JP3072755B2 - Tool holder mounting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called two-face constraint type tool holder mounting apparatus for a machine tool.

[0002]

2. Description of the Related Art In the field of machine tools, automatic machine tools such as a machining center having an automatic tool changer are widely used. In such an automatic machine tool such as a machining center, a plurality of tools suitable for a predetermined cutting process are mounted on a tool holder and stored in a magazine of an automatic tool changer. When the automatic tool change operation starts, the magazine rotates and a desired tool is selected, and is replaced with a tool already mounted on the tip of the spindle. This tool change process is performed while the tool is mounted on the tool holder. The conventional tool holder has a taper shank of 7/24 taper, and a tapered hole complementary to the taper shank is provided at the tip of the main shaft. The machining center is configured to clamp the tool holder to the tip of the spindle by fitting the taper shank into the taper hole of the spindle and pulling the tool holder to the rear of the spindle with a draw bar.

In order to prevent the tool holder from falling off during the tool changing process, particularly when the tool holder is clamped on the spindle and when the tool holder is removed from the spindle, a mechanism for holding the tool holder at the tip of the spindle by a spring force is provided. There is a tool holder mounting device. For example, Japanese Unexamined Patent Publication No. Hei 5-337773 and Japanese Utility Model Laid-Open Publication No. Hei 6-36738 disclose a case in which a through hole is formed in a main shaft at right angles to an axis, and a locking member is held in the through hole and a tool is held by the locking member. There is disclosed a device for preventing a tool holder from falling off, comprising a resilient member biasing in a direction.

On the other hand, recently, a so-called two-face constrained type tool holder is used in place of a conventional 7/24 taper tool holder (hereinafter simply referred to as a conventional tool holder) due to an increase in cutting speed. Is being done. Whereas the conventional tool holder is supported on the spindle only by the tapered surface,
The surface-constrained tool holder is configured to be supported not only on the tapered surface but also on the spindle end surface. Various types of two-sided tool holders have been proposed.
HSK shank is specified in DIN 69893 standard recently set by the German Standards Association. DIN6989
No. 3 standard defines only the shape and dimensions of the HSK shank, and does not define the mounting mechanism for the main shaft. Therefore, various mounting mechanisms have been proposed (for example, Japanese Patent Application Laid-Open No. 2-503768). No.).

[0005]

The above-mentioned JP-A-5-33
In a device for preventing a tool holder from falling off as disclosed in Japanese Unexamined Patent Publication No. 773 or No. 6-36738, a through hole must be formed in the main shaft, and the rigidity of the main shaft decreases, which is not preferable. Also, HSK
In a tool holder of a shank or other hollow taper shank, the diameter of the collet is expanded at the time of clamping to expand the hollow taper shank in the radial direction. At the time of unclamping, since there is no diameter-expanding action by the collet, the hollow taper shank shrinks, a gap is formed between the hollow taper shank and the tapered hole of the main shaft, and the tool holder easily falls off. Therefore, in the case of the HSK shank and other tool holders having a hollow taper shank, it is necessary to hold the tool holder to prevent the tool holder from dropping during automatic tool change. No hollow taper shank tool holder mounting device with a prevention mechanism is provided. The tool holder mounting device disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2-503768 does not have a mechanism for preventing the tool holder from falling off. An object of the present invention is to provide a tool holder mounting device for a hollow taper shank provided with a temporary fixing mechanism for a tool holder. It is a further object of the present invention to provide a tool holder mounting device having a reasonable tool holder drop-off prevention mechanism that does not reduce the rigidity of the spindle by forming a through hole in the spindle.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is achieved by a tool holder mounting device provided with a drop-off preventing means for engaging with a tool holder while allowing movement for attaching and detaching the tool holder. That is, the present invention inserts a hollow tapered shank of a tool holder into a tapered hole of a main shaft to bring an outer surface of the hollow tapered shank into contact with an inner surface of the tapered hole, and a flange surface of the tool holder to the main shaft. A tool holder mounting device for mounting the tool holder on the spindle by abutting the end face of the tool holder, wherein a jaw formed in an inner surface of a hollow taper shank of the tool holder to be tapered in a circumferential direction, and a tapered hole of the spindle. A split collet which is provided inside, engages with, and disengages with, the jaws of the tool holder inserted into the tapered hole while being radially expanded and contracted, and an axial rear side of the main shaft which is inserted inside the main shaft. A collet driver that engages with the inside of the split collet by moving the collet driver and expands the diameter of the split collet. And a draw bar for moving the collet driver forward and backward in the axial direction of the main shaft, and two draw bars provided at least in opposition to a circumferential gap of the split collet, and a hollow taper shank of the tool holder is provided with a taper hole of the main shaft. And a holding lever having an engaging portion that swings and engages with the jaw of the tool holder when inserted into the tool holder, and is disposed between the insertion hole of the collet driver and the drawbar of the spindle and the holding lever. Drop-off preventing means provided with an elastic urging member that constantly elastically urges the locking portion outwardly toward the jaw of the tool holder in response to the swinging operation of the holding lever. The gist is a tool holder mounting device that performs

[0007]

When the hollow taper shank of the tool holder is inserted into the tapered hole of the main shaft, even if the split collet is in the unclamped state, the locking portion of the drop prevention means has the hollow taper shank. The engagement with the jaws prevents the tool holder from falling off the spindle.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view in which the tip of a main shaft of a machine tool such as a machining center is cut along a plane including a center axis of the main shaft indicated by a dashed line, and more specifically, a cross-sectional view taken along a line II in FIG. It is a figure which mainly shows the split collet which clamps the tool holder of this invention. FIG. 2 is an enlarged cross-sectional view taken along line II-II of FIG. 4, showing a split collet for clamping the tool holder on the right side of the center axis and a tool holder preventing means on the left side of the center axis. It is. FIG. 3 shows a modification of the drop-off preventing means in FIG. FIG. 4 is a cross-sectional view in which the front end of the main shaft is cut along a plane perpendicular to the central axis of the main shaft, and more specifically, is a cross-sectional view along the line IV-IV in FIG. 1 to 3
, The direction of the center axis of the main shaft is defined as the Z-axis direction, and the vertical and horizontal directions are defined based on the positional relationship shown in the figure.

The main shaft 14 of the machine tool includes a bearing 16
a, 16b and other bearings (not shown) rotatably supported inside the housing 10. The bearings 16a, 16b include a plurality of sleeves 18a, 18b,
It is held at a predetermined position by 18 c and 18 d and the bearing retainer 12. A tapered hole 14 a is formed at the tip of the main shaft 14. The tapered hole 14a is provided such that the center axis thereof coincides with the center axis of the main shaft. The main shaft 14 is further formed with a central hole 14d penetrating in the longitudinal direction from the rear end of the main shaft 14 to the tapered hole 14a. The center hole 14d is also arranged such that its center axis coincides with the center axis of the main shaft. Center hole 14d
Is provided with a draw bar 22 extending in the longitudinal direction. The draw bar 22 is also arranged such that its central axis coincides with the central axis of the main shaft. Drawbar 22
Are operably supported by the sleeve 26 in the vertical direction along the Z axis. In FIG. 1, the left side with respect to the center axis of the main shaft 14 shows a clamp state in which the draw bar 22 is pulled up, and the right side shows an unclamped state in which the draw bar 22 is pulled down. Figures 2 and 3
Shows a clamp state in which the drawbar is raised.

In the main shaft 14, a shoulder 14b is provided between the center hole 14d and the tapered hole 14a so as to protrude inward in the radial direction and extend in the circumferential direction. A taper ring 30 is disposed above the shoulder 14b, and the taper ring 30 is supported by the shoulder 14b via a ring 33 or a disc spring retaining ring 34. A locking portion 30a is formed on the inner peripheral side of the upper end of the tapered ring 30. The sleeve 26 is fitted so as to be in contact with the inner peripheral surface of the center hole 14d of the main shaft 14, supports the draw bar 22, and presses and fixes the taper ring 30 from above, as described above.

A tool holder 20 of a two-face constrained type, particularly a tool holder 20 having a hollow taper shank such as an HSK shank is mounted on the tip of the main shaft 14 via the tapered hole 14a. That is, the tool holder 20 is provided with the tapered hole 1 of the main shaft 14.
4a and the lower end surface 14c. The tool holder 20 has a holding groove 20a. Tool holder 2
Reference numeral 0 denotes a gripper (not shown) of an automatic tool changing device (not shown) engaged in the holding groove 20a, and a mounting position of the tool holder 20 shown in the drawing and a magazine (not shown) of the automatic tool changing device. The new and old tool holders are exchanged by moving the tool holder 20 to and from the storage position (1). Further, the tool holder 20 has a hollow tapered shank 20b. The outer peripheral surface of the hollow tapered shank 20b has a tapered hole 1
4a. On the inner surface of the hollow taper shank 20b, a jaw 20d is formed which engages with a locking portion 28b at the tip of a pair of holding levers 28 as a drop-off preventing means. The jaw 20d is a hollow taper shank 2
0b extends in the circumferential direction at a predetermined height of the inner peripheral surface.

A substantially cylindrical pin 20e is provided inside the hollow tapered shank 20b so as to extend upward along the Z axis. The pin 20e is a hollow taper shank 2
0b is fixed to the bottom surface. On the other hand, a collet driver 24 is attached to the tip of the draw bar 22.
The collet driver 24 is a substantially columnar member, and has a hole 24b for the pin 20e at the lower end and a mounting screw hole 24c for the drawbar 22 at the upper end along the central axis. The collet driver 24 is attached to the tip of the draw bar 22 by screwing so that the collet driver 24 does not fall off from the tip when the draw bar 22 is pulled up. In addition, the collet driver 24
The lower end of the hole 24b is in slidable contact with the outer peripheral surface of the pin 20e, and is guided in the Z-axis direction by the pin 20e. Further, the collet driver 24 has a first pressing surface 24a formed at a peripheral portion near the lower end and a second pressing surface 24d formed at a peripheral portion at the upper end.

Next, means for preventing the tool holder from dropping off the spindle will be described with reference to FIG. A pair of holding levers 28
Is a substantially L-shaped member, and a locking portion 2
8b and a mounting portion 28a projecting outward in the radial direction at the upper end portion
And The holding lever 28 is connected to the shoulder 1 of the main shaft 14.
4b. Referring also to FIG. 3, each of the pair of holding levers 28 is opposed to the diametrically opposite side inside the main shaft 14. A pair of holding levers 28
, Two split collets 36 described later are arranged on each side. The holding lever 28 has a mounting portion 28a which is pressed against a shoulder portion 14b inside the main shaft 14 and mounted. The holding lever 28 itself is formed of a material which is easily elastically deformed, such as spring steel, and its locking portion 28b
Is mounted so as to swing in the radial direction and always engage with the jaw 20d of the hollow tapered shank 20b. The elastic force of the holding lever 28 is selected such that the locking portion 28b of the holding lever 28 can swing by the attaching / detaching force of the tool holder 20 to the main shaft 14 by the automatic tool changer.

Next, another embodiment of the means for preventing the tool holder from falling off the main shaft will be described with reference to FIG. In the embodiment of FIG. 3, the same components as those in the embodiment of FIG. 2 are denoted by the same reference numerals. A pair of holding levers 28
Is a generally L-shaped member, and a locking portion 28
b, and a mounting portion 28a protruding radially outward at the upper end. The holding lever 28 is provided on the shoulder 14 of the main shaft 14.
b. Referring to FIG. 3, each of the pair of holding levers 28 is opposed to the diametrically opposite side inside the main shaft 14. On each side of the pair of holding levers 28, two split collets 36, which will be described later, are provided. The holding lever 28 is arranged such that the mounting portion 28 a passes through the opening of the disc spring holding ring 34 and protrudes from the inside of the disc spring holding ring 34 to the outside. A disc spring 32 as an urging means is disposed between the mounting portion 28a and the shoulder 14b. The mounting portion 28a
It is urged upward from below by a disc spring 32,
As a result, the holding lever 28 is moved to the locking portion 28 at the tip thereof.
b is urged to open outward toward the jaw 20d of the hollow tapered shank 20b.

As described above, two split collets 36 are provided on both sides of the pair of holding levers 28, respectively.
More specifically, the split collet 36 is disposed on a predetermined circumference centered on the central axis of the main shaft 14 and having a radius between the central axis and the holding lever 28 as a radius. The split collet 36 is a substantially I-shaped member, and is provided so as to extend in the longitudinal direction of the main shaft 14. The split collet 36
The jaw 20 of the hollow tapered shank 20b is provided on the outside near the lower end.
d and a second locking portion 36 for the locking portion 30a of the tapered ring 30 on the outer side on the upper end side.
b, a first receiving surface 36d for the first pressing surface 24a of the collet driver 24 inside the vicinity of the lower end, and a second receiving surface 24d of the collet driver 24 inside the upper end side. And a second receiving surface 36c. Split collet 3
The sixth first locking portion 36a is provided so as to engage with the jaw 20d of the hollow tapered shank 20b when the draw bar 22 is pulled up. Split collet 3
The sixth second locking portion 36b is provided so as to engage with the locking portion 30a of the tapered ring 30 when the draw bar 22 is pulled up. The first receiving surface 36d of the split collet 36 is provided so as to engage with the first pressing surface 24a of the collet driver 24 when the draw bar 22 is pulled up. The second of the split collet 36
Nest surface 36c of, when the draw bar 22 is pulled, is provided to engage with the second press-contact surface 24 d of the collet driver 24. Spring 37 is collet 36
At the upper end in the circumferential direction. The spring 37 acts to urge the collet 36 to always contract.

Hereinafter, the operation of the embodiment of the present invention will be described.
First, when an automatic tool changer (not shown) of a machine tool starts a tool changing operation, the magazine (not shown) executes an indexing operation to perform a desired operation from a plurality of tools stored in the magazine. A tool (not shown) is selected. As described above, the tool is mounted on the tool holder 20 and is held by the gripper (not shown) of the tool changing device in the holding groove 20a of the tool holder 20. Next, the tool changer places the selected tool and the tool holder 20 directly below the main shaft 14, and inserts the hollow tapered shank 20 b of the tool holder 20 into the tapered hole 14 a of the main shaft 14.
When the hollow tapered shank 20b is inserted into the tapered hole 14a, the upper end of the hollow tapered shank 20b is
Between the inner peripheral surface of the tapered hole 14a and the holding lever 28, and the holding lever 28 urged radially outward.
Are pushed radially inward. As a result, the interval between the tapered hole 14a and the holding lever 28 is widened, and the hollow tapered shank 20b can enter further.

The hollow taper shank 20 of the tool holder 20
When b is further inserted, the hollow taper shank 20
b contacts the inner surface of the tapered hole 14a,
The flange end surface 20c of the tool holder 20 contacts the lower end surface 14c of the spindle 14. As a result, the insertion operation of the hollow tapered shank 20b is stopped, and the tool holder 20 is supported by the tapered hole 14a of the main shaft 14 and the lower end surface 14c. At this time, the lower end side of the holding lever 28 is urged radially outward by the elasticity of itself or the elasticity of the disc spring 32, and the locking portion 28b is
With the jaw 20d. Thereby, the tool holder 20
Is temporarily fixed to the tip of the spindle 14. At this point, the automatic tool changer can separate from the main shaft 14 and release the engagement with the tool holder 20. Before the tool holder 20 is clamped, the automatic tool changer can be separated from the main shaft 14, so that the time required for tool change can be reduced.

Next, the draw bar 22 is pulled upward along the Z axis. Thereby, the collet driver 2
4 is engaged with the first receiving surface 36d of the split collet 36, and the second pressing surface 24d of the collet driver 24 is engaged with the second receiving surface of the split collet 36. Engage with surface 36c. At this time, the split collet 36 is pressed radially outward by the collet driver 24, the first locking portion 36a engages with the jaw 20d of the hollow taper shank 20b of the tool holder 20, and Locking part 36
b engages with the locking portion 30 a of the tapered ring 30. Thus, the tool holder 20 is completely mounted in the tapered hole 14a of the main shaft 14.

When removing the tool holder 20 from the spindle 14, first, the automatic tool changer starts the approach operation to the spindle 14. Next, the draw bar 22 is moved down along the Z axis. Thereby, the engagement between the collet driver 24 and the split collet 36 is released. At this point, the holding lever 28 can be moved by its own elasticity or by the disc spring 3
Due to the elasticity of 2, the distal end is urged radially outward, so that the engaging portion 28b of the holding lever 28 and the jaw 20d of the hollow taper shank 20b of the tool holder 20 are engaged. Thereby, the tool holder 20 maintains the state temporarily fixed to the main shaft 14. Therefore, the tool holder 20 does not fall off. Next, the gripper of the automatic tool changer engages with the holding groove 20a of the tool holder 20 to hold the tool holder 20, and the tool holder 20 is withdrawn downward along the Z axis. At this time, the holding lever 28 is pushed radially outward by the hollow tapered shank 20b that moves downward against the urging force of the disc spring 32. This allows the hollow taper shank 20b to pass below. As described above, since the tool holder 20 can be unclamped before the gripper of the automatic tool changer grips the tool holder 20, the time required for tool change can be reduced as compared with the conventional tool holder mounting device. It can be shortened.

[0020]

As is apparent from the above description, the present invention provides a tool holder mounting device provided with a drop-off preventing means for temporarily fixing a tool holder of a hollow tapered shank to a tapered hole at the tip of a spindle. The tool holder mounting device according to the present invention, when changing the tool of the tool holder of the hollow taper shank,
This has the effect of preventing the tool holder from falling off. Since the falling-off preventing means is provided substantially parallel to the split collet in the gap between the split collets, it is not necessary to form a through-hole in a direction perpendicular to the axis line to the main shaft unlike the related art. Does not worsen.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along a line II of FIG. 4, showing a tool holder mounting device of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG. 4, showing a split collet for clamping a tool holder and a means for preventing the tool holder from falling off according to the present invention.

FIG. 3 is a cross-sectional view showing a modification of the drop-off preventing means of FIG.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Housing 14 ... Spindle 14a ... Tapered hole 14c ... Spindle end surface 20 ... Tool holder 20b ... Hollow taper shank 20c ... Flange surface 20d ... Jaw part 22 ... Drawbar 24 ... Collet driver 28 ... Holding lever 28b ... Locking part 32 ... Plate Spring 36: Split collet

Claims (3)

(57) [Claims] We claim: 1. Insert the hollow taper shank of the tool holder in the tapered hole of the spindle, with contacting the outer surface and the inner surface of the tapered bore of the hollow taper shank, a flange surface of the tool holder of the spindle in the tool holder mounting device is brought into contact with the end surface attaching the tool holder to the spindle, and a jaw portion formed in a tapered shape in the circumferential direction of the inner surface of the hollow tape path shank of the tool holder, the tapered bore of the spindle behind the provided inside, engaging the jaws of the tool holder is inserted into the tapered hole in scaled radially and split collet disengaged, is inserted inside the spindle in the axial direction of the spindle Engages the inside of the split collet by moving to
A collet driver for expanding the split collet, a drawbar inserted coaxially with the collet driver inside the main shaft to move the collet driver forward and backward in the axial direction of the main shaft, and a gap in a circumferential direction of the split collet. At least two opposite
One provided, before the hollow taper shank of the tool holder
When inserted into the tapered hole of the serial spindle holding lever having an engagement portion engaged with the oscillating motion to the jaws of the tool holder
And the collet driver and drawbar of the spindle
The holding lever is provided between the insertion hole and the holding lever.
The jaw of the tool holder is used to lock the bar against the swinging motion of the bar.
With an elastic biasing member that constantly elastically biases outward toward
Tool holder mounting apparatus characterized by comprising a disengagement prevention means comprising, a. 2. The drop-off prevention means is attached to a circumferential gap of the split collet, and is capable of engaging and disengaging the jaw and the locking portion by a detaching force of the tool holder to a main shaft. The tool holder mounting device according to claim 1, comprising a holding lever having: 3. The drop-off preventing means includes the retaining portion, a retaining lever provided in a circumferential gap of the split collet, and a retaining portion of the retaining lever always facing the jaw. 2. The tool holder mounting device according to claim 1, further comprising an urging means for elastically urging.