gripping portion, A machine tool characterized by comprising a derivation unit that derives the gripping force of the gripping unit based on the detection result of the strain detection means.
  2. The rotation transmission member includes a claw member capable of changing its position between a first position in which the gripping portion is in the gripping state and a second position in which the gripping portion is in the release state, and a shifter capable of changing the position of the claw member between a first position in which the claw member is in the first position and a second position in which the claw member is in the second position by moving in the axial direction of the main shaft. The non-rotating transmission member has a shifter lever that moves the shifter in the axial direction, The machine tool according to claim 1, characterized in that the strain detection means detects the strain of the shifter lever.
  3. The machine tool according to claim 2, characterized in that the strain detection means detects strain in the area between the force-receiving portion where the shifter lever receives driving force from the actuator and the action portion where the reaction force received by the shifter lever from the shifter acts when the driving force received by the shifter is transmitted to the shifter.
  4. The shifter lever is capable of pivoting around the pivot axis, and by pivoting, it moves the shifter in the direction of the axis. The machine tool according to claim 3, characterized in that the strain detection means detects the strain on the side surface of the shifter lever, which is formed parallel to the pivot axis.
  5. The shifter lever is capable of pivoting around the pivot axis, and by pivoting, it moves the shifter in the direction of the axis. The machine tool according to claim 3, characterized in that the strain detection means detects strain in a part where the distance from the pivoting center axis is shorter than the distance from the force-receiving part and the action part.
  6. The machine tool according to any one of claims 1 to 5, characterized in that the derivation unit derives the gripping force of the gripping unit based on the maximum value of the strain of the non-rotation transmission member during the state change from the release state to the gripping state detected by the strain detection means.

Description

This invention relates to a machine tool for machining a workpiece held in a spindle. A machine tool is known that processes a rod-shaped workpiece held by a rotatable spindle (see, for example, Patent Document 1). The spindle of this machine tool is rotatably supported on the headstock. The spindle is equipped with a gripping section that changes between a gripping state (holding the workpiece) and a release state (releasing the workpiece). The gripping section is operated by an actuator fixed to the headstock. In the machine tool described in Patent Document 1, the actuator drives a shifter lever, causing the shifter to oscillate and the jaw member to tilt. This tilting of the jaw member moves the push sleeve and chuck sleeve along the axis of the spindle, allowing the gripping section to grip or release the workpiece. Generally, the spindle is equipped with an adjustment nut as an adjustment means for adjusting the gripping force of the workpiece. This adjustment nut is mounted on the spindle body so as to be rotatable relative to the spindle body. By rotating it relative to the spindle body, the axial position of the adjustment nut changes, altering the gripping force of the workpiece. When machining a workpiece of a different diameter or material than the one previously processed, the machine tool operator performs a setup operation. This involves inserting the next workpiece into the gripping section and rotating the adjustment nut relative to the spindle body to adjust the gripping force. The operator then manually operates the shifter lever to displace the shifter, estimates the gripping force of the gripping section from the force required for this operation, and repeats the relative rotation and estimation process until the desired gripping force is achieved, at which point the adjustment nut is fixed to the spindle body. Japanese Patent Publication No. 2020-97075 This is a simplified plan view showing the internal configuration of the NC lathe according to this embodiment.This is a perspective cross-sectional view of a portion of the first headstock and first spindle shown in Figure 1.Figure 1 shows a cross-sectional view of the first headstock and first spindle, taken from above by cutting them through a horizontal plane passing through the axis of the first spindle.Figure 3 is an enlarged view of the first main shaft and rotational transmission member shown.Figure 1 is a perspective cross-sectional view showing a portion of the first headstock, cut away to reveal the non-rotating transmission member and a portion of the rotating transmission member.Figure 5 is a perspective cross-sectional view of a portion of the shifter lever, cut along the direction of extension of the shifter lever.Figure 5 shows the shifter lever as viewed from the rear end of the main shaft.Figure 1 is a control block diagram of the NC lathe.This graph shows an example of the distortion of the shifter lever detected by the distortion detection means when the first spindle shown in Figure 1 changes state from a released state to a gripped state.Figure 1 is a flowchart showing the automatic adjustment operation of the gripping force in the first spindle.(a) is a schematic diagram showing the positional relationship between the force acting on the shifter lever shown in Figure 5 and the pivot center, and (b) is a schematic diagram showing a modified shifter lever and the positional relationship between the force acting on the modified shifter lever and the pivot center. The embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention will be explained using an example of its application to a Swiss-type NC (Numerical Control) lathe. That is, the NC lathe described below corresponds to an example of a machine tool. Figure 1 is a simplified plan view showing the internal configuration of the NC lathe 1 according to this embodiment. As shown in Figure 1, the NC lathe 1 contains a control device 2, a first headstock 3, a first spindle 4, a guide bush 5, a first tool post 6, a second headstock 7, a second spindle 8, and a second tool post 9. The control device 2 is a computer that operates the first headstock 3, first spindle 4, first tool post 6, second headstock 7, second spindle 8, and second tool post 9 according to an NC program. In addition to operation using an NC program, the NC lathe 1 can also be operated by directly inputting commands to the control device 2 from the operation unit 11 (see Figure 8). The first headstock 3 moves in the Z1 axis direction along with the first spindle 4 in response to a signal from the control device 2. The Z1 axis direction is horizontal, and in Figure 1, it is the left-right direction. The first spindle 4 is rotatably supported on the first headstock 3. A first spindle motor 31 (see Figure 2) is also provided between the first headstock 3 and the first spindle 4. The first spindle motor 31 rotates in response to a s