JP2003083324A - Rotary support mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary support mechanism always stably operable by restraining a change in a preload to a temperature change. SOLUTION: This rotary support mechanism has a housing 16 and a support shaft 15 mutually relatively rotatable via a bearing 11, and is characterized in that the rotary side housing 16 is formed of a lightweight material (aluminum) having a large thermal expansion coefficient, a bearing presser 19 for applying the preload to the bearing 11 is fastened and fixed to the housing 16 via a fixing bolt 20, a spot facing 23 having the prescribed depth is formed in an inserting part of the fixing bolt 20 in the housing 16, a section part of the spot facing 23 of the fixing bolt 20 is held in a noncontact state threadedly unengaged with the housing 16, and the bearing presser 19 and the fixing bolt 20 are formed of the same material as a constitutive material of the bearing 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to an industrial robot and
Rotation support machine used for rotation mechanism such as manipulator
About construction. [0002] 2. Description of the Related Art This type of rotation support mechanism is a cross roller shaft.
It is configured using a rolling bearing such as a bearing. FIG. 5 shows a configuration using cross roller bearings.
The structure of the conventional rotation support mechanism is shown,
The roller bearing 1 has an inner ring 2 and an outer ring 3 as race rings.
A plurality of rolling elements between the inner ring 2 and the outer ring 3
Cylindrical roller 4 is interposed. And the outer ring 3 is axial
And a pair of divided wheels 3a and 3b divided into
You. A support as a bearing coupling member is provided on the inner periphery of the inner ring 2.
The shaft 5 is fitted, and a bearing coupling member is provided on the outer periphery of the outer ring 3.
Of the two bearing coupling members
That is, the support shaft 5 and the housing 6 are
It rotates relative to each other via the receiver 1
You. In the example of FIG. 5, the support shaft 5 is fixed and the housing 6 is
It rotates integrally with the wheel 3. [0005] At the upper end of the support shaft 5, a bearing retainer 7 for the inner ring is provided.
The bearing retainer 7 is provided with a fixing bolt screwed into the support shaft 5.
The bearing retainer is fastened and fixed to the support shaft 5 by a bolt 8.
7, the inner race 2 is pressed in the axial direction, and the inner race 2 is supported by the pressure.
It is fixed to the shaft 5. A preloading mechanism is provided below the housing 6.
A bearing retainer 9 for the outer ring is provided.
The housing 6 is fixed by a fixing bolt 10 screwed into the housing 6.
The outer ring 3 is fixed to the ring 6
And a preload is applied to the bearing 1. [0007] SUMMARY OF THE INVENTION Such a rotary support machine
In the construction, the temperature rises during operation and each component
Expands. The material of the bearing 1 and the fixing bolt 10 is generally iron
If it is a steel material but the housing 6 is a rotating member
In this case, aluminum is used as the material of the housing 6 to reduce the weight.
Minium materials are often used. In this case, the aluminum material is replaced by a steel material.
The thermal expansion coefficient is larger than that of the
There is a difference in the amount of thermal expansion at a partial position.
The preload applied to the bearing 1 fluctuates. That is, the bearing retainer 9 for the outer ring and the housing
Position of the horizontal middle point at the point where
A, the position of the center axis of the fixing bolt 10 is B, and the bearing retainer 9 is
Horizontal midpoint at the point where the bearing 1 contacts the outer ring 3
Of the bearing 1 at each of these positions A, B and C.
Considering the amount of thermal expansion in the axial direction of the housing 6,
Is aluminum material, bearing 1 and bearing retainer 9 are steel
If it is a material, the thermal expansion amount Δ at the point A₁And point B
Thermal expansion Δ at position₂Is almost the same as
Thermal expansion Δ₃Is smaller than that (Δ₁≒ Δ₂>
Δ₃). As a result, the preload (bearing point C)
(In this case, decrease).
U. When the preload changes, the starting torque of the bearing 1 changes.
And the operation becomes unstable. That is, when the preload fluctuates, the rotation supporting machine
The rotational friction torque of the structure changes, and
In particular, multiple rotation support mechanisms are coaxially arranged.
In this condition, when the temperature changes, each other's rotational friction torque
Changes can affect each other,
It becomes unstable. Further, even when the temperature does not change much,
When a cross roller bearing is used as a bearing,
It is said that the fluctuation of the rotation torque of the mechanism tends to increase
There's a problem. This is because the cross roller bearing has high rigidity and
It is suitable for use in a rotary support mechanism because it is compact.
However, since the absolute value of the rotational torque is large,
Has a large effect on the value of the rotational torque
That's why. The present invention has been made in view of such points.
The purpose is always stable and desired
To provide a rotation support mechanism that can obtain preload
is there. [0014] According to the present invention, there is provided a rotary support mechanism according to the present invention.
In this case, the race and the array arranged along the race
Rolling bearings with a number of rolling elements, and
Two bearing coupling members rotatable relative to each other,
Material of the rolling bearing of the two bearing coupling members
Is one of the bearings made of materials with different coefficients of thermal expansion.
With preload for the rolling bearing attached to the joint member
And the preload applying mechanism is provided with the rolling shaft
The bearing has a bearing presser that presses the bearing ring in the axial direction.
The receiving retainer is a fixed bolt screwed into the one bearing coupling member.
The one bearing
The connecting member has a predetermined depth at the insertion portion of the fixing bolt.
A notch is formed, and the fixing bolt is located in a section of the notch.
In the non-contact state that does not screw with the one bearing coupling member
Is held, and the fixing bolt is attached to the one bearing coupling member.
It must be made of a material with a different coefficient of thermal expansion from that of the constituent materials.
It is characterized by. [0015] DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to FIGS. FIG. 1 shows a first embodiment.
Embodiment uses a cross roller bearing as a rolling bearing
It is an example of a rotating support mechanism. Cross roller bearing 11 is a rail
An inner ring 12 and an outer ring 13 as road wheels are provided.
A cylindrical cylinder as a plurality of rolling elements is provided between the ring 12 and the outer ring 13.
Filter 14 is interposed. The outer ring 13 has a pair of components separated in its axial direction.
Splitting wheels 13a and 13b are provided.
Are alternately rotated by approximately 90 ° in the axial direction.
And arranged in a ring arrangement (not shown).
At a predetermined interval. The cross roller bearing 11 is provided on the cylindrical roller.
Radial load and thrust load by 14 cross arrangements
Structure capable of effectively responding to heavy composite loads
It has become. On the inner periphery of the inner ring 12, a bearing coupling member
A cylindrical support shaft 15 is fitted, and a bearing
An annular housing 16 as a connecting member is fitted
I have. In this embodiment, the housing 16
Is a member that rotates integrally with the outer ring 13.
6 is made of aluminum material for its light weight
I have. At the upper end of the support shaft 15, a bearing retainer 1 for the inner ring is provided.
7, and the bearing presser 17 is screwed into the support shaft 15.
Is fixed to the support shaft 15 by the fixing bolt 18,
The inner ring 12 is pressed in the axial direction by the bearing retainer 17,
The inner ring 12 is fixed to the support shaft 15 by pressure. On the lower side of the housing 16, a preload applying mechanism is provided.
As a result, a bearing retainer 19 for the outer ring is provided.
9 is provided by a fixing bolt 20 screwed into the housing 16.
It is fastened and fixed to the housing 16. The fixing bolt 20 extends along the axial direction of the bearing 11.
Screwed into the housing 16 and tightened with the fixing bolt 20.
The outer ring 13 is pressed in the axial direction by the
And a preload is applied. A fixing bolt 20 is inserted into the housing 16.
A notch, for example, a spot facing 23, is formed for
The fixing bolt 20 is screwed into the counterbore 23 in the depth direction.
Screw holes 24 are formed. Counterbore 23
The inner diameter is larger than the outer diameter of the fixing bolt 20 and the fixing bolt 2
No. 0 has this counterbore 23 loosely inserted and screwed into the screw hole 24
I have. That is, the fixing bolt 20 is
In the section 3, it is in a non-contact state that does not screw with the housing 16.
Only the part that is retained and screwed into the screw hole 24 is the housing 1
6. The lower end surface of the outer ring 13 of the bearing 11 is
The projection 16 projects slightly below the lower end surface of the projection 16.
The bearing retainer 19 contacts the lower end surface of the housing 16.
The first contact portion 19a to be touched and the lower end surface of the outer ring 13
And the second contact portion 19b
Fixing bolt at a position between the first contact portion 19a and the second contact portion 19b.
20 has been inserted. The housing 16 is made of aluminum to reduce its weight.
The bearing 11 is made of a minium material.
The material of the presser foot 19 and the fixing bolt 20 is based on their strength.
It is formed of a steel material. Therefore, when the temperature rises, the bearing 1
When considering the extension in the axial direction of the housing 1, the housing 1
6 has no counterbore 23 and the housing 1 of the fixing bolt 20
6 is screwed into the housing 16
If so, as described above, the first
Thermal expansion at the point A at the horizontal intermediate point of the contact portion 19a
Tension Δ₁And at the position of point B on the center axis of the fixing bolt 20
Thermal expansion Δ₂In the horizontal direction of the second contact portion 19b
Thermal expansion Δ at point C at the intermediate point₃Is related to Δ₁≒
Δ₂> Δ₃It becomes. On the other hand, in the present embodiment, the how
Counterbore at the insertion part of the fixing bolt 20 to the jing 16
23 are formed, and the depth of the counterbore 23
The amount of thermal expansion of the fixing bolt 20 at the part
Thermal expansion at point B
Quantity Δ₂Is smaller than the above case, Δ₁> Δ₂> Δ ₃
It becomes the relationship. According to this relationship, the bearing retainer 19 is
The decrease in bending stress between B and C becomes smaller,
The fluctuation (decrease) of the preload on the bearing 11
Can be To explain further, Distance L between AB₁ Distance L between BC₂ The depth of the spotbore 23 is H₁ Distance between the lower end surface of housing 16 and the upper end surface of bearing 11
Release H₂ Projection of first contact portion 19a with respect to second contact portion 19b
Height H₃ Thermal expansion coefficient ρ of housing 16 (aluminum material)₁ Thermal expansion coefficient ρ of bearing 11 (steel material)₂ Thermal expansion coefficient ρ of bearing retainer 19 (steel material)₃ Thermal expansion coefficient ρ of fixing bolt 20 (steel material)₄ Temperature change amount t And when Thermal expansion Δ at point A₁Is Δ₁= H₂・ Ρ₁・ T + H₃・ Ρ₃・ T Thermal expansion Δ at point B₂Is Δ₂= (H₂-H₁) ・ Ρ₁・ T + (H₁+ H₃) ・ Ρ
₄・ T Thermal expansion Δ at point C₃Is Δ₃= (H₂+ H₃) ・ Ρ₂・ T It becomes. Here, the force for pressing the outer ring 13 of the bearing 11
In order to keep the (preload) constant, the fixing
The amount of thermal expansion on both sides of the bolt 20 is balanced
It just needs to be kept in shape, L₁: L₂= (Δ₁−Δ₂): (Δ₂−Δ₃) It becomes. Therefore, this L₁: L₂= (Δ₁−Δ
₂): (Δ₂−Δ₃Counterbore 2 so as to satisfy condition
3 depth H₁, The bearing 11 with respect to a change in temperature
Preload fluctuations can be almost eliminated, so
New That is, L₁, L₂, H₂, H₃,
ρ₁, Ρ₂, Ρ₃, Ρ₄Is a known value and H₁Only unknown
Is the value of H₁= ｛L₁・ H₂・ Ρ₁-L₁・ (H₂+ H₃) ・ Ρ
₂-L₂・ H₃・ Ρ ₃+ (L₁+ L₂) ・ H₃・ Ρ₄｝
/ ｛(L₁+ L₂) ・ (Ρ₁−ρ₄)｝ And H₁If this is satisfied, the bearing retainer 19
The force (preload) pressing 13 does not change even if the temperature changes.
Will be. For example,     ρ₁= Ρ_a     ρ₂= Ρ₃= Ρ₄= Ρ     H₃= 0     H₂= H     L₁= L₂= L If     H₁= (L ・ H ・ ρ_a−L · H · ρ) / ｛(2 · L) · (ρ_a−ρ)｝        = L ・ H ・ (ρ_a−ρ) / ｛(2 · L) · (ρ_a−ρ)｝        = H / 2 It becomes. On the other hand, in the present embodiment, the rolling bearing
The cross roller bearing 11 is used as the first embodiment. This cross
The roller bearing 11 has a radial (radial) and
Can support both the load in the strike direction (axial direction) and rolling
Since the cylindrical roller 14 is used as the body, the rigidity is high,
There is an advantage that it is more compact. However, due to the manufacturing process, the split ring 1 of the outer ring 13
The axis of the outer peripheral surface of 3a, 13b,
The center of the raceways 13a 'and 13b' inside 13b is
Sometimes it is difficult to make a perfect match. For this reason, the outside of the two split wheels 13a, 13b
When both the peripheral surfaces are brought into close contact with the inner peripheral surface of the housing 16,
The track surfaces 13a ', 13b' of the split wheels 13a, 13b are
It is easy to get out of alignment and this is the starting torque
It causes variation. Therefore, in this embodiment, a pair of components
Only the outer peripheral surface of one of the split wheels 13a, 13b
To the inner peripheral surface of the housing 16 for restraint.
The outer peripheral surface of the split wheel 13b is in close contact with the inner peripheral surface of the housing 16.
A small gap S is provided between the two
And thus the raceway surface 13a 'of one of the split wheels 13a
And the axis of the raceway surface 13b 'of the other split wheel 13b
Are matched. The outer peripheral surface of one split wheel 13a is
The rotation of the housing 16 is brought into close contact with the outer peripheral surface of the housing 16.
A reference plane for matching the center to the rotation center of the bearing 11
However, the accuracy required for that purpose is
Between the raceway surfaces 13a 'and 13b' of the split wheels 13a and 13b.
It is looser than the accuracy required for axis alignment. The present invention is not limited to the above-described embodiment.
Fixing of the housing 16 as shown in the second embodiment
A counterbore 23 is formed in the bolt insertion portion, and
In the support shaft 15 fitted to the inner ring 12 of the ball bearing 11
Also, a counterbore 23 is formed in the fixing bolt insertion portion,
Fixing bolt 18 screwed into the screw hole 24 through the screw 23
The bearing retainer 17 for the inner ring is fastened and fixed to the support shaft 15 with
The inner ring 12 of the bearing 11 is pressed and fixed by the bearing retainer 17.
Such a configuration is also possible. In such a structure
According to this, the force of pressing the inner ring 12 when the temperature changes
Fluctuations can also be suppressed. FIG. 3 shows a third embodiment.
As described above, a ball bearing such as a combination ball bearing 1 is used as a rolling bearing.
1a may be used. This ball bearing 1
Reference numeral 1a denotes an inner ring 12 and an outer ring 13 as race rings, and rolling
It is composed of a plurality of balls 14a as a body. The housing fitted on the outer periphery of the outer ring 13
The bearing retainer 19 is fastened to the bracket 16 via the fixing bolt 20.
The outer ring 1 of the ball bearing 11a is
3 is pressed in the axial direction, and a preload is applied. In each of the above embodiments, the housing 1
A counterbore 23 is formed as a notch in
Screw a predetermined section of the fixing bolt 20 with the housing 16
Not to be kept in a non-contact state, but the counterbore
As shown in FIG. 4 as a fourth embodiment instead of 23,
A recessed portion 23a which is recessed in a stepped manner as a cutout portion in the housing 16.
Is formed, and a predetermined fixing bolt 20 is formed by the concave portion 23a.
Section is kept in a non-contact state that does not screw with the housing 16
You may make it. A conventional product having the structure shown in FIG.
Manufacture a plurality of the products of the present invention having the configuration shown
(25 ° C) and rotation start under high temperature (60 ° C)
When the torque was measured, the conventional product under each temperature condition
Start-up torque varies greatly between
In some cases, the change in starting torque between high and high temperatures is small.
However, some of them are large, and it is possible to obtain the desired torque value.
It was difficult. In the product of the present invention, under each temperature condition
The variation in the starting torque of each of the
Lux value and can be started between room temperature and high temperature.
The change in dynamic torque could be suppressed. In each of the above embodiments, the rolling
A bearing coupling member (c) in which the outer ring 13 of the bearing is fitted around its outer periphery
This is an example of the case of rotating together with the housing 16).
One of the bearing coupling members (housing
16) and the other bearing fitted to the inner ring 12
The member (support shaft 15) may be rotated. In this case, the support, which is the rotating member,
The shaft 15 is made of, for example, aluminum material for weight reduction,
The housing 16 which is a fixed member is made of the same steel as the bearing 11.
Materials. And a support shaft 15 made of aluminum material
In consideration of the thermal expansion of the shaft, a counterbore or a step
A notch formed of a portion or the like is formed. A cross roller bearing is used as a rolling bearing.
In the case where 11 is used, in FIGS. 1, 2 and 3,
Although the ring 13 has a divided structure, the inner ring 12 has a divided structure.
Then, the inner ring 12 having the divided structure is pressed by the preload applying mechanism.
Such a configuration is also possible. In this case, any one of the split wheels of the inner ring 12 is used.
Only the inner surface of one side is tightly attached to the outer surface of the spindle,
The non-constrained state reduces the variation of the starting torque
Can be More preferably, the outer ring is divided into two parts.
This is the same as the case where the structure is made. Further, an inner ring as a bearing ring of a rolling bearing
When the outer ring 12 and the outer ring 13 are configured as a single component,
Not limited to, for example, the inner ring 12 and a member (support shaft) connected to the inner ring 12
When the material is the same, a part of the member (support shaft)
12 or to be connected to the outer ring 13
When the member (housing 16) is made of the same material,
A part of the material (housing 16) forms the outer race 13
It may be. [0051] According to the present invention as described above,
Two bearings rotatable relative to each other via ball bearings
Thermal expansion different from the material of the rolling bearing of the coupling member
One of the bearing coupling members made of
A notch such as a recess is formed, and the fixing bolt is inserted through this notch.
Screw into the one bearing coupling member, and
By fastening the bearing retainer for applying preload to the bearing coupling member
The bearing is fixed, so the bearing
It is possible to always operate stably by suppressing pressure fluctuation
Become.

[Brief description of the drawings] FIG. 1 is a sectional view showing a first embodiment of the present invention. FIG. 2 is a sectional view showing a second embodiment of the present invention. FIG. 3 is a sectional view showing a third embodiment of the present invention. FIG. 4 is a sectional view showing a fourth embodiment of the present invention. FIG. 5 is a sectional view showing a conventional technique. [Explanation of symbols] 11 Cross roller bearing (rolling bearing) 11a Ball bearings (rolling bearings) 12 ... Inner ring (track ring) 13 ... Outer ring (track ring) 14: Cylindrical roller (rolling element) 14a ... ball (rolling element) 15. Support shaft (bearing coupling member) 16 Housing (bearing coupling member) 19 ... Bearing retainer 20 ... fixing bolt 23 ... counterbore (notch) 23a recess (notch) 24 ... Screw hole

Claims (1)

Claims: 1. A rolling bearing comprising a bearing ring and a plurality of rolling elements arranged along the bearing ring, and two bearing coupling members rotatable relative to each other via the rolling bearing. And a preload applying mechanism for the rolling bearing attached to one of the bearing coupling members formed of a material having a different coefficient of thermal expansion from the constituent material of the rolling bearing of the two bearing coupling members, The preload applying mechanism has a bearing retainer that presses the bearing ring of the rolling bearing in the axial direction, and the bearing retainer is fastened to the bearing coupling member by a fixing bolt screwed into the one bearing coupling member. A notch of a predetermined depth is formed in one of the bearing coupling members at the insertion portion of the fixing bolt,
The fixing bolt is held in a non-contact state in which it is not screwed with the one bearing coupling member in the section of the notch, and the fixing bolt is formed of a material having a different thermal expansion coefficient from a material of the one bearing coupling member. A rotation supporting mechanism.