JP2005144646A - Tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool holder which contributes to the miniaturization of a spindle, and realizes cutting conditions optimum for a small-diameter tool. <P>SOLUTION: The tool holder is provided for mounting a cutting tool on a machine tool for machining a workpiece by rotating the cutting tool 11, and formed of a housing 1 which is irrotationally and detachably mounted in a spindle housing having a rotary spindle of the machine tool built therein; a planetary speed-increasing mechanism which is arranged in the housing, and has an input shaft 4 connected to the rotary spindle, a planetary roller 6 making contact with the input shaft, and an output shaft 21 making contact with the planetary roller; and a tool chuck 15 for fixing the cutting tool to the tip of the output shaft. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tool holder having a built-in mechanism for increasing the spindle speed of a machine tool that performs a cutting process using a rotary tool such as an end mill, and in particular, a tool rotation optimum for fine milling with a small-diameter tool. The present invention relates to a tool holder having a built-in tool rotation speed increasing mechanism using a friction drive for obtaining a number.

  Conventionally, when using a rotary tool of φ0.5mm or less, a method of increasing the spindle speed has been proposed to obtain optimum cutting conditions. The machine which mounts the speed increasing device is devised.

  For example, a speed increasing spindle disclosed in Japanese Patent Application Laid-Open No. 8-57734 includes a planetary roller speed increasing mechanism in which a central axis is eccentrically attached and brought into contact with an elastic member on the outer periphery of the planetary roller.

  Japanese Patent Laid-Open No. 8-150532 proposes a method in which a speed increasing gear for switching between low speed and high speed is mounted on the main shaft.

  Japanese Patent Laid-Open No. 6-198538 proposes a tool holder incorporating a planetary roller type speed increasing mechanism.

  FIG. 7 is a view showing a state in which a tool holder incorporating the conventional planetary roller type speed increasing mechanism is attached to the main spindle of a machine tool, and FIG. 8 is a partially broken longitudinal sectional view of the tool holder.

  In FIG. 7, a tool holder 90 is attached to the tip of the main spindle 61 of the machine tool. A processing tool 66 is fixed to the lower end of the tool holder 90. A fitting hole 61 a having a taper is formed at the tip portion of the main shaft 61, and the upper taper portion 63 of the tool holder 90 is fitted into the fitting hole 61 a and formed at the tip of the upper taper portion 63. The tool holder 90 is fixed to the spindle 61 by pulling the pull stud 65 inward of the spindle by a draw bar 64 disposed in the spindle 61.

  On the other hand, as shown in FIG. 8, in the housing 85 constituting the lower half of the tool holder 90, an input shaft 81 integrally provided at the lower end of the upper taper portion 63, the planetary roller 84, and the lower end portion A planetary roller type speed increasing mechanism including an output shaft 82 to which a processing tool 66 is attached is disposed. Here, when the housing 85 constituting the lower half of the tool holder 90 rotates together with the upper taper portion 63, the built-in speed increasing mechanism does not function, so the rotation preventing pin 67 is attached to the housing 85, and the housing 85 Is prevented from rotating with respect to the housing 68 of the main shaft.

In the conventional tool holder configured as described above, the upper tapered portion 63 of the tool holder 90 rotates together with the main shaft 61, so that the machining tool 66 is rotationally driven at an increased speed.
JP-A-8-57734 JP-A-8-150532 JP-A-6-198538

However, the above conventional tool holder has the following problems.
(1) A mechanism for fixing the upper tapered portion 63 of the tool holder 90 is required inside the main shaft 61, the main shaft diameter increases, and the inertia moment of the main shaft increases.
(2) As the main shaft diameter increases, it becomes necessary to increase the bearing rigidity, so that the bearing becomes larger, the peripheral speed of the bearing increases, and problems such as heat generation and vibration occur.
(3) When the tool holder is replaced, a rotation balance error for each tool holder occurs.
(4) When exchanging the tool holder by the automatic tool changer, the tool rotation shaft is shaken due to repeated attachment errors.

  For these reasons, in the conventional machining center and NC milling machine, the maximum spindle rotational speed is in the range of 8,000 to 20,000 rpm.

  Therefore, for example, when two types of tools with extremely different cutting conditions are attached to the same machine tool, for example, rough finishing is performed with a φ8 mm processing tool and finishing is performed with a φ0.4 mm processing tool. It was difficult to process with a small diameter tool that required high-speed rotation.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the size of the main shaft and to realize optimum cutting conditions for a small-diameter tool.

  In order to solve the above-mentioned problems and achieve the object, a tool holder according to the present invention is a tool holder for attaching the cutting tool to a machine tool for cutting a workpiece by rotating the cutting tool. And a housing that is non-rotatably and detachably mounted to a spindle housing that houses the rotating spindle of the machine tool, an input shaft that is disposed in the housing and is connected to the rotating spindle, and a contact with the input shaft A planetary speed increasing mechanism including a planetary roller that rotates, an output shaft that contacts the planetary roller, and a fixing unit that fixes the cutting tool to the tip of the output shaft.

  In the tool holder according to the present invention, the output shaft is disposed between an output roller that contacts the planetary roller, a tool attachment shaft to which the cutting tool is attached, and the output roller and the tool attachment shaft. And an Oldham type joint.

  Further, in the tool holder according to the present invention, the planetary speed increasing mechanism rotates on the circumference around the input shaft at the end of the input shaft and the input shaft rotatably supported by the housing. A plurality of planetary rollers that are freely attached, an outer ring that is detachably attached to the housing and contacts the outside of the plurality of planetary rollers, and the output shaft that is disposed at the center of the plurality of planetary rollers. It is characterized by that.

  In the tool holder according to the present invention, an inner diameter dimension of the outer ring is set to a dimension in which the planetary roller and the output shaft are lightly press-fitted.

  The tool holder according to the present invention further includes a thrust guide for suppressing the movement of the output shaft in the thrust direction.

  In the tool holder according to the present invention, the thrust guide includes a ball and a coil spring that biases the ball.

  In the tool holder according to the present invention, the planetary roller is a ball bearing having a small diameter.

  According to the present invention, the main shaft can be reduced in size, and a high-speed rotation motor and a speed increasing device can be combined, and high-speed rotation necessary for optimum cutting conditions for a small-diameter tool can be obtained.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a tool holder according to an embodiment of the present invention. FIG. 2 is a view showing the relationship among the output shaft, the planetary roller, and the outer ring. FIG. 3 is an exploded view showing attachment of the input shaft and the planetary roller. FIG. 4 is an exploded view showing attachment of the output shaft, the output roller, and the slider. FIG. 5 is a partially enlarged view showing attachment of the output roller and the thrust guide. FIG. 6 is a cross-sectional view showing attachment of a tool holder incorporating a tool speed increasing device to a machine tool.

  In FIG. 1, an input shaft 4 and an output shaft 5 are rotatably supported by bearings 7a and 7b, respectively, in a housing 1 constituting an outer shell of a tool holder. The input shaft 4 is fixed to the inner ring of the bearing 7a by the input shaft side lock nut 2. Further, it is fixed to the housing 1 by an input shaft lock nut 9. The output shaft 5 is fixed to the housing 1 by an output shaft lock nut 3. The rotary tool 11 is detachably attached to a tool chuck 15 at the tip of the output shaft 5. A hexagonal hole 4a for inserting a hexagonal shaft 72a formed at the tip of the main shaft 72 (see FIG. 6) of the machine tool main body 120 is formed at the upper end of the input shaft 4. The rotation of the main shaft 72 is transmitted to the input shaft 4 by fitting the hexagonal shaft 72 a of the main shaft 72 and the hexagonal hole 4 a of the input shaft 4.

  The planetary speed increasing mechanism is constituted by an outer ring 12 attached to the housing 1, a planetary roller 6, and an output roller 21 as shown in FIG. As the planetary roller 6, a commercially available small-diameter ball bearing is used in a single row or a double row. Further, the contact pressure necessary for power transmission by rolling friction is set by setting the inner diameter dl of the outer ring 12 to a dimension that allows light press-fitting to the outer diameter dc of the output roller 21 and the outer diameter ds of the planetary roller 6. Can be obtained.

  The outer ring 12 is detachably attached to the housing 1 as a spacer for holding the output shaft 5 in a fixed position.

  As shown in FIG. 3, the planetary roller 6 is rotatably attached to the input shaft 4 by a carrier guide 10, a planetary roller shaft 31, and a planetary roller spacer 32. The planetary roller shaft 31 also serves as a positioning pin for the input shaft 4 and the carrier guide 10. The carrier guide 10 is fixed to the input shaft 4 with a carrier guide fixing screw 33.

  In FIG. 4, the slider 41 disposed between the output roller 21 and the output shaft 5 constitutes an Oldham joint between the output roller 21 and the output shaft 5. Therefore, the eccentricity of 0.01 to 0.02 mm that occurs when the input shaft 4 and the output shaft 5 are assembled into the housing 1 can be removed.

  The output roller 21 is detachably attached to the output shaft 5 in the thrust direction via a slider 41. In order to prevent the output roller 21 from swinging in the thrust direction during high-speed rotation, a ball plunger composed of a steel ball 51 and a spring 52 is provided at the center of the lower end surface of the input shaft 4 as a thrust guide, as shown in FIG. It has been.

  Next, FIG. 6 shows a method for attaching a tool holder incorporating the tool speed increasing device of the present embodiment to a machine tool.

  The spindle motor 71 is fixed to the machine tool main body 120. The housing 1 of the tool holder has a tapered portion 1a at the top, is positioned using the tapered hole 100a in the spindle housing 100 of the machine tool main body 120, and the spindle housing 100 of the machine tool main body 120 by the clamp units 73a and 73b. It is fixed to be removable and non-rotatable. A rotating shaft 72 of the motor 71 is connected to the input shaft 4 through a joint that can be inserted and removed. The joint is, for example, the fitting of the hexagonal shaft 72a of the main shaft 72 and the hexagonal hole 4a of the input shaft 4 described above, but is not limited thereto, and the cross-shaped hole and the cross-shaped shaft are not limited thereto. Other types of joints, such as a combination of The rotation of the motor 71 is increased by the tool rotation speed increasing device and transmitted to the output shaft 5.

  Therefore, the rotary tool 11 rotates at a speed increased with respect to the rotational speed of the motor 71.

  As described above, in the present embodiment, the housing of the tool holder is fixed to the main body of the machine tool so as not to rotate, and the rotating portion and the speed increasing mechanism are disposed inside the housing of the tool holder. It is not necessary for the rotating main shaft to have a diameter large enough to insert the upper tapered portion of the tool holder, and the main shaft can be reduced in diameter.

  Along with this, the bearing that supports the main shaft does not require much rigidity, so that the bearing can be downsized.

  In addition, the planetary speed increasing mechanism can be downsized, and the motor can be downsized.

It is sectional drawing of the tool holder which incorporated the tool speed increasing apparatus concerning one Embodiment of this invention. It is explanatory drawing of the friction drive device concerning one Embodiment of this invention. It is explanatory drawing of the attachment method of the planetary roller concerning one Embodiment of this invention. It is explanatory drawing of the attachment method of the output roller and slider concerning one Embodiment of this invention. It is explanatory drawing which shows the relationship between the output roller and thrust guide concerning one Embodiment of this invention. It is sectional drawing explaining the connection of the tool holder and spindle motor concerning one Embodiment of this invention. It is explanatory drawing of a prior art. It is sectional drawing which shows the structure of the speed increasing apparatus built-in tool holder of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Input side bearing lock nut 3 Output shaft side lock nut 4 Input shaft 5 Output shaft 6 Planetary roller 7a, 7b Bearing 8a, 8b Spacer 9 Input shaft lock nut 10 Carrier guide 11 Rotating tool 12 Outer ring 13 Locking nut 15 Tool chuck 21 Output roller 31 Planetary roller shaft 32 Planetary roller spacer 33 Carrier guide fixing screw 41 Slider 51 Steel ball 52 Spring 61 Main shaft 62 Motor 63 Upper taper portion 64 Draw bar 65 Pull stud 66 Rotary tool 67 Anti-rotation pin 71 Motor 72 Rotary shaft 73a, 73b Clamp unit 81 Input shaft 82 Output roller 84 Planetary roller 85 Housing 90 Tool holder

Claims (7)

A tool holder for attaching the cutting tool to a machine tool for cutting a workpiece by rotating the cutting tool,
A housing that is non-rotatably and detachably mounted to a spindle housing that houses a rotating spindle of the machine tool;
A planetary speed increasing mechanism including an input shaft disposed in the housing and coupled to the rotation main shaft, a planetary roller in contact with the input shaft, and an output shaft in contact with the planetary roller;
Fixing means for fixing the cutting tool to the tip of the output shaft;
A tool holder comprising:   The output shaft includes an output roller that comes into contact with the planetary roller, a tool mounting shaft to which the cutting tool is mounted, and an Oldham coupling that is disposed between the output roller and the tool mounting shaft. The tool holder according to claim 1.   The planetary acceleration mechanism includes the input shaft rotatably supported by the housing, and a plurality of planetary rollers rotatably mounted on a circumference around the input shaft at an end of the input shaft. 2. An outer ring that is detachably attached to the housing and is in contact with an outer side of the plurality of planetary rollers, and the output shaft that is disposed at a central portion of the plurality of planetary rollers. Tool holder.   4. The tool holder according to claim 3, wherein an inner diameter of the outer ring is set to a dimension in which the planetary roller and the output shaft are lightly press-fitted.   The tool holder according to claim 1, further comprising a thrust guide for suppressing movement of the output shaft in a thrust direction.   The tool holder according to claim 5, wherein the thrust guide includes a ball and a coil spring that biases the ball.   The tool holder according to claim 1, wherein the planetary roller is a small-diameter ball bearing.

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