Spindle device, grinding device, and cutting machining device

Abstract

While a rotary shaft is stationary or rotating at a low speed, a lip part is brought into pressure contact with a contact surface provided to a housing to seal between the housing and the rotary shaft on the device-distal-end side, and while the rotary shaft is rotating at least at a prescribed rotation speed exceeding the low speed, the lip part is separated from the contact surface by centrifugal force associated with the rotary shaft to release the sealing. The present invention comprises a deformation suppression member that limits deformation of a lip part during rotation of a rotary shaft. The rotary shaft is provided with an impeller that suctions external air and force-feeds the air into a housing. The housing is provided with an outside-diameter-side passage path through which the air suctioned into the device from the outside by the rotation of the impeller flows within the device. An air discharge path via which air is discharged at least from the device-distal-end side communicates with the outside-diameter-side passage path, and a sealing device is disposed in the air discharge path. When the lip part of the sealing device is separated from the contact surface, the air pressure of the air flowing through the outside-diameter-side passage path acts in addition to the centrifugal force during the rotation of the rotary shaft.

Description

Spindle device, grinding device, and cutting device

[0001] The present invention relates to a spindle device, a grinding device, and a cutting device.

[0002] Conventionally, in a device that rotates a tool for machining, a spindle device in which a tool is detachably attached to a rotatable spindle is known. The spindle device generally includes a rotating part supported by bearings and a fixed part other than this rotating part. And various machining tools (for example, grindstones, cutting tools, etc.) are attached to the tip of the rotating shaft that constitutes the rotating part, and machining (polishing, cutting, etc.) is performed on the workpiece with these machining tools.

[0003] Therefore, there was a risk that foreign matter such as machining fluid and chips would enter the spindle device during machining from the clearance between the rotating part and the fixed part. If foreign matter enters the spindle device in this way, the rotation of the rotating shaft may not be smooth, a large load may be applied, and the spindle device may be damaged.

[0004] Conventionally, in order to prevent the intrusion of coolant, chips, etc. inside, there is a structure in which an air chamber is provided in the housing so that air can be discharged from this air chamber to the outside of the housing. In this case, a lip seal is externally fitted and supported on the spindle (rotating shaft) in the air chamber, and the lip of the lip seal is brought into contact with the inner peripheral surface of the housing, and the lip is configured to be separated from the inner peripheral surface of the housing by centrifugal force as the rotating shaft rotates (Patent Document 1).

[0005] In the invention described in Patent Document 1, when the spindle rotation is stopped and no air is supplied to the air chamber, the gap between the inner surface of the housing and the outer surface of the spindle is sealed by a lip within the air chamber. Therefore, coolant, chips, etc. that enter the air chamber through the gap between the housing and the spindle are prevented from entering the bearing side beyond the air chamber by the lip seal. Furthermore, when the spindle is rotating, the centrifugal force accompanying the rotation of the spindle ensures that the entire lip of the lip seal separates reliably from the inner surface of the housing. In this state, the air supplied to the air chamber from the air supply passage is discharged to the outside of the housing through a gap formed between the housing and the spindle on the tip side of the air chamber, and the pressure of this air prevents coolant, chips, etc. from entering the inside of the spindle head through this gap.

[0006] In addition, conventional cutting devices have an air seal exhaust passage provided between a mounting member for attaching a cutting blade and a spindle housing, and a sealing member that can open and close the outlet of this air seal exhaust passage (Patent Document 2).

[0007] In the invention described in Patent Document 2, when air is supplied to the air bearing, the air is ejected through the gap between the spindle housing and the spindle on the mounting member side, and through the air seal exhaust passage, thereby preventing foreign matter from entering due to the pressure of the air. On the other hand, when air is not supplied to the air bearing and the air seal is not functioning, the outlet of the air seal exhaust passage can be blocked by the sealing member. This prevents foreign matter from entering the air seal exhaust passage from the outside.

[0008] Furthermore, conventionally, there is a spindle sealing structure in a machine tool in which a gap exists between the spindle (rotating shaft) or a member fixed to the front end of the spindle and the front end of the shaft holding member (Patent Document 3). In this case, a pressurized section is provided that pressurizes gas into the gap from the inside of the shaft holding member as the spindle rotates, a secondary pressurized section that pressurizes gas as the spindle rotates, and a bias passage is provided that guides the gas pressurized by the secondary pressurized section to the upstream side of the pressurized section, bypassing the bearing member.

[0009] In the device described in Patent Document 3, the pumping action in the pumping section is reinforced, and the spray pressure from the gap is effectively increased. Moreover, the gas pumped in the auxiliary pumping section does not pass through the space inside the bearing member, and therefore, even when the bearing member is lubricated with grease, deterioration of the grease can be prevented.

[0010] Japanese Patent Publication No. 2007-223008, Japanese Patent Publication No. 2005-59151, Japanese Patent No. 3745584

[0011] In Patent Documents 1, 2, and 3, the air supply port of the air supply passage inside the housing communicates with an air supply means provided outside the housing. Specifically, in Patent Document 1, an air supply passage for introducing air into an air chamber is provided inside the housing, and the air supply passage opens on the outer surface of the housing. This opening serves as the air supply port, and air is supplied from an air supply device outside the housing. In Patent Document 2, the air supply passage opens at the rear end of the housing, and air is supplied from an air supply means outside the housing. Furthermore, in Patent Document 3, a passage for introducing air is formed in the casing (housing), and this passage communicates with the outside via a hose or the like. Therefore, air is introduced into the housing from the outside via the passage. When compressed air is introduced into the housing from the outside in this way, there is a problem that energy loss increases.

[0012] Incidentally, by installing a contact seal in the gap between the rotating and stationary parts of the spindle device, it is possible to effectively prevent the intrusion of processing fluids and chips into the device. When installed in devices with relatively high rotational speeds, such as spindle devices, contact seals are generally installed in the stationary part of the spindle device. The contact seal installed in the stationary part physically eliminates the gap, preventing the intrusion of processing fluids and chips into the spindle device, thus eliminating the need to use compressed air as described above. However, the frictional resistance of the contact seal hinders the smooth rotational movement of the rotating part, and the increased rotational torque increases the power consumption required to rotate the spindle device. Furthermore, the frictional resistance of the contact seal generates heat in the rotating and stationary parts, which can lead to abnormal wear of the contact seal and a reduced lifespan, as well as concerns that the heat may be transmitted to the bearings, causing abnormal temperature increases in the bearings and potentially leading to premature bearing failure.

[0013] Therefore, the present invention provides a spindle device, a grinding device, and a cutting device that can reduce power consumption and environmental impact, effectively prevent the intrusion of processing fluids and chips into the device, and effectively prevent a reduction in lifespan due to abnormal wear of sealing members.

[0014] The first spindle device of the present invention is a spindle device comprising a rotating shaft on which an object can be mounted at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein when the rotating shaft is stationary or rotating at a low speed, the lip portion of the sealing device presses against a contact surface provided on the housing, sealing the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft exceeds a predetermined rotational speed beyond the low speed, the lip portion separates from the contact surface due to the centrifugal force associated with the rotating shaft, releasing the seal, and when the rotating shaft rotates... The device is equipped with a deformation-restricting member to limit the deformation of the lip portion, and the rotating shaft is provided with an impeller that draws in external air and pressurizes the air into the housing. The housing is provided with an outer diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, and an air discharge passage that discharges air from the front end of the device is connected to the outer diameter passage. The sealing device is positioned in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the outer diameter passage acts in addition to the centrifugal force when the rotating shaft rotates.

[0015] The second spindle device of the present invention is a spindle device comprising a rotating shaft on which an object can be mounted at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein when the rotating shaft is stationary or rotating at a low speed, the lip portion of the sealing device presses against a contact surface provided on the housing, sealing the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft exceeds a predetermined rotational speed beyond the low speed, the centrifugal force accompanying the rotating shaft causes the lip portion to separate from the contact surface, releasing the seal and the rotation of the rotating shaft The device is equipped with a deformation-restricting member that limits the deformation of the lip portion, and the rotating shaft is provided with an impeller that draws in external air and pressurizes the air into the housing. The rotating shaft is provided with an inner diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, and an air discharge passage that discharges air from the front end of the device is connected to the inner diameter passage. The sealing device is positioned in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the inner diameter passage acts in addition to the centrifugal force when the rotating shaft rotates.

[0016] A third spindle device of the present invention is a spindle device comprising a rotating shaft on which an object can be mounted at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein when the rotating shaft is stationary or rotating at a low speed, the lip portion of the sealing device presses against a contact surface provided on the housing to seal the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft rotates at a predetermined rotational speed exceeding the low speed, the centrifugal force associated with the rotating shaft causes the lip portion to separate from the contact surface, thereby releasing the seal, and the sealing device is provided with a deformation suppression member that limits the deformation of the lip portion when the rotating shaft rotates, and external air is drawn into the rotating shaft An impeller for pressurizing air is provided inside the housing, and the housing is provided with an outer diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, and the rotating shaft is provided with an inner diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, and an air discharge passage for discharging air from the tip side of the device is connected to the outer diameter passage and the inner diameter passage, and the sealing device is arranged in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the outer diameter passage and the inner diameter passage acts in addition to the centrifugal force when the rotating shaft rotates.

[0017] The deformation in the first, second, and third spindle devices refers to deformation due to damage or deformation that does not return to its original shape due to plastic deformation. In other words, in the absence of a deformation suppression member, if a force (external force) that separates the contact surface is applied and then the force (external force) that causes separation is removed, the lip portion will not return to its original state due to its restoring force, and there is a risk that the air discharge passage will open. In contrast, the deformation that occurs when the lip portion separates from the contact surface that is pressed against the housing, causing the air discharge passage to open and allowing the fluid to be ejected from the axial front end of the housing, is deformation due to elastic deformation. When the force (external force) that causes this deformation is removed, the lip portion will return to its original state due to its restoring force, thus blocking the air discharge passage. For this reason, when the seal device is equipped with a deformation suppression member, deformation that does not return to its original shape due to plastic deformation, etc., is restricted, while deformation due to elastic deformation is permitted.

[0018] Therefore, in the first, second, and third spindle devices according to the present invention, the air discharge passage is blocked when the rotating shaft is stationary or rotating at a low speed, thus preventing foreign matter such as processing fluid and chips from entering the sealing device. Note that low-speed rotation refers to rotation at a speed in which the lip portion does not separate from the contact surface. Furthermore, even when the rotating shaft is rotating at a predetermined rotational speed or higher than the low-speed rotation, the fluid is ejected from the axial front end of the housing, thus preventing foreign matter from entering the sealing device. The predetermined rotational speed is a speed exceeding the low-speed rotation, such that the lip portion separates from the contact surface. For example, the predetermined rotational speed is 5000 min. -1 The above is preferable. Furthermore, since the deformation suppressing member is fitted into the circumferential groove of the sealing member, deformation of the lip portion (deformation that does not return to its original shape due to plastic deformation, etc.) can be suppressed.

[0019] Thus, in devices that have an air discharge passage that discharges air from the front end, it is possible to prevent foreign matter from entering the sealing device whether the rotating shaft is rotating or not, thereby preventing the device from being shortened due to foreign matter entering the device.

[0020] By mounting an impeller on the rotating shaft that draws in external air and pressurizes it into the housing, the impeller rotates in conjunction with the rotation of the shaft, allowing air to be drawn into the device from the outside. This eliminates the need to introduce air from outside the housing, and ensures a stable supply of external air into the device. In other words, since there is no need to maintain a high air pressure inside the device, air consumption can be reduced. In this case, the impeller can be of centrifugal, axial flow, or mixed flow type.

[0021] The grinding apparatus according to the present invention is a grinding apparatus equipped with the spindle device, wherein the mounted object attached to the tip of the rotating shaft is a grinding wheel. In the grinding apparatus according to the present invention, whether the rotating shaft is stopped or rotating, the inflow of foreign matter into the air discharge passage can be prevented, and the inflow of foreign matter into the grinding apparatus can be avoided.

[0022] The cutting apparatus according to the present invention is a cutting apparatus equipped with the spindle device, wherein the mounted object attached to the tip of the rotating shaft is a cutting tool. In the cutting apparatus according to the present invention, whether the rotating shaft is stopped or rotating, the inflow of foreign matter into the air discharge passage can be prevented, and the inflow of foreign matter into the cutting apparatus can be avoided.

[0023] This invention prevents foreign matter from entering the sealing device whether the rotating shaft is rotating or not, thus preventing the device from being shortened due to foreign matter intrusion. Furthermore, it can suppress deformation of the lip portion (deformation that does not return to its original shape due to plastic deformation, etc.), thereby extending the lifespan of the sealing member. In particular, during rotation, the lip portion separates from the lip contact surface of the mating side (separation in this case is due to elastic deformation), eliminating frictional resistance caused by contact or pressure contact. This suppresses heat generation in the rotating part (rotating shaft side) and the fixed part (housing side), effectively preventing premature failure of components inside the device (for example, bearings that rotatably support the rotating shaft) due to temperature rise. Moreover, when the rotating shaft is stopped, there is no need to eject fluids such as compressed air, thus reducing the consumption of fluids such as compressed air and contributing to cost reduction. In addition, as the impeller rotates along with the rotation of the rotating shaft, air can be drawn into the device from the outside, thus reducing air consumption and power consumption, and contributing to environmental load reduction.

[0024] This is a cross-sectional view of the first spindle device according to the present invention. This is a simplified diagram of the impeller of the first spindle device. This is an enlarged cross-sectional view showing the airflow drawn into the inside of the first spindle device. This is an enlarged cross-sectional view showing the sealing device with the rotating shaft not rotating. This is an enlarged cross-sectional view showing the sealing device with the rotating shaft rotating. This is a cross-sectional view of the second spindle device according to the present invention. This is a simplified diagram of the impeller of the second spindle device. This is a cross-sectional view of the third spindle device according to the present invention. This is a simplified diagram of the impeller of the third spindle device.

[0025] Embodiments of the present invention will be described below with reference to Figures 1 to 8. Figure 1 is a cross-sectional view of the spindle device according to the present invention, Figure 2 is a simplified view of the impeller, and Figure 3 is an enlarged cross-sectional view of Figure 1. The spindle device comprises a rotating shaft 1 and a housing 5 that rotatably supports the rotating shaft 1 via a pair of bearings 2, 2 at the front end and a pair of bearings 3, 3 at the rear end. The rotating shaft 1 is rotated around its axis by the rotational driving force of an external power source such as a motor (not shown) transmitted via a power transmission mechanism 4. The power transmission mechanism 4 can be a known or publicly used gear mechanism, belt mechanism, or coupling mechanism, etc.

[0026] On the reaction power transmission mechanism side of the rotating shaft 1 (i.e., the front end), the mounted object is directly or indirectly attached to the mounting portion 1a. In addition, the housing 5 has an outer diameter passage 6 through which fluid (air) flows, and the rotating shaft 1 has an inner diameter passage 7 through which fluid (air) flows. Here, the mounted object refers to various processing tools (for example, grinding wheels and cutting tools, etc.), and in this spindle device, these processing tools are used to perform processing (polishing, cutting, etc.) on the workpiece.

[0027] Incidentally, the housing 5 comprises a front main body portion 5a1 made of a cylindrical body, a rear main body portion 5a2 connected to the front main body portion 5a1, a lid member 5b that closes the front opening of the front main body portion 5a1, and a lid member 5c that closes the rear opening of the rear main body portion 5a2. The rear main body portion 5a2 comprises a front small inner diameter portion 8 having the same inner diameter as the front main body portion 5a1, and a rear large inner diameter portion 9 having a larger inner diameter than the small inner diameter portion 8. The lid member 5b is attached to the rotating shaft 1 side and rotates integrally with the rotating shaft 1. On the other hand, the lid member 5c is attached to the large inner diameter portion 9 of the rear main body portion 5a2 of the housing 5 and is integrated with it, and does not rotate with the rotation of the rotating shaft 1. This lid member 5c is made of a flat disc-shaped body with an axial hole 5c1 provided therein and is fixed so as to close the rear opening of the rear main body portion 5a2 of the housing 5. As will be described later, the axial hole 5c1 serves as an air intake for drawing in outside air.

[0028] A power transmission mechanism 4, which can be composed of a gear mechanism, a belt mechanism, or a coupling mechanism, is arranged inside the housing 5, specifically inside the large inner diameter portion 9 of the rear main body portion 5a2. The power transmission mechanism 4 is provided with through holes 80 that serve as air passages. The impeller 70 is attached to the rotating shaft 1 at the rear end of the power transmission mechanism 4.

[0029] The impeller 70 of the spindle device of the first embodiment shown in Figure 1 is a centrifugal impeller 71 equipped with a number of curved blades 71a, as shown in Figure 2. Specifically, the centrifugal impeller 71 comprises a disc-shaped main plate 72a fixed to the rotating shaft 1, a plurality of blades 71a provided on the main plate 72a and arranged at equal intervals in the rotational direction indicated by the arrows in Figure 2, and a side plate 72b spanning between the ends of each blade 71a on the opposite side of the main plate 72a. In a centrifugal impeller, air enters from the axial direction and is expelled perpendicular to the shaft.

[0030] Incidentally, as shown in Figure 1, the outer diameter passage 6 has an axial first passage 6a provided in the front main body portion 5a1 of the housing 5, an axial second passage 6b provided in the rear main body portion 5a2 and continuous with the axial first passage 6a, and a radial passage 6c extending radially inward from the tip of the axial first passage 6a.

[0031] Furthermore, as shown in Figure 3, the front pair of bearings 2a, 2b and the rear pair of bearings 3a, 3b each consist of inner rings 2a1, 2b1, 3a1, 3b1, outer rings 2a2, 2b2, 3a2, 3b2, and balls 2a3, 2b3, 3a3, 3b3 interposed between the inner and outer rings. Between the front pair of bearings 2a, 2b and between the rear pair of bearings 3a, 3b, there are spacers 41a, 41b interposed between the inner rings and spacers 42a, 42b interposed between the outer rings.

[0032] The rear end surface of the front main body portion 5a1 of the housing 5 is in contact with the front end surface of the rear main body portion 5a2. Also, as shown in Figure 3, a stepped portion 10 is provided on the front inner diameter portion of the rear main body portion 5a2, and this stepped portion 10 is in contact with the outer ring 3b2 of the last row bearing 3 (3b) from the axial and radial directions. In addition, a bearing inner ring retainer 38 is interposed between the last row bearing 3 (3b) and the power transmission mechanism 4.

[0033] As shown in Figure 3, the front end surface of the housing 5 is provided with a circumferential notch 30 into which one of the lid members 5b is fitted. In this case, the circumferential notch 30 consists of a large-diameter portion 30a on the opening side and a small-diameter portion 30b on the inner side, and the front (tip side) lid member 5b is rotatably fitted into the large-diameter portion 30a.

[0034] The front cover member 5b has a disc-shaped main body 31 and an inner flange 32 on the inner end surface of the main body 31. The main body 31 is fitted into the large diameter portion 30a of the notch 30 with the inner flange 32 fitted into the small diameter portion 30b. A bearing inner ring retainer 33 is interposed between the frontmost bearing 2 (2a) and the cover member 5b. This bearing inner ring retainer 33 is provided with a hole 33a that communicates with the radial passage 7b in front of the inner diameter side passage path 7 of the rotating shaft 1, which will be described later. This hole 33a communicates with the space 34 between the frontmost bearing 2a and the bearing inner ring retainer 33. In this case, the radial passage 6c of the outer diameter side passage path 6 communicates with the space 34.

[0035] The inner diameter passage 7 comprises an axial passage 7a arranged along the axis of the rotating shaft 1, and a radial passage 7b extending radially from the tip of the axial passage 7a. This radial passage 7b communicates with the space 34 between the frontmost bearing 2a and the bearing inner ring retainer 33.

[0036] Furthermore, as shown in Figures 4A and 4B, a sealing member 51 is attached to the lid member 5b as a sealing device. The sealing member 51 consists of a main body portion 51a made of a ring member and a ring-shaped lip portion 51c connected to the main body portion 51a via a circumferential groove 51b. In other words, a so-called V-ring is used as the sealing member 51 in this case.

[0037] In this case, a ring-shaped groove 53 is formed on the inner surface of the lid member 5b, and the main body portion 51a of the sealing member 51 is fitted into this groove 53, with the lip portion 51c having close contact or in contact with the front main body portion 5a1 of the housing 5. The contact area of ​​the lip portion 51c is the contact surface 30b1, which is the bottom surface of the small diameter portion 30b on the inner side of the circumferential notch portion 30 of the front main body portion 5a1 of the housing 5. Furthermore, the lip portion 51c is inclined at a predetermined angle with respect to the axial direction of the housing. In this case, the inclination angle θ is set to, for example, 50° to 60°. The tip of the lip portion 51c is an annular end surface 51c1 that makes surface contact with the contact surface 30b1 of the front main body portion 5a1 of the housing 5.

[0038] Furthermore, a deformation suppression member (deformation suppression ring) 55 is fitted to the circumferential groove 51b of the sealing member 51, receiving the lip portion 51c and limiting the deformation of the lip portion when the rotating shaft rotates. Here, deformation refers to deformation due to damage or deformation that does not return to its original shape due to plastic deformation. In other words, in the absence of the deformation suppression member 55, if a force (external force) that separates the lip portion 51c is applied and then the force (external force) that separates the lip portion 51c is removed, the lip portion 51c will not return to its original state by its restoring force, and there is a risk that the air discharge passage will remain open. In contrast, the deformation that occurs when the lip portion 51c separates from the contact surface that is pressed against the housing 5, causing the air discharge passage 61 to open and allowing the fluid to be ejected from the axial front end of the housing 5 is deformation due to elastic deformation, and once the force (external force) that causes this deformation is removed, the lip portion 51c will return to its original state by its restoring force, thus blocking the air discharge passage 61. Therefore, when the deformation suppressing member 55 is fitted into the circumferential groove 51b of the sealing member 51, deformation that does not return to the original shape due to plastic deformation, etc., is restricted, while deformation due to elastic deformation is permitted. The deformation suppressing member 55 consists of a ring body 55a and a sub-part 55b connected to the inner end face of the outer diameter side of the ring body 55a, with the inner diameter portion of the ring body 55a fitting into the circumferential groove 51b. For this reason, the outer shape of the inner diameter portion of the ring body 55a is the same shape as the inner shape of the circumferential groove 51b. The deformation suppressing member 55 is also fixed to the lid member 5b via a fastener 56. In this case, the fixing device 56 consists of a screw member 58 inserted through a through hole 57 provided in the lid member 5b. The male threaded tip 58a of the screw member 58 is screwed into the screw hole 59 of the deformation suppressing member 55, and the head 58b of the screw member 58 fits into a recess 57a provided in the opening of the through hole 57, thereby fixing the deformation suppressing member 55 to the lid member 5b. As a result, the deformation suppressing member 55 receives the portion of the lip portion 51c that is omitted from the tip. A space 60a is provided on the inner diameter side of the lip portion 51c through which fluid from the space 34 flows in.

[0039] The sealing member 51 seals the air discharge passage 61 for fluid ejection, which is provided at the axially forward end of the housing 5. In this case, the air discharge passage 61 for fluid ejection is formed by the gap between the bottom of the notch 30 and the outer diameter end face of the notch 30, in the range of the sealing member 51, the deformation suppressing member 55, the inner flange 32, the outer diameter side of the inner flange 32, and the outer diameter end of the lid member 5b.

[0040] By the way, if a machining tool (for example, a grinding wheel or cutting tool) is attached to the tip of the rotating shaft 1 of the spindle device shown in Figures 1 and 3, it will constitute a turning device or a cutting device. In this case, since no fluid is supplied (no air is pumped) to the outer diameter passage 6 of the housing 5 or the inner diameter passage 7 of the rotating shaft 1, the air discharge passage 61 for fluid ejection is sealed by the sealing member 51, so that foreign matter does not enter the device.

[0041] Furthermore, when the rotating shaft 1 is driven to rotate, the impeller 70 rotates, drawing air into the housing 5 through the axial hole 5c1 of the cover member 5c, and supplying it to the outer diameter side passage 6 (axial second passage 6b) of the housing 5 and the inner diameter side passage 7 (axial passage 7a) of the rotating shaft 1. The fluid flows into the inner diameter side passage 7 through through holes 80 provided in the pulleys of the power transmission mechanism 4. The fluid that has entered the rotating shaft 1 and the housing 5 flows into the space 60a through the space 34. The fluid that has entered the space 60a pushes up the lip portion 51c. Also, as the rotating shaft 1 rotates, centrifugal force pushes up the tip of the lip portion 51c, acting to separate the tip of the lip portion 51c from the contact surface. The separation here is due to deformation caused by elastic deformation, and when this deforming force is released, the restoring force of the lip portion 51c returns it to its original state, causing the lip portion 51c to contact the contact surface 30b1 and block the air discharge passage 61.

[0042] Therefore, the lip portion 51c is separated from the tip end portion from the contact surface, the seal member 51 is in an open state, and the fluid that has entered the space portion 60a flows through the air discharge passage 61 and is jetted out of the apparatus from the jet port of the air discharge passage 61. In this case, since the jet port of the air discharge passage 61 opens outward along the axial direction of the rotation axis, the fluid that has entered the air discharge passage 61 is jetted forward in the axial direction of the housing 5.

[0043] Therefore, in the state where the rotation shaft 1 is rotating, the fluid is jetted outward, and thereby, the intrusion of foreign matter into the apparatus can be prevented.

[0044] In the spindle apparatus according to the present invention, since the air discharge passage 61 is blocked during the rotation shaft stationary state or low-speed rotation, the intrusion of foreign matter such as machining fluid and chips into the seal apparatus can be prevented. Here, the low-speed rotation means the rotation at a rotational speed at which the lip portion does not separate from the contact surface. Further, in the state where the rotation shaft 1 is rotating at a predetermined rotational speed or higher exceeding the low-speed rotation, the fluid jets out from the front end side in the axial direction of the housing 5, and thus, even in this state, the intrusion of foreign matter into the seal apparatus can be prevented. The predetermined rotational speed exceeds the low-speed rotation and is a speed at which the lip portion separates from the contact surface. As the predetermined rotational speed, for example, 5000 min -1 or more is preferable. Further, since the deformation suppressing member 55 is fitted into the circumferential groove 51b of the seal member 51, the deformation (deformation that does not return to the original shape due to plastic deformation or the like) of the lip portion 51c can be suppressed. That is, in a state without the deformation suppressing member 55, after the force (external force) for separating from the contact surface acts and deformation occurs, even if the force (external force) for causing deformation is removed, the lip portion 51c does not return to the original state by its restoring force, and there is a possibility that the air discharge passage 61 becomes open. Therefore, in the state where the deformation suppressing member 55 is fitted into the circumferential groove 51b of the seal member 51, the deformation (deformation that does not return to the original shape due to plastic deformation or the like) is regulated, and the deformation due to elastic deformation is allowed.

[0045] Even when the rotating shaft 1 is rotating or not rotating, the present invention can prevent foreign matter from entering the sealing device, and can prevent the shortening of the life of the device due to the intrusion of foreign matter into the device. In addition, since deformation (deformation that does not return to the original shape due to plastic deformation or the like) of the lip portion 51c can be suppressed, the life of the seal member 51 can be extended. In particular, during rotation, the lip portion 51c will be separated from the mating lip contact surface, and there will be no frictional resistance caused by contact or pressure contact. Heat generation of the rotating part (rotating shaft side) and the fixed part (housing side) is suppressed, and early breakage of bearings and the like due to temperature rise of members in the device (for example, bearings that support the rotating shaft rotatably) can be effectively prevented. Furthermore, when the rotating shaft 1 is stopped, fluid ejection such as compressed air is not required, so the consumption of fluid such as compressed air can be suppressed, contributing to cost reduction.

[0046] The deformation suppressing member 55 can be configured to be mounted on the rotating shaft side and fixed to the lid member 5b that closes the axial end opening of the housing 5 via a fixing tool 58. By configuring in this way, the deformation suppressing member 55 can be stably fixed to the lid member 5b, and the function (deformation suppressing function) as the deformation suppressing member 55 can be effectively exerted.

[0047] In addition, by providing an impeller 70 on the rotating shaft 1 that sucks external air and pumps the air into the housing, as the rotating shaft 1 rotates, the impeller 70 rotates and external air can be sucked into the device. Thereby, it is not necessary to introduce air from outside the housing, and external air can be stably sucked into the device. That is, since it is not necessary to increase the air pressure inside the device, the consumption of air can be reduced, the power consumption can be reduced, and the environmental load can be reduced.

[0048] Next, Figure 5 shows another embodiment (second spindle device), in which an axial flow impeller 73 as shown in Figure 6 is used. As shown in Figure 6, the axial flow impeller 73 comprises an annular base 74 fixed to the rotating shaft 1, and a plurality of blades 73a arranged radially around the base 74 and spaced equally in the rotational direction indicated by the arrows in Figure 6. The axial flow impeller draws air in from the axial direction and delivers air parallel to the axial direction. Even with such an axial flow impeller 73, as the rotating shaft 1 rotates and the impeller 70 rotates, air is drawn into the housing 5 through the axial hole 5c1 of the cover member 5c and flows into the space 34 via the outer diameter passage 6 and the inner diameter passage 7. The air that flows into the space 34 enters the air discharge passage 61 which has a sealing device.

[0049] The spindle device shown in Figure 5 has the same configuration as the spindle device shown in Figure 1, and in Figure 5, components identical to those in Figure 1 are denoted by the same reference numerals, and their descriptions are omitted. Therefore, the spindle device shown in Figure 5 has the same effects and functions as the spindle device shown in Figure 1.

[0050] Figure 7 shows another embodiment (third spindle device), in which a mixed-flow impeller 75 as shown in Figure 8 is used. As shown in Figure 8, the mixed-flow impeller 75 is fixed to the rotating shaft and comprises a base 76 having an inclined surface that widens in diameter from the suction side to the discharge side, and a plurality of blades 75a arranged at equal intervals in the rotational direction indicated by the arrows in Figure 8 on the inclined surface of the base 76. The blades 75a are inclined at a constant angle with respect to the rotating shaft. The mixed-flow impeller draws air in from the axial direction and discharges air at an angle to the shaft, and has intermediate performance between a centrifugal impeller and an axial-flow impeller. Even when using such a mixed-flow impeller 75, as the rotating shaft 1 rotates and the impeller 70 rotates, air is drawn into the housing 5 through the axial hole 5c1 of the cover member 5c and flows into the space 34 through the outer diameter passage 6 and the inner diameter passage 7. Furthermore, the air that flows into space 34 enters the air discharge passage 61 which has a sealing device.

[0051] The spindle device shown in Figure 7 has the same configuration as the spindle devices shown in Figures 1 and 5, and in Figure 7, components identical to those in Figures 1 and 5 are denoted by the same reference numerals, and their descriptions are omitted. Therefore, the spindle device shown in Figure 7 has the same effects and functions as the spindle devices shown in Figures 1 and 5.

[0052] Even with the spindle apparatus shown in Figures 5 and 7, a grinding device can be constructed by attaching a grinding wheel or the like as a processing tool to the tip of the rotating shaft. Whether the rotating shaft 1 is stopped or rotating, foreign matter can be prevented from entering the air discharge passage, thus preventing foreign matter from entering the grinding device.

[0053] Furthermore, even with the spindle device shown in Figures 5 and 7, a cutting tool can be attached to the tip of the rotating shaft to constitute a cutting machine. This prevents foreign matter from entering the air discharge passage whether the rotating shaft 1 is stopped or rotating, thus avoiding the inflow of foreign matter into the cutting machine.

[0054] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. In the above embodiments, when the lip portion separates from the contact surface in which it is pressed against the housing, it was due to centrifugal force and fluid pressure, but it may separate due to only one of centrifugal force or fluid pressure. In other words, there are three cases: when both centrifugal force and fluid pressure are used, when only centrifugal force is used, and when only fluid pressure is used. Incidentally, a so-called V-ring was used as the sealing member, and there are A-type, S-type, L-type, and E-type V-rings, and any type can be used. Furthermore, the material can be nitrile rubber (NBR), fluororubber (FPM), chloroprene rubber (CR), ethylene propylene rubber (EPDM), ethylene acrylic rubber (EACM), silicone rubber (Q), etc.

[0055] A spindle device comprises a rotating part supported by bearings and a stationary part other than the rotating part. Grinding wheels, cutting tools, etc., are mounted on the tip of the rotating part.

[0056] 1. Rotating shaft 2. Bearing 3. Bearing 5. Housing 6. Outer diameter passage 7. Inner diameter passage 51. Seal device (sealing member) 51c. Lip section 61. Air discharge passage 70. Impeller 71. Centrifugal impeller 73. Axial flow impeller 75. Mixed flow impeller

Claims

1. A spindle device comprising a rotating shaft capable of mounting an object at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein the sealing device has a lip portion that presses against a contact surface provided on the housing when the rotating shaft is stationary or rotating at a low speed, thereby sealing the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft rotates at a predetermined rotational speed exceeding the low speed, the centrifugal force accompanying the rotating shaft causes the lip portion to separate from the contact surface, thereby releasing the seal, and also includes a deformation suppressing member that limits the deformation of the lip portion when the rotating shaft rotates, and the rotating shaft is provided with an impeller that draws in external air and pressurizes the air into the housing, The spindle device is characterized in that the housing is provided with an outer diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, an air discharge passage for discharging air from the tip side of the device is connected to the outer diameter passage, the sealing device is arranged in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the outer diameter passage acts in addition to the centrifugal force when the rotating shaft rotates.

2. A spindle device comprising a rotating shaft capable of mounting an object at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein the sealing device has a lip portion that presses against a contact surface provided on the housing when the rotating shaft is stationary or rotating at a low speed, thereby sealing the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft rotates at a predetermined rotational speed exceeding the low speed, the centrifugal force accompanying the rotating shaft causes the lip portion to separate from the contact surface, thereby releasing the seal, and also includes a deformation suppressing member that limits the deformation of the lip portion when the rotating shaft rotates, and the rotating shaft is provided with an impeller that draws in external air and pressurizes the air into the housing, A spindle device characterized in that the rotating shaft is provided with an inner diameter passage through which air drawn into the device from the outside by the rotation of the impeller flows inside the device, an air discharge passage for discharging air from the front end of the device is connected to the inner diameter passage, the sealing device is arranged in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the inner diameter passage acts in addition to the centrifugal force during the rotation of the rotating shaft.

3. A spindle device comprising a rotating shaft capable of mounting an object at its tip, a housing that rotatably supports the rotating shaft via a bearing, and a sealing device disposed between the rotating shaft at the tip of the device and the housing, wherein the sealing device has a lip portion that presses against a contact surface provided on the housing when the rotating shaft is stationary or rotating at a low speed, thereby sealing the space between the rotating shaft at the tip of the device and the housing, and when the rotating shaft rotates at a predetermined rotational speed exceeding the low speed, the centrifugal force accompanying the rotating shaft causes the lip portion to separate from the contact surface, thereby releasing the seal, and also includes a deformation suppressing member that limits the deformation of the lip portion when the rotating shaft rotates, and the rotating shaft is provided with an impeller that draws in external air and pressurizes the air into the housing, A spindle device characterized in that the housing is provided with an outer diameter passage for air drawn into the device from the outside by the rotation of the impeller and flowing through the device, the rotating shaft is provided with an inner diameter passage for air drawn into the device by the rotation of the impeller and flowing through the device, an air discharge passage for discharging air from the tip side of the device is connected to the outer diameter passage and the inner diameter passage, the sealing device is arranged in the air discharge passage, and when the lip portion of the sealing device separates from the contact surface, the air pressure of the air that has flowed through the outer diameter passage and the inner diameter passage acts in addition to the centrifugal force when the rotating shaft rotates.

4. The spindle device according to any one of claims 1 to 3, characterized in that the impeller is of the centrifugal, axial flow, or mixed flow type.

5. A grinding apparatus comprising the spindle device described in claims 1 to 4, characterized in that the object mounted on the tip of the rotating shaft is a grinding wheel.

6. A cutting machine comprising the spindle device described in claims 1 to 4, characterized in that the mounted object attached to the tip of the rotating shaft is a cutting tool.

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