JP2591620Y2 - Preload switching spindle unit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preload switching type spindle unit used for a spindle of a machine tool or the like.

[0002]

2. Description of the Related Art In a spindle of a machine tool, when the main spindle performs heavy cutting at a low speed, the preload of the bearing is increased to increase the rigidity of the main spindle. Conversely, when the main spindle is rotated at a high speed, the preload of the bearing is decreased. A function that reduces the rigidity and suppresses the heat generation of the bearing is required.

Conventionally, as a spindle unit in which the preload applied to a bearing is varied according to the rotation speed of the main shaft, there is a spindle unit proposed by the present applicant in Japanese Utility Model Application No. 2-82887.

[0004] As shown in FIG. 8, the proposed unit includes a bearing 43 for supporting a main shaft 42 inside an outer cylinder 41.
A bearing box 45 and an intermediate ring 46 that press the shaft 44 in the axial direction are movably provided, and an adjusting member 47 that limits the amount of movement of the bearing box 45 and the intermediate ring 46 is attached to the outer cylinder 41. , And pressure chambers 48 and 49 facing the end face of the bearing box 45 are provided.

Further, gaps δ ₁ and δ ₂ having different sizes are provided between the adjusting member 47 and the bearing box 45 and between the adjusting member 47 and the intermediate ring 46, and high-pressure oil or the like is provided in each of the pressure chambers 48 and 49. The preload applied to each bearing is changed by introducing and discharging the working fluid described above and moving the bearing box 45 in the axial direction.

[0006]

In the unit proposed above, the adjusting member 47 for adjusting the amount of movement of the bearing housing includes a movement amount limiting ring 50 which engages with the inner diameter side of the bearing housing 45 and the intermediate ring 46, and an outer ring. The positioning flange 51, which is in contact with the end surface of the cylinder 41, is integrally fixed by welding or the like. In such a structure in which the positioning flange 51 is fixed by welding or the like, the members 50, 51 joined by welding heat or the like are used. Deformation is likely to occur, and it is difficult to maintain the accuracy of the adjustment member 47.

Further, in a structure in which the limiting ring 50 having a plurality of steps 52 and 53 with which the bearing box 45 and the like are engaged and the positioning flange 51 are integrally connected, when the unit is assembled, the limiting ring 50 is attached to the intermediate ring 46. When the positioning flange 51 and the restriction ring 50 are
Need to be fixed together by welding or the like, which has a disadvantage in that the assembling property is poor.

On the other hand, as shown in FIG. 9 , a restricting ring, which is an adjusting member , is radially connected to a plurality of rings 54, 55.
And a structure in which they are fixed by tightening the nut 56 is also conceivable . However, the adjustment member is
As long as the rings 54 and 55 are divided in the same direction , not only the radial thickness of the divided rings 54 and 55 is reduced , but also the rings 54 and 55
5. The area of the overlapping radial division planes becomes smaller.
The same as the conventional split structure of the adjusting member shown in FIG.
In addition, the surface pressure applied to this radial split surface during operation is large
It becomes, the adjustment member 4 in limiting the amount of movement of the bearing housing 45
7 is difficult to obtain.

The present invention has been made in view of the above circumstances and aims to provide a variable preload spindle unit which can solve the above-mentioned problems and can easily assemble an adjusting member without reducing mechanical strength and shape accuracy. I have.

[0010]

In order to solve the above-mentioned problems, the present invention proposes that a main shaft is inserted into an outer cylinder through which the main shaft is inserted.
Bearing housing for pressing the bearing to be supported in the axial direction, and the bearing housing
An adjusting member for limiting the amount of movement of the outer cylinder and the bearing housing is provided.
A pressure chamber through which the working fluid is introduced and discharged,
By introducing fluid into the pressure chamber of
Pressurized preload switching type spindle unit
And the adjusting member reaches the inner diameter surface of the adjusting member.
Divided into two or more members having a radial dividing surface,
With an axial bolt that penetrates the
The preload switching spindle is formed by fixing the above members
It was a unit configuration.

[0011]

The preload switching type according to the present invention having the above-mentioned structure.
The spindle unit has a diameter that reaches the inner diameter surface of the adjustment member.
Divided into two or more members having a dividing surface in the radial direction.
Divided by an axial bolt passing through the dividing surface of
Since each member is fixedly formed, the radial thickness of each member is
The thickness increases, and the adjustment members are formed by fixing each member.
When it is formed, the area of the radial dividing surface that each member contacts
It will be good. Because of this, these radial splits during operation
The surface pressure on the surface is relatively small, and the rigidity of the adjustment member
Is improved.

Further, since the respective members to be divided are fixed by tightening them with bolts, the assembling of the adjusting member can be easily performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the main shaft 2 penetrates the inside of the outer cylinder 1, and both end portions of the main shaft 2 are arranged in parallel with their back faces facing each other. 6 rotatably supported.

The angular ball bearings 5 and 6 on one end side are
The inner ring is fixed to the outer diameter surface of the main shaft, and the outer ring is fixed to the inner surface of a bearing box 7 inserted into the outer cylinder 1, and the end surface of the bearing box 7 is connected to the bearing 5 through the spacer 8. It is in contact with the outer ring end face.

An intermediate ring 9 that can move in the axial direction is inserted beside the bearing box 7, and restricts the amount of movement of the bearing box 7 and the intermediate ring 9 between the intermediate ring 9 and the main shaft 2. The adjusting member 10 is incorporated.

The adjusting member 10 is provided on the inner end wall 1 of the outer cylinder 1.
a positioning flange 11 which comes into contact with a
And two moving amount limiting rings 12 and 13 inserted on the inner diameter side of the bearing box 7.

The two limiting rings 12 and 13 and the positioning flange 11 are respectively divided in the axial direction in the entire adjustment member 10, and the recesses 14 and 15 provided in the positioning flange 11 and the outer limiting ring 12 are provided. Then, the outer limiting ring 12 and the inner limiting ring 13 are fitted to each other, and the three members are combined in a state of being overlapped in the axial direction.

Also, a plurality of bolts 16 inserted from the positioning flange 11 are screwed into the screw holes 17 of the inner limit ring 13 through the limit ring 12. , 13 and the positioning flange 11 are integrally fixed.

Further, a first pressure chamber 18 is formed between the bearing housing 7 and the intermediate ring 9 in a state where the adjusting member 10 is assembled as shown in FIG. 2, and the intermediate ring 9 and the positioning flange 11 are formed.
A second pressure chamber 19 is formed between the pressure chambers 18, and passages 20, 21 inside the outer cylinder 1 are respectively formed in the pressure chambers 18, 19.
The hydraulic control device 22 is connected via the. The hydraulic control device 22 includes an electromagnetic control valve, a hydraulic pump, and the like, and is set so that hydraulic oil of a required pressure is introduced into and discharged from each of the pressure chambers 18 and 19 based on a signal from a sensor that detects the rotation speed of the main shaft 2. Have been.

The outer limiting ring 12 of the adjusting member 10 is provided with a step 23 for engaging with the intermediate ring 9, and the inner limiting ring 13 is engaged with the step 25 of the bearing housing 7. A stepped portion 24 is formed, and a predetermined gap 26 is provided between the end face of the bearing housing 7 and the outer limiting ring 12. Further, in the state of the initial preload incorporating the bearing (the state of FIG. 2), the gap δ ₂ between the step portion 24 of the inner limiting ring 13 and the step portion 25 of the bearing box 7 is changed to the step of the outer limiting ring 12. The clearance δ ₁ between the portion 23 and the end face of the intermediate ring 9 is set to be larger (δ ₁ <δ ₂ ).

The outer peripheral surface of the bearing housing 7 has a spiral groove 2
7 is formed, and the electromagnetic control valve 2 is
The hydraulic control device 22 is connected to the hydraulic control device 8 via the control unit 8. In this structure, when hydraulic pressure is applied to the spiral groove 27 by the hydraulic pressure control device 22, the bearing box 7 is reduced in diameter and a gap is formed between the bearing box 7 and the inner diameter surface of the outer cylinder 1, and the axial movement of the bearing box 7 is reduced. Easy to do.

The spiral groove 27 may be provided on the inner diameter side of the outer cylinder 1. The spiral groove 27 is not limited to the spiral groove 27, and may be formed in such a manner that a gap is formed between the bearing housing 7 and the outer cylinder 1 by hydraulic pressure. Should be fine.

The spindle unit of this embodiment has the above-mentioned structure, and the adjusting member 10 has a divided structure and is fixed by the bolts 16, so that the assembling work is facilitated and the heat generated by welding heat or the like is improved. Since the material is not deformed, a unit having good shape accuracy can be assembled.

Further, the adjusting member 10 is connected to the positioning flange 1.
Divided into three members: 1 and movement limit rings 12 and 13
However, each of these members reaches the inner diameter surface of the adjustment member.
Since the radially divided surface is provided, a large radial thickness of each member necessary for mounting the bolt can be secured. Therefore, the size of the bolt 16 can be increased, and each member can be firmly fixed. In addition, the positioning flag
Adjusting by fixing the flange 11 and the movement limit rings 12 and 13
When the members are formed, the members 11, 12, and 13 come into contact with each other.
Since the matching radial division surface is also large,
The surface pressure applied to the radial division surface becomes relatively small,
The rigidity of the adjusting member is improved.

Next, a method of switching the preload amount using the spindle unit will be described.

First, in order to apply a large preload to the bearing at a low speed rotation, in FIG. 2, hydraulic oil is supplied to the first pressure chamber 18 while the oil pressure is released from the second pressure chamber 19 to apply pressure. Thereby, as shown in FIG.
Moves to the left, and the bearing box 7 moves to a position where it comes into contact with the step portion 24 of the outer limiting ring 13. Therefore, a preload P ₁₀ corresponding to the clearance δ ₂ is applied to the bearings 5 and 6, A preload state is established (see FIG. 5).

From this state, when the rotation of the spindle 2 increases,
Due to the centrifugal force, thermal expansion of the main shaft, and the like, the preload of the bearing gradually increases as shown in FIG. When the preload reaches the allowable maximum preload (Pmax) (N ₂ ), the hydraulic pressure is released from the first pressure chamber 18, and hydraulic oil is introduced into the second pressure chamber 19. As a result, as shown in FIG.
The intermediate ring 9 moves until it comes into contact with the step portion 23 by the pressure of the above, and the bearing housing 7 is returned to the position where it comes into contact with the intermediate ring 9, and the bearings 4 and 5 are applied with a preload P of an amount corresponding to the clearance δ _{1. 20} is added. Therefore, as shown in FIG. 5 (b), the preload applied to the bearing is reduced, it switched to medium preload P _20.

Further, the number of revolutions of the main shaft 2 increases, and FIG.
As shown in (c), the preload is again changed to the allowable maximum preload Pmax.
(At time N ₂ ), the first and second pressure chambers 18,
Drain hydraulic oil from 19. As a result, the bearing housing 7 and the intermediate ring 9 move to the left, and return to the initial state shown in FIG.
Preload P ₃₀ corresponding to the amount of initial clearance during assembly the bearing 4, 5 is applied. Therefore, preload applied to the bearing as shown in FIG. 5 (d) is further reduced, switched to a light preload P _30.

When the preload is switched in each of the above stages, hydraulic oil is supplied to the spiral groove 27 of the bearing box 7 to reduce the diameter of the bearing box 7. This facilitates movement of the bearing housing 7 and enables smooth preload switching.

FIG. 6 shows another embodiment. In this example, the intermediate ring is omitted from the structure of the above embodiment,
1 for engaging the movement limiting ring of the adjusting member 10 with the bearing housing 7
Each ring 30 is formed. In this structure, a preload amount corresponding to a clearance δ ₁ between the restriction ring 30 and the bearing housing 7 and an initial clearance of the bearing can be set, and preload switching can be performed in two stages.

On the other hand, in the example shown in FIG.
Two intermediate rings 31 and 32 are provided between the positioning ring 11 and the positioning flange 11 of the adjustment member 10, and the intermediate rings 31 and 32 are provided.
Two pressure chambers 33, 34, 35 are provided on both sides of 2. Also, three step portions 3 are provided on the movement restriction rings 12 and 13.
6, 37, 38 are formed, and the respective steps 36, 37, 38 are formed.
The gaps δ ₁ , δ ₂ , δ ₂ are respectively provided between the bearing and the intermediate rings 12, 13 and the bearing housing 7. In this structure,
A preload corresponding to each of the gaps δ ₁ , δ ₂ , δ ₃ and the initial gap can be set for the bearing, and four-stage preload switching can be performed.

In the above, if the number of intermediate rings and the number of steps of the adjusting member are increased, the number of preload switchings can be further increased.

In the above embodiment, high-pressure oil is introduced into the spiral groove of the pressure chamber or the bearing box. Alternatively, compressed air or other working fluid may be supplied.

[0034]

As described above, according to the present invention, the adjusting member has a divided structure, and each of the divided members is fixed by bolts. Therefore, assembling can be easily performed as compared with a structure in which the adjusting members are integrally fixed by welding or the like. There is no deformation of the material due to welding heat or the like.

The adjusting member reaches the inner diameter surface of the adjusting member.
Divided into two or more members having a radial division surface
Then, it is only divided in the radial direction shown in FIG. 8 and FIG.
Adjustment member with a split structure without a radial split surface reaching the radial surface
The radial thickness of each divided member is larger than
Therefore, the rigidity of the adjustment member is improved. In addition, each divided member
When the preload is applied,
The surface pressure applied to these radial division surfaces is relatively small.
And can withstand greater preload.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment.

FIG. 2 is an enlarged sectional view showing a main part of the above.

FIG. 3 is a sectional view showing an operation state of the above.

FIG. 4 is a sectional view showing an operation state of the above.

FIG. 5 is a graph showing a process of switching the preload according to the first embodiment;

FIG. 6 is a sectional view showing another embodiment.

FIG. 7 is a sectional view showing another embodiment.

FIG. 8 is a sectional view showing a conventional example.

FIG. 9 is a sectional view showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Main shaft 7 Bearing box 9 Intermediate ring 10 Adjusting member 11 Positioning flange 12, 13 Movement limit ring 16 Bolt 18 First pressure chamber 19 Second pressure chamber 22 Hydraulic control device 30 Movement limit ring 31, 32 Intermediate ring 33, 34, 35 Pressure chamber

Claims (1)

(57) [Scope of request for utility model registration] A bearing box for pressing a bearing supporting a main shaft in an axial direction and an adjusting member for limiting a moving amount of the bearing box are provided inside an outer cylinder through which the main shaft is inserted. A pressure chamber through which a working fluid is introduced and discharged, and a preload switching spindle unit that presses the bearing box in the axial direction by introducing a fluid into the pressure chamber ; Radial direction reaching the inner diameter surface of this adjustment member
Divided into two or more members having a dividing surface of
The above divided by the axial bolt penetrating the dividing surface
A preload switching spindle unit wherein each member is fixedly formed .