JPS5923922B2 - Headstock - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a headstock that reduces thermal displacement.

The headstock that supports the main spindle thermally expands due to heat generation in the bearing due to rotation of the shaft, causing uneven thermal displacement in various parts of the headstock over time.

Generally, thermal displacement of the headstock of a metal processing machine moves the rotation center of the main spindle, which is directly involved in machining, and therefore machining accuracy is significantly impaired.

FIG. 1 shows an embodiment of a headstock devised to reduce the effects of thermal displacement described above.

That is, the headstock 2 bearing the main shaft 3 has a jaw portion 4a.
, 4b, and the mounting lower surfaces of the jaws 4a, 4b are located in the same horizontal plane as the spindle center 0, and the base 1
It is placed on the upper mounting surfaces 5a and 5b of.

Further, the base 1 is provided with a recessed portion in the center thereof into which the main shaft bearing portion of the headstock 2 and the like enter.

In a headstock with such a structure, each part of the headstock stretches left and right with the spindle center O as a boundary due to the heat generated by the bearings, so the spindle center O is different from the reference point R (for example, the position of the cutting edge) in Fig. 1. Do not move.

However, the heat generated in the bearing portion is transferred to the jaw portion 4a,
4b to the base 1, and the gap 7
, through the recess 6, and is indirectly propagated by radiation or the like, so that thermal displacement occurs in the base 1.

FIG. 1 shows a state in which the base 1 is displaced by ε1 in the Y direction, and the main shaft center O is also translated in the Y direction by ε1.

Therefore, in the headstock of the embodiment described above, when considering the thermal displacement of the base 1 that supports the headstock 2, the spindle center O moves with respect to the base fixing reference plane 1, which makes it possible to uniformly perform high-precision machining. As for the headstock for obtaining this, there remains a practical problem.

In consideration of the above-mentioned problems, an object of the present invention is to provide a headstock in which the movement of the spindle center relative to the reference point R and the base fixed reference plane is extremely small, no matter how much the headstock is thermally displaced due to heat generated in the bearing section. It is in.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In Figure 2, from the reference point R (for example, the position of the cutting edge)
The headstock 8, which supports a main shaft 18 at a distance r in the direction, is configured symmetrically with respect to the main shaft 18, and has jaws 9a and 9b protruding from both left and right sides.

A horizontal line connecting the jaws 9a and 9b is provided vertically above the main shaft center P and separated by a predetermined distance.

Therefore, the main shaft bearing portion projects downward in the shape of a semi-elliptic cylinder with respect to the jaws 9a, 9b.

The headstock 8 is placed on a base 14 via the jaws 9a and 9b, and in the center of the base 14, there is a space between the headstock 80 and a bearing that projects in the shape of a semi-elliptical column. In order to obtain an appropriate gap 15,
A recess 16 is provided.

Further, the base 14 has a structure that is symmetrical with respect to a vertical plane including the main axis center line, and has a mounting surface 13a for mounting the jaws 9a and 9b.

13b are respectively provided on the left and right symmetrical upper surfaces.

In addition, the headstock 8 is fixed to the base 14 evenly on the left and right sides using the pole N7b and the positioning pin 17a via the heat insulating material 11. In this case, the headstock 8 is fixed to the base 14 with an appropriate gap 15 is obtained.

Furthermore, the recess 16 of the base 14 and the headstock 8
A semicircular heat insulating material 12 is provided between the bearing part and the bearing part.

Thus, the heat generated in the headstock 8 is transferred to the heat insulating material 1.
1 and 12, and the heat propagation to the base 14 is extremely reduced.

According to the embodiment of the present invention configured as described above, the headstock 8 and the base 14 each have a left-right symmetrical structure, so that heat is evenly propagated left and right from the heat generation source of the main shaft bearing. The accompanying thermal displacement of each part of the headstock also occurs equally on the left and right sides of the center of the spindle.

Therefore, the center of the main axis does not move in the left-right direction (X direction) with respect to the reference point R.

On the other hand, the heat generated in the main shaft bearing part of the headstock 8 is
Through the insulation materials 11 and 12, the base 14 is slightly
, the upper mounting surface 13a of the base 14, 1
3b is thermally displaced upward (in the 10Y direction).

However, the main shaft bearing portion of the headstock 8 is
Since it is provided at a position h below the mounting surfaces 10a and 10b, the heat generated by the bearing section causes a thermal displacement downward (in the -Y direction) by an amount commensurate with the distance.

That is, the thermal displacement of the base and headstock is canceled out with respect to the base fixing reference 14, and the main shaft center P does not move in the vertical direction.

In this case, the distance is approximately determined by the following equation.

However, it is assumed that the headstock and base have the same coefficient of thermal expansion.

Now, looking at the above equation, it can be seen that the distance depends on the ratio of the base temperature θb and the headstock temperature θh.

That is, as the base temperature θb approaches the headstock temperature θh (the more heat is transmitted from the headstock 8 to the base 14), the distance increases and approaches the base height H.

As the distance increases, the recess 16 in FIG. 3 moves downward, and the rigidity of the base 14 decreases.

Therefore, the smaller the distance, the better.

In one embodiment of the present invention, heat insulating materials 11 and 12 are provided at the boundary between the headstock 8 and the base 14 in order to reduce heat propagation to the base 14, keep the base temperature θb low, and prevent a decrease in the rigidity of the base 14. It is provided.

In this case, the headstock temperature θh that determines the distance
Since each base temperature θb is the temperature at which the temperature gradient is stabilized (saturate temperature), the spindle center P continues to move slightly with respect to the base fixed reference plane 14' until the temperature gradient is stabilized.

FIG. 4 shows the experimental results of one embodiment of the present invention.

In the figure, ■ is the headstock displacement curve.

■ is the base displacement curve. The movement of the main shaft center P with respect to the base fixing reference plane 14' until the temperature gradient is stabilized results in a difference δ between the headstock displacement and the base displacement, which is represented by a displacement curve ■.

It has been experimentally demonstrated that the movement δ of the principal axis center P falls within 1a.

FIG. 5 shows another embodiment of the present invention, in which the headstock is mounted on a cross-boring device based on the present invention.

A base 2 vertically suspended on a column 20 and guided up and down
A spindle head 22 that is vertically symmetrical with respect to the spindle center Q is attached to the spindle head 1 .

Spindle head 22 to be attached to base 21
The mounting surfaces 23a and 23b are located at a distance to the right from the spindle center Q, and a heat insulating material 24 is provided between them and the base 21.

(As shown in the above embodiment, the spindle center Q is moved from the guide reference plane 2 due to the heat generated in the spindle head 22.
0b and the base lower surface 21a.

FIG. 6 shows another embodiment in which the headstock based on the present invention is applied to a text boring machine.

The base 31 is guided by a guide 30a of the column 30 and is movable in the vertical direction.

A spindle head 32 is fixed to the base 31 via upper mounting surfaces 35a and 35b.

The spindle head 32 has a vertically suspended main shaft, and has a symmetrical structure in the figure with the rotation center S of the main shaft as a boundary.

In addition, the lower surfaces 33a and 33b for attachment to the base 31 are located at a distance h from the spindle center S in the figure, as in the embodiment described above.
It is located above.

Furthermore, the heat insulating material 34 is connected to the base 31 and the spindle head 3.
It is provided between 2.

In this way, the spindle center S will be located at the spindle head 3.
It does not move due to the heat generated in 2.

As described above, according to the present invention, since the headstock has a symmetrical structure, the heat generated in the bearing portion of the spindle is evenly distributed on the left and right sides with the center of the spindle as the border, so thermal displacement also occurs around the center of the spindle. It occurs equally on both sides of the border.

Furthermore, the headstock (spindle head) that has the main shaft and the base that supports this headstock are equally tightened on the left and right sides with bolts and pins, and there is an appropriate gap between the main shaft bearing and the base. Therefore, displacement of the head stock (spindle head) in the left-right direction does not cause the center of the spindle to move with respect to a certain reference point R (FIG. 2) set in the left-right direction.

Therefore, the center of the spindle is not affected by thermal displacement of the headstock (spindle head).

Further, according to the present invention, the center of the spindle is lowered below the mounting surface according to the difference in thermal displacement between the headstock (spindle head) and the base, so that the downward displacement of the headstock (spindle head) and the base mounting surface The upward displacement of is canceled out, and the vertical movement of the center of the spindle is greatly reduced.

Furthermore, according to the present invention, since a heat insulating material is provided between the headstock (spindle head) and the base that supports it, thermal displacement of the base is small and the distance between the mounting surface and the center of the spindle is also reduced. It can be made smaller.

Therefore, there is less need for a recess in the center of the base into which the headstock bearing part enters, allowing the base to maintain high rigidity.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of a conventional headstock. FIG. 2 is a cross-sectional view of one embodiment of the present invention. FIG. 3 is a plan view of one embodiment of the present invention. FIG. 4 is a thermal displacement curve showing the experimental results of one embodiment of the present invention. FIG. 5 is a cross section showing another embodiment of the present invention. FIG. 6 is a cross section showing another embodiment of the present invention. In the figure, 8...Main spindle (headstock),
9a, 9b... Jaw section, 11, 12...
Heat insulating material, 14...Support (base).

Claims (1)

[Claims] 1. A support provided on the reference fixing top surface, having mounting surfaces at the left and right upper ends, and having a concave portion in the center in a symmetrical shape, a first heat insulating member provided on the left and right mounting surfaces of the support, and A spindle head provided on the heat insulating member via a jaw and having a lower convex surface facing the four central parts of the support body with a space therebetween, and a spindle head provided between the lower convex portion of the spindle head and the concave surface of the support body. It consists of a second heat insulating member and a main shaft that is rotatably provided around an intersection that is at the symmetrical center of the spindle head and below the mounting surface of the support body, and when the temperature of the spindle head increases, A headstock characterized in that an amount of thermal displacement caused by the center of the spindle with respect to the mounting surface and an amount of thermal displacement of the support body caused by a temperature rise of the support body cancel each other out with respect to a reference plane of the bottom surface of the support body.