JP2001150260A - Machining center - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the accuracy for the position of the rotational axis of a main spindle by minimizing deflection of a main spindle head and roller guides even if moment forces are increased when a cutting speed is increased or when the amount of cutting is increased. SOLUTION: This machining center includes a main spindle head fixing part 4 fixed to a machining center body, the main spindle head 2 vertically movably held against the main spindle head fixing part 4, and the main spindle 1 held against the main spindle head 1 in such a way as to be rotatable about a vertical axis. The roller guides 3 for movably holding the main spindle head 2 are positioned between the main spindle fixing part 4 and the main spindle head 2 and in positions that are in symmetry with respect to the rotational axis of the main spindle 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining center used for machining machine parts and the like.

[0002]

2. Description of the Related Art The conventional technology is VM4 of Hitachi Seiki
0II catalog (VM40II--9405 / 03), and its configuration will be described with reference to FIG.

A spindle head fixing portion 22 is fixed to an upper portion of a main body 21 of the machining center. Inside the spindle head fixing portion 22, a spindle head 24 is provided with two roller guides 23 interposed therebetween. It is provided so as to be movable in the Z direction (vertical direction of the machining center) which is a vertical direction. The two roller guides 23 include a spindle head 24
Two guide rails 23a extending in the Z direction and arranged in parallel on one side surface of the
And a track 23b which is fixed to the inner side surface and is fitted to the two guide rails 23a.

The spindle head 24 has a nut 27 screwed to a ball screw 26 extending in the Z direction.
The drive shaft of a Z-axis servo motor (not shown) fixed to the spindle head fixing part 22 is connected to the ball screw 26 via a belt (not shown), and the rotation of the Z-axis servo motor is To the spindle head 24
Is movable up and down. A spindle 25 rotated by a rotating means (not shown) is held on the tip end side of the spindle head 24. The spindle 25 has a chuck (not shown) for gripping a blade (not shown) at the tip. They can be moved up and down together.

[0005]

In the machining center disclosed in the prior art, since the axis of rotation of the main shaft 25 and the line of action of the roller guide 23 are offset, a force is applied to the blade attached to the main shaft 25 during cutting. And spindle 2
A moment force in the direction opposite to the rotation direction of No. 5 is generated. At this time, if the cutting speed is high or the cutting amount is large, the moment force increases, and the spindle head 24 or the spindle head 2
There is a problem in that the two roller guides 23 supporting the spindle 4 on the spindle head fixing portion 22 are bent, and it becomes impossible to ensure the accuracy.

Further, the spindle head 24 undergoes a slight thermal deformation due to the heat of the spindle 25 and the like, but cannot be deformed in the mounting direction of the roller guide 23 during this deformation.
There is also a problem that it is difficult to ensure the accuracy due to the influence of the direction in which the thermal deformation of the spindle head 24 is biased, particularly the direction opposite to the side where the roller guide 23 is mounted. For example, the spindle 25
There is a problem that the position of the rotation changes and the rotation axis shifts.

The present invention has been made in view of the above-mentioned problems of the prior art, and the spindle head and the roller guide bend even if the cutting force is increased or the moment force is increased when the cutting amount is increased. It is an object of the present invention to provide a machining center capable of minimizing the size and ensuring the accuracy of the rotational axis position of the main shaft.

[0008]

In order to solve the above-mentioned problems, a machining center according to a first aspect of the present invention has a spindle head fixing portion fixed to a machining center main body, and is held by the fixing portion so as to be vertically movable. In a machining center having a main spindle head and a main spindle rotatably held about a vertical axis on the main spindle head, guide means for movably holding the main spindle head are symmetrical with respect to the rotation axis of the main spindle. At a position, it is arranged between the spindle head fixing portion and the spindle head.

A machining center according to a second aspect of the present invention is the machining center according to the first aspect, wherein a side surface of the spindle head fixing portion on which the guide means is disposed is provided so as to be movable toward the spindle head. Preload adjusting means for moving and adjusting the preload of the guide means is provided.

That is, in the machining center according to the first aspect of the present invention, the guide means for movably holding the spindle head is disposed at a position symmetrical with respect to the rotation axis of the spindle, and the spindle is driven by heat transmitted to the spindle head. The head is deformed evenly, the moment force acting on the guide means is evened, and the position accuracy of the rotation axis of the main shaft is secured.

In the machining center according to a second aspect of the present invention, the side surface on which the guide means is disposed of the spindle head fixing portion is moved by preload adjusting means capable of moving toward the spindle head. The preload of the guide means is adjusted to increase the rigidity of the guide means.

[0012]

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. 1 is a top view around the machining center Z axis, FIG. 2 is a front view around the Z axis, and FIG. 3 is a side view around the Z axis.

The spindle 1 has a tip end projecting from the tip of the spindle head 2 and is rotatably held in the spindle head 2 by a bearing such as a ceramic bearing. The main shaft 1 is a built-in type main shaft having a spindle unit (not shown) and a motor unit (not shown) inside, and is rotated by a motor mounted inside. Therefore, when the main shaft 1 is rotated, heat generated from the motor in the main shaft 1 and heat generated from the bearings are generated. A mounting portion (not shown) for mounting a cutting tool (not shown) such as a cutting tool is provided at a tip of the spindle portion.

The spindle head 2 has a square pillar shape.
Its cross-sectional shape is symmetrical with respect to the rotation axis of the main spindle 1, and the center line of the main spindle head 2 and the rotation axis of the main spindle 1 are the same. The spindle head 2 is supported in a spindle head fixing portion 4 with a roller guide 3 interposed therebetween, and is movable vertically (Z direction) along the rotation axis of the spindle 1.

The spindle head fixing portion 4 has a hollow square shape so as to surround the side surface of the spindle head 2, and members 4a, 4a, and 4a forming four sides of the square shape, that is, four side surfaces.
4b, 4b are made of separate iron plates, and the member 4a and the member 4
b is fixed using bolts 11, and the members 4a and 4a
The member 4b and the member 4b are assembled in a square shape so as to face each other. Further, at the upper end (upper side in FIGS. 2 and 3) of the spindle head fixing portion 4, the top plate 10 is fixed to the end surfaces of the members 4 a and 4 b using bolts 12 so as to cover the upper part of the spindle head 2. . The spindle head fixing portion 4 is fixed to a machining center body (not shown).

A predetermined gap is provided between each side surface of the spindle head 2 and each member 4a, 4b of the spindle head fixing portion 4, and guide means is provided between the members 4a, 4a and the side surface of the spindle head 2. Roller guides 3 are provided symmetrically with respect to the main shaft 1. That is, the roller guide 3 is provided between the spindle head fixing portion 4 and the spindle head 2 at a position symmetrical with respect to the rotation axis of the spindle 1 (the center line of the spindle head 2), and the member 4a and the spindle head 2 are provided. A pair of roller guides 3 are provided in each of the spaces therebetween.

The roller guide 3 comprises a guide rail 3a and a track 3b fitted to the guide rail 3a. The pair of guide rails 3a is fixed to the side surface of the spindle head 2 by bolts extending in the Z direction. The track 3b is fixed to the inner side surface of the member 4a of the spindle head fixing section 4 with bolts at the same height in the Z direction. The two tracks 3b are fitted to each guide rail 3a vertically.

The spindle head 2 is moved up and down by the power of a servomotor 5 fixed on the top plate 10 of the spindle head fixing section 4. The drive shaft of the servomotor 5 has a ball screw 6
Are directly connected via a coupling 9. The ball screw 6 extends in the Z direction and is introduced into the spindle head fixing portion 4, and is rotatably supported by a support unit 8 fixed to one inner surface of the member 4 a of the spindle head fixing portion 4. , Which is screwed to a nut 7 fixed to a side surface of the spindle head 2 near the upper side.

The nut 7 is fixed at the center between a pair of guide rails 3a fixed to one side surface of the spindle head 2. That is, one servo motor 5 is provided above the center position between the pair of roller guides 3, and the ball screw 6 extends in the Z direction at the center position. As shown in (1), it is located on a line passing through the rotation axis of the spindle 1 (the center line of the spindle head 2).

The operation of the first embodiment having the above configuration will be described with reference to FIGS. 1, 2 and 3. FIG. When a tool (not shown) is attached to the tip of the spindle 1 to process a work (not shown), the cutting resistance of the tool is applied to the spindle head 2 and the roller guide 3 as a moment force. When the moment force is increased, the spindle head 2 and the roller guide 3 are bent by the moment force. At this time, by arranging the roller guide 3 symmetrically with respect to the rotation axis of the spindle 1 on the spindle head 2 having a symmetrical shape, the amount of deflection becomes uniform in all directions, and the amount of deflection increases in only one direction to ensure accuracy Will not be difficult. Further, by disposing the four roller guides 3, the force applied to the roller guides 3 is dispersed, and the bending of the roller guides 3 is reduced.

When the workpiece is cut by the cutting tool, the main shaft 1 rotates, and heat is generated from a motor and a bearing (not shown) housed in the main shaft 1. This heat is sufficient to thermally deform the spindle head 2 by a very small amount, and it is difficult for a high-precision processing machine to ensure accuracy even with a small thermal deformation due to heat.

At this time, the spindle head 2 having a symmetrical shape with respect to the rotation axis of the spindle 1 has a structure in which heat from a motor or a bearing in the spindle 1 gradually affects the rotation from the rotation axis of the spindle 1. , Uniformly undergoes thermal deformation. Then, although the spindle head 2 itself thermally expands, the heat spreads around the rotation axis of the spindle 1, so that even if the spindle head 2 thermally expands, the position of the rotation axis of the spindle 1 does not change. That is, in the spindle head 2, the deformation in the vertical direction in which the roller guide 3 is disposed in FIG. 1 is the same around the rotation axis of the spindle 1,
In addition, since the deformation in the left-right direction is the same around the rotation axis, the position of the rotation axis of the main shaft 1 does not move.

Further, since the roller guide 3 is arranged symmetrically with respect to the rotation axis of the spindle 1, the spindle head 2
Even if the roller guide 3 is thermally deformed by the heat transmitted to the roller guide 3, the position of the rotation axis of the main shaft 1 does not change.

Assuming that the rigidity of the main body of the machining center (not shown) and the spindle head fixing portions 4 and 24 are the same as in the prior art. If this is different, it will not be possible to make an accurate comparison of the part that is being compared this time. In addition, the spindle 1,
Assume that the stiffness and structure of 25 are similar.

According to the machining center of the first embodiment of the present invention, by disposing the roller guide 3 symmetrically with respect to the rotation axis of the main shaft 1, it is possible to uniformly receive the moment force in all directions. In addition, the number of roller guides 3 is increased to reduce the moment force applied to each roller guide, and the cutting speed is increased. It can be minimized and accuracy can be ensured. Furthermore, since the spindle head 2 and the roller guide 3 are symmetrical with respect to the rotation axis of the spindle 1, the heat from the spindle 1, which is a heat source, is transmitted uniformly and thermally deformed. The displacement can be minimized and the accuracy can be ensured.

(Embodiment 2) Embodiment 1 of the present invention will be described with reference to FIG. FIG. 4 is a top view around the machining center Z axis. The description of the same configuration as in the first embodiment is omitted.

The spindle head fixing portion 4 includes two side plates 1
4 and a track plate 15 and a reference plate 16 respectively. The reference plate 16 and the two side plates 14 are fixed using bolts 11 and the track plate 15 is fastened to the two side plates 14 by screws. Attach with 17 and track plate 15
And the reference plate 16 face each other to form a hollow square shape.

A long hole (not shown) for inserting a tightening screw 17 is formed in the side plate 14 so as to be long in the vertical direction in FIG. 4. The track plate 15 can be moved in the direction of the reference plate 16 by loosening the fastening screw 17 so that its end face is in contact with the inner surface of the side plate 14.

On the outer surface of each side plate 14, the track plate 1
L-shaped arm 1 bent so as to face the outer surface of 5
8 is fixed by a bolt 19, and a push screw 20 is screwed into the bent portion of the arm 18, and the arm 18 and the push screw 20 are configured as preload adjusting means. Set screw 20
Can move forward and backward with respect to the track plate 15, and can push the track plate 15 in the direction of the reference plate 16 at the tip thereof.

Spindle head 2, track plate 15, reference plate 1
6, roller guides 3 as guide means are arranged symmetrically with respect to the rotation axis of the main shaft 1 as in the first embodiment, and the track plate 15 and the reference plate 16 are provided with roller guides 3b. Has been fixed. Other configurations are the same as those of the first embodiment.

The operation of the second embodiment having the above configuration will be described with reference to FIG. The description of the same operation as in the first embodiment will be omitted.

The fastening screw 17 fixing the side plate 14 and the track plate 15 is loosened, and the tip of the push screw 20 is brought into contact with the track plate 15. Screw the push screw 20
The track plate 15 is moved in the direction of the reference plate 16. Then, the fastening screws 17 for fixing the side plate 14 and the track plate 15 are tightened, and the track plate 15 is
Fixed to. By doing so, the preload of the roller guide 3 increases, and the rigidity of the roller guide 3 increases.

Further, by replacing the roller guide 3 from the ball type to the roller type and bringing the roller guide 3 into line contact with the rail 3a, the rigidity can be increased.

According to the machining center of the second embodiment of the present invention, the rigidity of the roller guide 3 can be increased as compared with the first embodiment. Therefore, the deflection of the roller guide 3 can be reduced, and the position of the main shaft 1 can be secured with high accuracy.

[0035]

As described above, according to the machining center according to the first aspect of the present invention, when the cutting speed is increased or the cutting force is increased, the machining force is increased.
The deflection of the spindle head and the guide means can be minimized, and accuracy can be ensured. Further, the displacement of the spindle due to the influence of thermal deformation can be minimized, and the accuracy can be ensured.

According to the machining center according to the second aspect of the present invention, by increasing the preload of the guide means, the deflection of the guide means can be reduced and high precision can be secured.

[Brief description of the drawings]

FIG. 1 is a top view of a first embodiment of the present invention.

FIG. 2 is a front view of the first embodiment of the present invention.

FIG. 3 is a side view of the first embodiment of the present invention.

FIG. 4 is a top view of the second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spindle 2 Spindle head 3 Roller guide 3a Guide rail 3b Track 4 Spindle head fixing part 5 Servo motor 6 Ball screw 7 Nut 14 Side plate 15 Track plate 18 Arm 20 Push screw

Claims (2)

[Claims] 1. A spindle head fixing portion fixed to a machining center main body, a spindle head held by the spindle head fixing portion so as to be movable in a vertical direction, and a spindle head held by the spindle head so as to be rotatable around a vertical axis. A machining center provided with a spindle, wherein guide means for movably holding the spindle head are disposed between the spindle head fixing portion and the spindle head at positions symmetrical with respect to the rotation axis of the spindle. Machining center. 2. A side face on which the guide means is arranged of the spindle head fixing portion is provided so as to be movable toward the spindle head,
2. The machining center according to claim 1, further comprising a preload adjusting unit that adjusts a preload of the guide unit by moving the side surface.