JPH02224907A - Holding device for tool holder - Google Patents

Abstract

PURPOSE:To prevent accident of a tool holder falling prior to its holding by an exchange arm in changing a tool by releasing the engagement of a tapered hole and tool holder by pressing by a push rod and holding it provisionally after receiving the tool holder by a holding member. CONSTITUTION:When a push rod 5 is pressed, a steel ball 10 is struck to the rear face inclined part of a pull stud 9 and in case of any biting between a tapered hole 4 and taper shank part 8a, a slight elastic deformation is caused on the push rod 5 and when the pressing force exceeds the biting force, an impact like push force is caused and the pull stud 9 is pushed downward vigorously. A steel ball 7 is still engaged with an interference position holding face 15a and the pushed tool holder 4 is received by the steel ball 7 at the pull stud 9 front face and no impact force is acted on a temporarily holding pin 12. The steel ball 10 descends the inclined face to a clearance groove 16, a push rod 5 descends as well and on the way of the steel ball 6 being descended on the inclined face 15C of a step part 15 the pull stud 9 is temporarily held by being received by the temporarily holding pin 12. With the further descent of the push rod 5 the steel ball 7 is engaged with a flank 15b and unclamping is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tool holder holding device for mounting a tool holder on the main shaft of a machine tool such as a machining center that is equipped with an automatic tool changer.

BACKGROUND OF THE INVENTION Conventionally, when changing a tool in a machining center, the tool holder is held by a tool changing arm and then unclamped, which takes a long time.

Therefore, Utility Model Application No. 62-138513 and Japanese Patent Application Publication No. 63-52
No. 942 is equipped with a temporary holding mechanism 114 that elastically engages with the tool holder 108, as shown in FIG.
It has been proposed that even if the tool holder 108 is unclamped, the tool holder 108 is held by a temporary holding mechanism 114 to prevent it from falling, thereby shortening the tool exchange time.

Problems to be Solved by the Invention According to the above, the push rod 105 in the main shaft 102 is provided with the pushing surface 105b that pushes the rear end of the tool holder 108, and when unclamping, the push rod 105 is forcibly moved forward. By the time of extrusion, the tool holder 10
The gripping device (steel ball) 107 at the tip of the push rod 105, which had been in a clamped state, is now located outside the movement path of the pull stud 109 of the tool holder 108. Therefore, when the taper shank portion 108a of the tool holder 108 is fitted very snugly into the taper hole 104 at the tip of the spindle, the pressing surface 105b of the push rod 105 is pushed against the pull stud 109 by the mutual engagement of the taper surfaces. At the beginning of pressing , the fitted state may not be released. Then, push rod 105
cannot move forward (downward) from the state shown in FIG. 5, during which the push rod 105 undergoes slight elastic deformation, and at the moment the pushing force by the push rod 105 exceeds the clamping force, the push rod 105 elastically deforms. is released, and the pull stud 109 is pushed forward forcefully by an impactful pushing force, and as a result, the pull stud 109 is moved to the temporary holding mechanism 114.
There is a problem in that the tool holder 108 may fall from the spindle 102 due to the tool holder 108 climbing over the main shaft 102 .

The object of the present invention is to provide a tool holder holding device for a main spindle that includes a temporary holding mechanism on the main spindle as described above.

An object of the present invention is to provide a holding device that prevents a tool holder from falling.

Means for Solving the Problems The present invention provides a tool holder holding device for a spindle having a temporary holding mechanism, in which the stroke required for a push rod to push out a tool holder and release the fitted state from a tapered hole is shortened. The tool holder is characterized in that during this stroke movement, the gripping member at the tip of the push rod is located within the movement path of the pull stud of the tool holder.

Effect According to the above configuration, even when the fitted state is released, the gripping member at the tip of the push rod is still within the movement path of the pull stud of the tool holder, so that =3- the tool holder is in the released state. In this case, the grip member is engaged with the holding member before the temporary holding mechanism is engaged with the holding member. Therefore, even if the tool holder gets stuck, the impact force will not directly act on the temporary holding mechanism via the pull stud, and the tool holder will not fall.

First Embodiment In FIG. 1, a main shaft 2 is rotatably supported by a main shaft head 1. As shown in FIG. A guide hole 3 is passed through the main shaft 2 at its center. The tip of the guide hole 3 is formed into a tapered hole 4 for fitting a tool holder. A push rod 5 extending in the axial direction is inserted through the guide hole 3 so as to be freely movable in the axial direction, and is biased rearward by a countersunk spring 6. push rod 5
Four steel balls 7, which are illustrated as gripping members, are attached to the tip of the gripper so as to be movable in the radial direction. A pushing steel ball 10 is mounted axially rearward of the steel ball 7 at a position that creates a predetermined gap between the pull stud 9 of the tool holder 8 and is movable in the radial direction, facing the steel ball 7. be. Further, an axial slit 11 is formed at the tip of the push rod 5, and a temporary holding pin 1 that is movable in the radial direction is inserted into the slit 11.
2 is biased radially inward by a spring 13 to constitute a temporary holding mechanism 14 that elastically engages with the pull stud 9 of the tool holder 8.

On the other hand, a stepped portion 15 is formed in the guide hole 3 in correspondence with the steel ball 7, and this stepped portion 15 has a small diameter interference position holding surface 15a and a large diameter flank surface as shown in FIG. 15b, and the two are connected by an inclined surface 15c. When the steel ball 7 engages with this interference position holding surface 15a, the steel ball 7 projects into the axial movement path of the pull stud 9 of the tool holder 8,
When the steel ball 7 engages with the flank 15b, it is removed from the movement path of the pull stud 9. Also.

Corresponding to the pushing steel ball 10, an annular relief groove 1 is provided in front of the pushing steel ball 10 in the state shown in FIG. 1 showing the clamped state.
6 is formed, and the width of this relief groove 16 is the same as that of the pushing steel ball 10.
After pushing the pull stud 9 to release the engagement with the taper hole 4 of the tool holder 8, the pushing steel ball 10 moves as shown in FIG. 3(c).
The steel ball 7 starts to enter the relief groove 16 as shown in FIG.
The width is set to within 6. and,
The push rod 5 is moved from its clamped position (position A of the pushing steel ball 10 in FIG. 3(a) or FIG. 3(c)) to the position where it is released from the tapered hole 8a of the tool holder 8 (the third position). The stroke ST required to reach the position B) of the pushing steel ball 10 in FIG. 3(c) (FIG. 3(c)) is calculated as follows:
During this period, the steel ball 7 is engaged with the interference position holding surface 15a. This means that the stroke ST
is set to be approximately the same as the distance between the contact point 15d between the steel ball 7 at the clamp position and the interference position holding surface 15a and the intersection 15e (FIG. 3(C)) between the interference position holding surface 15a and the inclined surface 15c. You can also say that it is. And temporary holding mechanism 1
4 is a position where the steel ball 7 does not yet engage with the front surface of the pull stud 9 when it reaches the intersection 15e, that is, the intersection 1
The center line of the tip of the temporary holding pin 12 is positioned slightly below the height position corresponding to 5e.

Next, the effect will be explained. In FIG. 3(,), the pull stud 9 is pulled toward the rear of the spindle by the steel ball 7 engaged with the interference position holding surface 15a, and the tool holder 8 has its tapered shank portion 8a fitted into the tapered hole 4. ing. When a tool change command is issued, an unclamp cylinder (not shown) behind the main spindle 2 acts to push the push rod 5 against the disk spring 6. Then, the pushing steel ball 10 comes into contact with the rear inclined portion of the pull stud 9 (FIG. 3(b)). At this time, if there is a jam between the taper hole 4 and the taper shank portion 8a of the tool holder 8, the push rod 5 cannot move forward as shown in FIG. 3(b), causing slight elastic deformation. push rod 5
When the pushing force exceeds the sticking force, an impactful pushing force occurs. As a result, the pull stud 9 is forcefully pushed downward, but since the stroke of the push rod 5 up to this point is the stroke ST, the steel ball 7 is still at the interference position holding surface 1.
The tool holder 4, which is engaged with the tool holder 5a and pushed vigorously, is stopped by the steel ball 7 on the front surface of its pull stud, and no direct impact force is applied to the temporary holding pin 12. At this time, the pushing steel ball 10 has begun to descend down the slope toward the relief groove 16 (FIG. 3(C)). When the fitted state with the taper hole 4 was released in this way, the push rod 5 further descended and the steel ball 7 was stopped on the way down the inclined surface 15c of the stepped portion 15. Pull stud 9 is now temporary holding pin 1
2, the receiver is stopped and temporarily held. Then, in this state, the push rod 5 is further lowered and the steel ball 7 is moved to the flank 15b.
and completes unclamping (Fig. 3(d)).

Next, the V-groove 8b of the tool holder 4 is gripped by a tool exchange arm (not shown), and the tool holder 4 is immediately moved in the axial direction to remove the tool holder 4 from the spindle 2. At this time, the pull stud 9 moves the temporary holding pin 12 radially outward against the spring force.

Also, when inserting the tool holder 4, if the tool holder 4 is temporarily held in the temporary holding mechanism 14, when unclamping is completed (see Fig. 3)
In d)), there is a sufficient axial distance between the front surface of the pull stud 9 and the steel ball 7, and when the push rod 5 is retracted, the steel ball 7 engages with the pull stud 9 after reaching the interference position holding surface 15a. Clamping of the pull stud 9 is performed reliably in a conventional manner.

In this example, after the pushing steel ball was used to release the fitted state between the taper hole and the taper shank, the pushing steel ball was released in the radial direction. is not forcibly pushed further, and the tool holder is locked with the temporary holding mechanism immediately after unclamping, so the tool holder does not protrude significantly from the spindle when unclamping is completed, and the gap between it and the taper hole is reduced. It has the advantage that it can be made smaller and the tool holder has less wobbling when changing tools.

A second embodiment in which no steel balls are used in FIG. 4 will be described. Components that are the same as those in the first embodiment are given the same numerals, and their explanations will be omitted. There is a pull stud 9 at the tip of the push rod 5.
A hole 5a into which the pull stud 5 enters is formed, and a bottom surface 5b of the hole 5a constitutes a pressing surface of the pull stud 5. In the clamped state (FIG. 4(a)), there is a slight gap between the rear end surface of the pull stud 9 and the push rod 5. The distance between the contact point 15d of the steel ball 7 in the clamped state with the interference position holding surface 15a and the intersection 15e of the interference position holding surface 15a and the inclined surface 15c of the stepped portion 15 is determined by The pressing surface 5b is
The stroke ST is set to be the same as the stroke ST required to push the pull stud 11 and release the fitting between the tool holder 8 and the spindle taper hole 4. The temporary holding mechanism 14 is installed so that the center of the tip of the temporary holding pin 12 is located at approximately the same height as the center of the steel ball 7 when unclamping is completed (FIG. 4(C)).

Also in this embodiment, the push rod 5 pushes the pull stud 9, and the taper hole 4 and the taper shank 8a of the tool holder 8
The case where the tip is stuck means that, as in the previous embodiment, an impactful pushing force is applied to the pull stud 9 due to the elastic deformation of the push rod 5, etc., but when the fitted state (sticking) is released (the fourth In Figure (b)), the stroke of the push rod 5 is the stroke ST, and the steel ball 7 is still on the interference position holding surface 15a, so the front surface of the pull stud 9 is stopped by the steel ball 7. Thereafter, as the push rod 5 descends, the steel ball 7 passes through the inclined surface 15c and the flank surface 1.
5b. On the way down the slope 15C, the pull stud 9 engages with the temporary holding pin 12 and is temporarily held, and unclamping is completed in the state shown in FIG. 4(c).

In these two embodiments, a steel ball movable in the radial direction is used as the gripping device at the tip of the push rod. Needless to say, it can also be applied to a collet-type device using a gripping member having spring properties. The push rod pushes the tool holder to release the fitted state between the taper hole and the taper shank portion of the tool holder, and then the tool holder is stopped by the gripping member and then held by the temporary holding mechanism. As a result, the fit between the taper hole and the taper shank is extremely good, and even if there is a sticking condition, an impactful pushing force may be generated due to the release of the elastic deformation of the push rod, etc. This pushing force is stopped by the gripping member on the interference position holding surface, and can be prevented from directly acting on the temporary holding mechanism. Therefore, even if the pull stud of the tool holder is pushed out forcefully by the pushing force, it will not get over the temporary holding mechanism, and when changing tools, the tool holder must be unclamped before being gripped by the tool changing arm. This also prevents the tool holder from falling and allows tools to be replaced quickly and reliably.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the device of the present invention, and Figure 2 is from ■-■ in Figure 1.
3 is an enlarged cross-sectional view, FIG. 3 is an explanatory diagram of the operation, FIG. 4 is another embodiment, and FIG. 5 is a conventional technique. 2. Main shaft, 3. Guide hole, 4. Tapered hole, 5.
... Push rod, 7... Gripping member, 8... Tool holder, 9... Pull stud, 10... Steel ball for pushing, 14... Temporary holding mechanism, 15... Step part, 15a...
・Interference position holding surface, = 12

Claims (1)

[Claims] 1. A push rod capable of pushing out the tool holder is inserted into the guide hole of the spindle, which has a tapered hole at the tip into which the tool holder fits, so that it can move freely in the axial direction, and the gripping member is moved in the radial direction at the tip of this push rod. an interference position holding surface that engages with the gripping member and projects the gripping member into the movement path of the pull stud of the tool holder; In the tool holder holding device, the main shaft is provided with a temporary holding mechanism that elastically engages with the tool holder after the tool holder and the tapered hole are released from the fitted state. The stroke required for the push rod to push out the tool holder and release the fitted state with the tapered hole is set such that the gripping member is engaged with the interference position holding surface during this stroke movement. Characteristic tool holder holding device.