JP2004142022A - Spindle bearing lubrication structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle bearing lubrication structure wherein effectively utilizing the motor output in machining a work. <P>SOLUTION: A spindle 20 has a tool-fitting screw hole 20g in the front end thereof, and is supported by a casing 10 via rolling bearings 22 and 28. A rotor 24 to constitute a motor is fixed to the spindle 20, and a stator 14 is disposed therearound. Nozzles 33 and 35 to feed oil mist are disposed on parts corresponding to the bearings 22 and 28. These nozzles 33 and 35 are provided to spray oil mist from the upstream side toward the downstream side in a rotational direction of the spindle 20 with respect to the bearings 22 and 28. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing lubrication structure for a main shaft such as a processing device in which the main shaft is directly driven by a motor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, some processing devices such as lathes and drilling machines have, for example, a rotor that constitutes a spindle drive motor fixed directly to a spindle, and a stator disposed around the rotor to drive the spindle at high speed. There is.
[0003]
In this type of processing apparatus, a main shaft is supported on the casing of the apparatus via rolling bearings on both sides of the rotor portion, and a stator is fixed to the casing so as to surround the rotor from outside. The casing is provided with nozzles corresponding to the front and rear bearings supporting the main shaft, and oil mist (lubricating oil) is sprayed from the nozzles to each bearing, thereby preventing bearing seizure due to high-speed driving. It is configured as follows. The nozzle is provided in the vicinity of the bearing, and is generally provided so as to blow oil mist to the bearing from a direction orthogonal to the rotation direction of the main shaft (a direction parallel to the main shaft).
[0004]
[Problems to be solved by the invention]
In such a processing apparatus, higher-speed driving is required, and in recent years, driving at, for example, 100,000 to 180,000 rotations per minute has been required.
[0005]
However, if the main shaft is driven at higher speed, it is difficult to increase the bearing span due to the restriction of the resonance frequency of the main shaft, and it is necessary to reduce the effect of centrifugal force. Therefore, the output (torque) of the hard motor tends to decrease. Therefore, it is necessary to use the motor output more effectively for processing the workpiece, and it is necessary to review the lubrication structure of the main shaft bearing from this viewpoint.
[0006]
The present invention has been made in view of the above problems, and has as its object to provide a bearing lubrication structure for a main shaft that can more effectively utilize a motor output for processing a work.
[0007]
[Means for Solving the Problems]
The present invention relates to a conventional lubricating structure, that is, a structure in which lubricating oil is sprayed on a bearing from a direction orthogonal to a rotating direction of a main shaft (a direction parallel to the main shaft). Focusing on the fact that the relative speed is deviated in the opposite direction of rotation, the rotational resistance increases and the loss of motor output (torque) increases, and from this viewpoint, the lubrication structure for the main shaft bearing is reviewed.
[0008]
That is, a lubricating structure of the bearing of a processing device having a tool mounting portion at a front end, rotatably supported by a casing via a bearing, and rotating the main shaft by a motor. A nozzle for supplying lubricating oil is provided, and the nozzle is provided so as to spray the lubricating oil from the upstream side to the downstream side in the rotational driving direction of the main shaft with respect to the bearing.
[0009]
According to such a lubricating structure, since the spraying pressure of the lubricating oil acts on the bearing from the upstream side to the downstream side in the rotational driving direction of the main shaft, even if the rotational speed of the main shaft increases, the lubricating oil sprayed on the bearing is increased. Is less likely to be deviated in the reverse direction of the rotation direction, and is less likely to cause rotational resistance of the main shaft. Further, the spray pressure of the lubricating oil also acts as a rotation assisting force of the main shaft. Therefore, the mechanical loss of the motor output due to the spraying of the lubricating oil can be reduced as compared with the conventional structure.
[0010]
In this bearing lubrication structure, a specific inclination angle of the nozzle can be appropriately selected. However, as described in detail in the embodiment of the present invention, in order to more effectively exert the above-described operation and effect, 10 It is preferable that the lubricating oil is supplied in a direction inclined in the range of 30 ° to 30 °.
[0011]
When the processing device has a cover member that is attached to the casing and covers the bearing from the direction of the main shaft, the cover member has a nozzle forming hole that opens toward the bearing, and a nozzle forming hole that opens toward the bearing. It is preferable to provide a supply passage for supplying lubricating oil to the hole.
[0012]
According to this configuration, the nozzle as described above can be provided near the bearing by using the existing cover member, and the configuration is rational.
[0013]
Further, in this structure, it is preferable to provide a plurality of nozzles around the main shaft as the nozzles.
[0014]
According to this structure, since the blowing pressure of the lubricating oil acts from a plurality of locations, the rotation assisting effect of the main shaft can be enhanced, and the loss of the motor output can be further reduced.
[0015]
In addition, such a bearing lubrication structure particularly has a so-called direct drive structure in which a rotor constituting the motor is fixed to an intermediate portion of a main shaft, and both front and rear sides of the rotor fixed portion are rotatably supported by the bearings. It is useful in processing equipment having In other words, such a main shaft structure is often used in high-speed rotation type devices, but in this high-speed rotation type device, it is difficult to increase the bearing span due to the restriction of the resonance frequency of the main shaft, and the effect of centrifugal force is reduced. Therefore, the size of the rotor fixed to the main shaft has to be reduced, and the output (torque) of the motor tends to decrease. Therefore, in this kind of spindle structure, it is particularly required that the motor output can be effectively used for machining the work.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of the present invention will be described with reference to FIGS. Although FIG. 1 shows a spindle head in an internal grinding machine, the present invention is not limited to this, and can be applied to various processing apparatuses having a spindle.
[0017]
The spindle head shown in FIG. 1 includes a casing 10, in which a spindle 20 extending in the front-rear direction (the left-right direction in FIG. 1) is rotatably supported.
[0018]
The main shaft 20 shown in the figure has a front bearing fixing portion 20a, a front bearing positioning portion 20b, a rotor positioning portion 20c, a rotor fixing portion 20d, and a sleeve mounting portion 20e in order from the front end side. The front bearing fixing portion 20a is provided with a tool mounting screw hole 20g that opens forward, and a suitable rear end of the tool is screwed into the tool mounting screw hole 20g so that the tool is fixed to the front end of the spindle. It is supposed to be. Note that the outer diameter of the main shaft 20 is the largest at the front bearing positioning portion 20b, followed by the front bearing fixing portion 20a, the rotor positioning portion 20c, the rotor fixing portion 20d, and the sleeve mounting portion 20e.
[0019]
The inner ring of a front bearing (rolling bearing in the illustrated example) 22 is fixed to the front bearing fixing portion 20a at a position where the front bearing contacts the front bearing positioning portion 20b from the front, and the rotor fixing portion 20d is fixed to the rotor positioning portion 20c. The rotor 24 is fixed in a state of hitting from behind.
[0020]
Further, a sleeve 26 is fixed to the sleeve mounting portion 20e in a state where the sleeve 26 comes into contact with the rear end of the rotor fixing portion 20d from behind. The outer diameter of the front portion 26a of the sleeve 26 is larger than the outer diameter of the rear portion 26b, and has a shape in which a step is formed at the boundary between the front and rear portions 26a and 26b. The inner ring of the rear bearing (rolling bearing in the illustrated example) 28 is fixed to the rear portion 26b in a state where the inner ring of the rear bearing (rolling bearing in the illustrated example) contacts the front portion 26a from behind.
[0021]
In addition, besides the illustrated rolling bearing, for example, a sliding bearing can be applied to the front bearing 22 and the rear bearing 28.
[0022]
On the other hand, on the casing 10 side, the outer ring of the front bearing 22 is fixed to the inner peripheral surface of the front wall while the front end of the main shaft 20 penetrates the front wall (the left side wall in FIG. 1). A cover member 30 is fixed to the front wall of the casing 10 so as to cover the bearing 22 with the main shaft 20 penetrating therethrough.
[0023]
In the casing 10, a bearing holding sleeve 16 is held via a ball bearing 15 so as to be able to move back and forth, and the bearing holding sleeve 16 is urged forward by the elastic force of a compression coil spring 18. An outer ring of the rear bearing 28 is fixed to an inner peripheral surface of the rear bearing 16. Thus, the main shaft 20 is rotatably supported by the casing 10 via the front and rear bearings 22 and 28. Further, at a position surrounding the rotor 24, a stator 14 which constitutes a spindle drive motor together with the rotor 24 is fixed, and by energization of the stator 14, the spindle 20 and a tool mounted thereon are driven to rotate integrally at a high speed. It has become.
[0024]
An oil mist (lubricating oil) supply port 11 is provided at the rear end of the casing 10, and an oil mist supply passage 12 extending from the oil mist supply port 11 is formed in the casing 10. The oil mist is supplied to the right place.
[0025]
In particular, the front cover member 30 fixed to the front wall of the casing 10 and the rear cover member 32 fixed to the rear wall (the right side wall in FIG. 1) of the casing 10 and supporting the compression coil spring 18 from the rear side. The nozzle of the front cover member 30 supplies oil mist from the front side (the left side in FIG. 1) to the front bearing 22 from the nozzle of the front cover member 30, while the nozzle of the rear cover member 32 The oil mist is supplied to the rear bearing 28 from the rear side.
[0026]
More specifically, as shown in FIG. 2, the front cover member 30 has a ring-shaped concave portion 39 centered on the main shaft 20 and an outer side from the concave portion 39 (see FIG. A recess 31 extending upward is formed in the casing 10 and the cover member 30 is fixed to the casing 10 as described above. A ring-shaped supply passage is formed, and this ring-shaped supply passage communicates with the oil mist supply passage 12 of the casing 10 via the recess 31. Further, inside the front cover member 30, a supply path 34 a that opens inside the ring-shaped recess 39 and extends from the outside in the radial direction to the inside, and from the front end of the supply path 34 a to the rear end side of the main shaft 20. A nozzle forming hole 34b extending toward the front bearing 22 and extending toward the front bearing 22 is formed. As a result, when oil mist is introduced into the casing 10 from the oil mist supply port 11, the oil mist is supplied to the oil mist supply passage 12, the concave portion 31, the ring-shaped supply passage (ring-shaped concave portion 39), the supply passage 34a, and the nozzle formation. The fuel is injected into the front bearing 22 from the front side through the hole 34b.
[0027]
As shown in FIG. 1, the rear cover member 32 has a supply path 36a extending straight in the front-rear direction and communicating with the oil mist supply path 12 at an intermediate portion thereof. And a nozzle forming hole 36b extending toward the front end side and opening toward the rear bearing 28. Thus, the oil mist is injected from the rear side into the rear bearing 28 through the oil mist supply passage 12, the supply passage 36a, and the nozzle forming hole 36b.
[0028]
In the following description, the supply path 34a and the nozzle forming hole 34b will be referred to as a nozzle 33, and the supply path 36a and the nozzle forming hole 36b will be referred to as a nozzle 35.
[0029]
A plurality of nozzles 33 of the front cover member 30 are provided around the main shaft. As shown in FIG. 3, each nozzle 33 has a nozzle forming hole 34b with respect to the direction of the main shaft 20 (the left-right direction in FIG. 3). It is provided in a state of being inclined to the downstream side in the rotation direction by an angle θ, and in this embodiment, is provided in a state of being inclined by 25 °. As a result, oil mist is injected obliquely toward the front bearing 22 from the upstream side to the downstream side in the rotational drive direction of the main shaft 20 (in the direction of the solid arrow in the figure; from the lower side to the upper side in the figure). It is configured. On the other hand, similarly to the nozzle 33 of the front cover member 30, a plurality of nozzles 35 of the rear cover member 32 are provided around the main shaft, and although not shown, the nozzle formation holes 36b are oriented in the direction of the main shaft 20 ( (In the figure, the left-right direction), and is provided in a state of being inclined to the downstream side in the rotational direction by an angle θ (25 ° in the present embodiment), whereby the upstream side in the rotational drive direction of the main shaft 20 with respect to the rear bearing 28 is provided. It is configured to inject oil mist in an oblique direction from the downstream toward the downstream side.
[0030]
According to the spindle head as described above, while the spindle 20 is being driven, oil mist is supplied (sprayed) from the nozzles 33 and 35 to the front and rear bearings 22 and 28, thereby seizing the bearings 22 and 28. Is prevented. At this time, since the oil mist is sprayed obliquely from the upstream side to the downstream side in the rotational driving direction of the main shaft 20 as described above, even if the rotational speed of the main shaft 20 increases, the oil mist is sprayed on the bearings 22 and 28. The relative speed of the mist is less likely to be deviated in the reverse direction of rotation, and the rotation resistance of the main shaft is less likely to occur. Further, the spray pressure of the oil mist also acts as a rotation assisting force of the main shaft 20.
[0031]
Therefore, the loss of the motor output (torque) due to the spray of the oil mist can be reduced, so that the motor output can be more effectively used for processing the work.
[0032]
In particular, in this spindle head, a plurality of nozzles 33 and 35 are provided corresponding to the front and rear bearings 22 and 28, respectively, and oil mist is blown from a plurality of locations to the bearings 22 and 28. Has a high rotation assisting effect, and the loss of motor output can be further reduced.
[0033]
The above-described spindle head is an example of a processing apparatus to which the lubrication structure of the spindle bearing according to the present invention is applied, and a specific configuration thereof can be appropriately changed without departing from the gist of the present invention. The following configuration can be adopted.
[0034]
(1) In the present embodiment, each of the nozzles 33 and 35 (nozzle forming holes 34b and 36b) is provided so as to be inclined at 45 ° to the direction of the main shaft 20 downstream in the rotation direction. The angle θ of the nozzle forming holes 34b and 36b with respect to the angle may be appropriately set within a range of, for example, 0 ° <θ <90 °. When the Dmn value is 2,000,000 or more, the angle θ is preferably set within a range of 10 ° to 30 °. Is good. This is because if it is less than 10 °, the spraying speed of the oil mist may be lower than the revolving speed of the ball. Conversely, if it is more than 30 °, the oil mist breaks the wall of the air generated around the ball. There is no possibility. The Dmn value is the ball pitch diameter of the bearing (mm) × the number of rotations (min ⁻¹ ).
[0035]
(2) In the present embodiment, the spray angle of the oil mist to the front and rear bearings 22 and 28 (the angle θ of the nozzle forming holes 34b and 36b) is the same, but the type (structure) of the front and rear bearings 22 and 28 is different. Accordingly, oil mist may be sprayed on the front and rear bearings 22 and 28 at different angles.
[0036]
(3) Regardless of the direction of the spindle 20, the present invention is also applicable to a machining apparatus that performs machining with a tool attached to the spindle 20 facing downward, for example.
[0037]
(4) The spindle head according to the embodiment has a so-called direct drive structure in which the rotor 24 constituting the motor is directly fixed to the spindle 20 and the stator 14 is arranged around the rotor 24. The output shaft of the motor is located behind the spindle. The present invention is also applicable to a spindle head having a drive structure directly connected to the end.
[0038]
(5) In the embodiment, the oil mist is supplied to the bearings 22 and 28 from the outside (the front side of the front bearing 22 and the rear side of the rear bearing 28). Oil mist may be supplied from the rear side of the front bearing 22 and the front side of the rear bearing 28), or oil mist may be supplied to the bearings 22 and 28 from both inside and outside.
[0039]
【The invention's effect】
As described above, the present invention is a lubricating structure for a bearing portion of a machining apparatus having a tool mounting portion at a front end and having a main shaft rotatably supported via a rolling bearing, wherein the main shaft is provided with respect to the bearing. A nozzle for supplying lubricating oil is provided so that the lubricating oil is sprayed from the upstream side to the downstream side in the rotational driving direction of the main shaft. As a result, the mechanical loss of the motor output due to the spraying of the lubricating oil can be effectively reduced, and as a result, the motor output can be more effectively used for processing the workpiece.
[Brief description of the drawings]
FIG. 1 is a sectional side view showing a spindle head in an internal grinding machine (processing apparatus) to which the present invention is applied.
FIG. 2 is an enlarged view of FIG. 1 showing a part of a front bearing of a main shaft.
FIG. 3 is a sectional view taken along line AA of FIG. 2 showing a shape of a nozzle for injecting oil mist.
[Explanation of symbols]
Reference Signs List 10 Casing 11 Oil mist supply port 12 Oil mist supply passage 20 Main shaft 22 Front bearing 28 Rear bearing 30 Front cover member 32 Rear cover members 33, 35 Nozzles 34a, 36a Supply paths 34b, 36b Nozzle forming holes

Claims (5)

A lubricating structure for the bearing of a machining apparatus having a tool mounting portion at a front end and rotatably supported by a casing via a bearing, and rotating the main shaft by a motor. A nozzle for supplying lubrication oil from the upstream to the downstream in the rotational driving direction of the main shaft with respect to the bearing. Lubrication structure. The bearing lubrication structure for a main shaft according to claim 1,
The bearing of the main shaft, wherein the nozzle is configured to supply the lubricating oil in a direction inclined in a range of 10 ° to 30 ° to the downstream side in the rotation direction of the main shaft with respect to the direction of the main shaft. Lubrication structure. The bearing lubrication structure for a main shaft according to claim 1 or 2,
The processing device includes a cover member that is attached to the casing and covers the bearing from the direction of the main shaft. The cover member includes a nozzle forming hole that opens toward the bearing, and a nozzle forming hole that opens toward the bearing. A bearing lubrication structure for a main shaft, wherein a supply passage for supplying lubricating oil is formed in the hole. The bearing lubrication structure for a spindle according to any one of claims 1 to 3,
A bearing lubrication structure for a spindle, wherein a plurality of nozzles are provided around the spindle as the nozzles. The bearing lubrication structure for a spindle according to any one of claims 1 to 4,
A rotor lubrication for the main shaft, wherein a rotor constituting the motor is fixed to an intermediate portion of the main shaft, and both front and rear sides of the rotor fixing portion are rotatably supported by the bearings. Construction.

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