JP2005319540A - Main spindle device of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a main spindle device which can confirm the mounted state of a tool on the main spindle, and further can be applied to a high speed main spindle. <P>SOLUTION: The main spindle comprises a clamping means for moving a draw bar 22 backward by a disc spring 30, and an unclamping means for moving the draw bar 22 forward by a cylinder-piston device. A probe 66 for detecting the position of the draw bar 22 is arranged so as to advance to and recede from the rear end portion 22a of the draw bar 22. The mounted state of the tool is confirmed by means of a plurality of sensors 70, 72, 74 for detecting the position of the probe 66. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spindle device for a machine tool in which a tool holder to which a tool is attached is engaged with an end surface of a spindle or / and an inner peripheral surface of a tapered hole to mount the tool holder on the spindle. In particular, the present invention relates to a spindle device of a machine tool applicable to a spindle for high-speed rotation.

  An example of a spindle device of a machine tool is disclosed in the specification and drawings of Japanese Patent No. 3159923 related to the applicant's application (see Patent Document 1). In this main shaft device, a draw bar is inserted coaxially into a hollow portion of a main shaft that is rotatably provided with respect to a housing. A collet that opens and closes as the draw bar moves in the axial direction is provided at the tip of the draw bar. The pull stud at the rear end of the tool holder to which the tool is attached is locked and released with a collet.

  When a tool is mounted on the main shaft, the draw bar is urged rearward with respect to the main shaft by the repulsive force of a plurality of disc springs, for example, a plurality of disc springs. The collet holds the stud. Also, when removing the tool from the main shaft, the unclamping means provided at the rear of the main shaft is actuated, and a force that overcomes the repulsive force of the disc spring is applied to the piston to push the draw bar forward relative to the main shaft. The collet opens the pull stud.

Japanese Patent No. 3159923

  In the machine tool with a tool change device described in Patent Document 1 described above, chips generated by machining and machining fluid scattered in the machining area are applied to the outer peripheral portion of the tool holder, particularly the mounting surface to the spindle such as the tapered portion of the tool holder. May adhere. When the tool in such a state is mounted on the spindle, the flange end surface or taper portion of the tool holder does not properly adhere to the end surface or taper hole of the tip end of the spindle, which is the reference surface when the tool is mounted. For this reason, there is a problem that accurate positioning of the tool is not performed, the accuracy of mounting the tool on the spindle is remarkably lowered, and the machining accuracy is also remarkably lowered. In addition, a sensor for detecting the position of the draw bar is provided at the rear part of the spindle unit, and the draw bar is equipped with a dog, so the length of the draw bar increases, the weight and inertia increase, and the rotational unbalance amount Increase. When such a spindle device is rotated at a high speed, there is a problem that vibrations are large and the machining accuracy is adversely affected.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to confirm whether or not a tool is mounted on the spindle and whether or not the tool is mounted at a correct position. It is possible to provide a spindle device of a machine tool that can be applied to a spindle that rotates at high speed.

  In order to achieve the above-described object, the present invention provides a machine tool for mounting a tool holder on a main shaft by engaging a tool holder to which a tool is attached to an end surface of a tip end portion of the main shaft and / or an inner peripheral surface of a tapered hole. In the main shaft device, a hollow housing, a hollow main shaft rotatably supported by the housing via a bearing, and a pull stud provided in a tool holder through the hollow portion of the main shaft coaxially with the main shaft A draw bar having a collet for locking and releasing, a clamping means for moving the draw bar backward by a repulsive force of an elastic biasing member provided between the main shaft and the draw bar, and locking the tool holder; An unclamping means that is mounted in the housing and moves the draw bar forward against the repulsive force of the elastic biasing member to open the tool holder, and toward the rear end of the draw bar Whether the tool holder is mounted on the main shaft is configured to include a probe that can move forward and backward, abuts against the rear end of the draw bar, detects the position of the draw bar, and a plurality of sensors that detect the stop position of the probe. There is also provided a spindle device for a machine tool comprising tool mounting state confirmation means for detecting whether or not the tool holder is mounted at a correct position.

  As described above, the spindle device of the present invention has the clamp means for moving the draw bar backward, the unclamp means for moving the draw bar forward, and the probe for detecting the position of the draw bar and the tool mounting state detection means. It is comprised. Since it is such a structure, the position of a draw bar can be detected with the probe provided in the non-rotating part. Further, since it is not necessary to attach a member for detecting the position to the draw bar that rotates together with the main shaft, the main shaft rotating portion can be made small, and the mounting state of the tool can be detected safely and accurately.

  A probe for detecting the position of the draw bar is provided in the non-rotating part, and the tool mounting state checking means for detecting whether the tool holder is mounted on the spindle or whether the tool holder is mounted at the correct position is not rotated. Since it is attached to the housing, the position of the draw bar can be detected safely and accurately. Further, since it is not necessary to provide a device for detecting the position of the draw bar, the draw bar can be shortened, and vibration and inertia can be reduced. Therefore, a spindle device suitable for a spindle of high speed rotation with small vibration can be obtained.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the entire spindle device of a machine tool according to the present invention. FIG. 2 is a flowchart showing the operation of checking the tool mounting state.

  A main spindle device 10 of a machine tool includes a hollow housing 12 and a hollow main spindle 14 that is rotatably supported by the housing 12 via bearings 16a, 16b, and 16c. In order to rotationally drive the main shaft 14, a rotor 32 of a built-in motor is fixed to the outer peripheral surface of the main shaft 14, and a stator 34 is fixed to the inner peripheral surface of the housing 12. A tapered surface 14a that expands in a conical shape in the distal direction of the main shaft 14 is formed as a reference surface at the distal end portion of the main shaft 14, and a truncated cone shape of the tool holder 18 in which the tool 20 is attached to the tapered surface 14a. The taper portion 18a is attached.

  A draw bar 22 is inserted into the hollow portion of the main shaft 14 so as to be movable in the axial direction. A guide tube 26 is inserted and fixed in a distal end region of the main shaft 14 in a hollow portion of the main shaft 14, and the draw bar 22 is inserted into the guide tube 26 and guided in the axial direction of the main shaft 14. A disc spring 30 as an elastic biasing member is disposed between the guide tube 26 and the main shaft 14 in a compressed state, and the disc bar 30 causes the draw bar 22 to move toward the rear end of the main shaft 14 along the central axis. Be energized. A collet 28 that can be engaged with a pull stud 18 b provided at the rear end of the tapered portion 18 a of the tool holder 18 is disposed at the distal end portion of the draw bar 22. The collet 28 engages and pulls in the pull stud 18 b when the draw bar 22 is retracted in the main shaft 14, and locks the tool holder 18 to the tip of the main shaft 14. When the draw bar 22 moves forward, the collet 22 expands and the engagement with the pull stud 18b is released, and the tool holder 18 can be removed from the tapered surface 14a at the tip of the main shaft 14. Instead of the disc spring 30, another elastic biasing member such as a coil spring can be used.

  The housing referred to in the claims includes a state in which a bracket 42 is attached to the housing 12. In order to move the draw bar 22 back and forth along the central axis, an unclamping device is provided in the rear end region of the main shaft 14 and the draw bar 22. The unclamping device is a cylinder 44 fixed in a hollow portion of a bracket 42 provided on the upper portion of the housing 12, and is slidably disposed in the cylinder 44 and can come into contact with the rear end portion 22 a of the draw bar 22. And a tip end portion 46a of a piston 46 provided on the front end. Two hydraulic chambers separated in the axial direction are formed in the cylinder 44 by the piston 46, and hydraulic pressure is applied to each hydraulic chamber of the cylinder 44 from the hydraulic source 50.

  By supplying hydraulic pressure to the hydraulic chamber on the front side of the cylinder 44, the piston 46 is retracted from the rear end of the draw bar 22, the draw bar 22 is retracted by the urging force of the disc spring 30, and the collet 28 is pulled by the tool holder 18. The stud 18b is locked. By supplying hydraulic pressure to the hydraulic chamber on the rear side of the cylinder 44, the piston 46 moves forward, the front end portion 46 a of the piston 46 comes into contact with the rear end portion 22 a of the draw bar 22, and the biasing force by the disc spring 30 is increased. Against this, the draw bar 22 is moved forward. As a result, the collet 28 expands, the pull stud 18b of the tool holder 18 is opened, and the tool holder 18 can be removed from the tapered surface 14a of the main shaft 14.

  A cylinder 60 and a piston 62 are provided at the rear portion of the bracket 42, and the piston 62 can be moved forward and backward by the air pressure from the air pressure source 64. A probe 66 that contacts the rear end portion 22 a of the draw bar 22 and detects the position of the draw bar 22 is attached to the front of the piston 62. A proximity switch 70 and limit switches 72 and 74 for detecting the position of the draw bar 22 are provided behind the bracket 42 as sensors for checking the tool mounting state, and are connected to the control device 54, respectively. A proximity switch dog 76 and a limit switch dog 78 are attached to a dog bar 68 attached to the piston 62.

  With reference to FIG. 2, the operation for checking the tool mounting state will be described. The confirmation of the tool mounting state is performed by confirming whether or not the tool holder is mounted on the spindle and confirming whether or not the tool holder is mounted at the correct position. Check the tool mounting status every time a spindle rotation command is issued, check for the presence of a tool, check for tool contact, the tool is mounted on the spindle, and it must be in close contact with the tool. The spindle is rotated after confirming the above.

  In FIG. 2, when a command to rotate the main spindle of step S1 is issued, the probe 66 comes into contact with the rear end portion 22a of the draw bar 22 by the advancement of the piston 62 in step S2 probe advance. In step S3, whether the tool is present or not is checked. If the tool is not present, the spindle does not rotate. If the tool is present, the next step S4 confirms whether the tool is in close contact. If the adhesion check is abnormal, an alarm is issued to notify the abnormality. When the contact confirmation is normal, the probe 66 moves away from the rear end portion 22a of the draw bar 22 as the piston 62 moves backward in the next step S5. Then, the main shaft is rotated by the main shaft rotation in step S6, and processing is performed in step S7.

  The operation of each sensor for checking the tool mounting state in the present embodiment is as follows. When there is no tool in the presence / absence check of the tool, the proximity switch 70 is ON, the limit switch 72 is OFF, and the limit switch 74 is OFF. When the tool is present and the tool contact is abnormal, the proximity switch 70 is OFF, the limit switch 72 is ON, and the limit switch 74 is OFF. When the tool is present and the tool contact is normal, the proximity switch 70 is ON, the limit switch 72 is ON, and the limit switch 74 is OFF. If the spindle can be rotated in step S6, the proximity switch 70 is OFF, the limit switch 72 is OFF, and the limit switch 74 is ON, that is, the probe 66 is raised.

  In the present embodiment, FIG. 1 illustrates the case where the rear end portion 22a of the draw bar 22 protrudes rearward from the rear end surface of the main shaft 14, but the rear end portion 22a of the draw bar 22 is located on the inner side from the rear end surface of the main shaft 14. You may be drawn in. In short, it is sufficient that the piston 46 and the probe 66 have a structure that abuts against the rear end portion 22a of the draw bar 22. The cylinder 44 and the cylinder 60 are independently provided on the bracket 42, but the cylinder 60 is fixed on the piston 46, and the cylinder 60 moves together with the piston 46 for every clamping and unclamping. Also good.

  Instead of the proximity sensor 70 and the limit switches 72 and 74, a single position reading sensor such as a linear encoder for detecting the position of the piston 62, that is, the probe 66 in the axial direction may be provided to provide the same detection function. Further, the structure may be such that the position of the probe 66 itself is directly detected without using the dog bar 68. Furthermore, even if the tool holder 18 is a so-called two-surface restraint type tool holder in which the tool holder 18 is in close contact with both the end surface of the main shaft 14 and the tapered surface 14a, there are the same operations and effects as in this embodiment.

It is sectional drawing which shows the whole spindle apparatus of the machine tool of this invention. It is a flowchart which shows operation | movement of a tool mounting state confirmation.

Explanation of symbols

12 Housing 14 Spindle 18 Tool holder 22 Draw bar 22a Draw bar rear end 28 Collet 30 Belleville spring 44 Cylinder 46 Piston 50 Hydraulic source 54 Controller 60 Cylinder 62 Piston 64 Pneumatic pressure source 66 Probe 70 Proximity switch 72 Limit switch 74 Limit switch 74

Claims (1)

In a spindle device of a machine tool in which a tool holder to which a tool is attached is engaged with an end surface of a tip end portion of the spindle or / and an inner peripheral surface of a tapered hole, and the tool holder is attached to the spindle.
A hollow housing;
A hollow main shaft rotatably supported by the housing via a bearing;
A drawbar having a collet that is inserted coaxially with the main shaft into the hollow portion of the main shaft to lock and release the tool holder;
Clamping means for moving the draw bar backward by the repulsive force of an elastic biasing member provided between the main shaft and the draw bar, and locking the tool holder;
Unclamping means attached to the housing and moving the draw bar forward against the repulsive force of the elastic biasing member to open the tool holder;
A probe that is provided so as to be able to move forward and backward from the non-rotating portion toward the rear end portion of the draw bar, abuts on the rear end portion of the draw bar, and detects the position of the draw bar;
A tool mounting state confirmation means configured to detect whether or not the tool holder is mounted on the spindle, and / or whether or not the tool holder is mounted at a correct position, the sensor comprising a sensor for detecting the stop position of the probe;
A spindle device of a machine tool characterized by comprising:

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