JP6850591B2 - Spindle unit - Google Patents

Description

The present invention relates to a spindle unit that rotatably supports a spindle by an air bearing.

In a processing device such as a grinding device, a wafer is processed by rotating a processing tool with a spindle unit (see, for example, Patent Document 1). The spindle unit of the processing apparatus is composed of an air spindle that supports a spindle surrounded by a housing with high-pressure air. An injection port for injecting air to the spindle is provided on the inner wall of the housing, and a thrust bearing and a radial bearing are formed to rotatably support the spindle. A supply path connected to an injection port to supply air is formed inside the housing, and a supply port for connecting an air supply source to the supply path is formed on the outer wall of the housing. In such a spindle unit, when the supply of air from the supply port is interrupted, the air pressure for supporting the spindle drops sharply, and there is a problem that the spindle is bitten and damaged.

In order to solve such a problem, a configuration is known in which two air sources, a main air and a spare air, are connected to the processing apparatus. In such a configuration, when the air pressure of the main air drops, it is switched to spare air to protect the spindle from contacting the inner wall of the housing. Specifically, when switching between the main air and the spare air, the pressure switch connected to the main air switches to the spare air when the pressure switch reacts to the pressure drop, and when the pressure switch of the main air reacts to the pressure return, the spare air is switched to the main air. Switching to air. The main air and the spare air are merged on the upstream side from the vicinity of the inlet of the processing apparatus, and are supplied to the spindle unit from such an inlet through a single pipe communicating with the housing supply port of the spindle unit.

Japanese Unexamined Patent Publication No. 2011-83864

In the configuration in which air is supplied from the two air sources described above, if the pipe connecting the inlet of the device and the housing supply port is damaged near the housing, the pressure switch on the upstream side of the damaged position does not react. Therefore, there is a problem that the air source cannot be switched from the main air to the spare air so that the air supply to the injection port is not interrupted.

The present invention has been made in view of the above points, and one of the objects of the present invention is to provide a spindle unit capable of stabilizing the air supply by switching the air source.

The spindle unit of one aspect of the present invention includes a mount for mounting a processing tool, a spindle that rotates about the center of the mount, and a casing that surrounds the spindle, and is between the outer wall of the spindle and the inner wall of the casing. It is a spindle unit that circulates air and constitutes a radial air bearing and a thrust air bearing to rotatably support the spindle. The air can connect two air sources, the main air and the sub air, and the casing is the outer wall. A first supply port arranged on the outer wall and connected to the main air source, a second supply port arranged on the outer wall and connected to the sub air source, and a radial air bearing and a thrust air bearing arranged on the inner wall. The spout that ejects air, the first connection port, the second connection port, and the third connection port that branch in three directions to connect the first supply port, the second supply port, and the spout. A first pipe connecting the first supply port and the first connection port, a second pipe connecting the second supply port and the second connection port, and a spout A third pipe that connects the pipe and the third connection port, and a first check valve that is arranged in the first pipe and blocks the flow of air in the direction from the branch portion to the first supply port. , A second check valve, which is arranged in the second pipe and blocks the flow of air from the branch portion toward the second supply port, is provided, and the sub air source is based on the air pressure of the main air source. It is connected to two air sources, a main air source and a sub air source, with low air pressure, and the first check valve is opened by the pressure difference of the air supplied from the main air source with a pressure higher than that of the sub air source. Even if the second check valve is closed and the air supply from the main air source is cut off , the pressure in the first pipe and the third pipe is the second between the sub air source and the second check valve. The second check valve is opened when the pressure becomes lower than the pressure in the pipe of the pipe, and the air from the sub-air source can be instantly supplied so that the air bearing can be configured.

According to this configuration, the first supply port of the casing constituting the spindle unit is connected to the main air source, and the second supply port is connected to the sub air source. Then, when the air supply from the main air source is interrupted, the pressure drop is prevented by shutting off the air by the first check valve provided in the casing, and the second pipe, the second check valve and the branch are prevented. Air can be supplied from the sub-air source through the section. As a result, the two air sources can be mechanically switched in the spindle unit without using the control in the electric system by a pressure switch, a sensor, or the like. As a result, even if the piping connecting the inlet of the processing apparatus and the casing is damaged as in the conventional case, the air source can be switched from the main air to the sub air, and the air can be stably supplied. As a result, it is possible to prevent the spindle from being damaged due to the spindle coming into contact with the inner surface of the casing.

According to the present invention, the two air sources can be mechanically switched in the spindle unit, and the air supply can be stabilized by switching the air sources.

It is a perspective view of the grinding apparatus of this embodiment. It is sectional drawing of the spindle unit of this embodiment. It is a piping system diagram of the air switching means of this embodiment.

Hereinafter, the grinding apparatus of this embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the grinding apparatus of the present embodiment. In the following description, the grinding device is not limited to the device configuration dedicated to grinding as shown in FIG. 1, and for example, a series of machining such as grinding, polishing, and cleaning is fully automatically performed. It may be incorporated in a fully automatic type processing device.

As shown in FIG. 1, the grinding device 1 is configured to grind a wafer W on a chuck table 20 by using a small grinding wheel 44 in which a large number of grinding wheels 45 are arranged in an annular shape. The wafer W is carried into the grinding apparatus 1 with the protective tape T attached, and is held on the chuck table 20 via the protective tape T. The wafer W may be a plate-shaped member to be ground, a semiconductor wafer such as silicon or gallium arsenide, an optical device wafer such as ceramic, glass, or sapphire, or an as before device pattern formation. It may be a slice wafer.

A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 10 of the grinding device 1, and this opening is covered with a moving plate 11 movable together with the chuck table 20 and a bellows-shaped waterproof cover 12. ing. Below the waterproof cover 12, a ball screw type advancing / retreating means (not shown) for advancing / retreating the chuck table 20 in the X-axis direction is provided. The chuck table 20 is connected to a rotating means (not shown) and is configured to be rotatable by driving the rotating means. Further, on the upper surface of the chuck table 20, a holding surface 21 for sucking and holding the wafer W is formed by a multi-hole porous ceramic material.

The column 15 on the base 10 is provided with a grinding feed means 30 for grinding and feeding the grinding means 40 with respect to the holding surface 21 of the chuck table 20 in the Z-axis direction. The grinding feed means 30 has a pair of guide rails 31 arranged on the column 15 parallel to the Z-axis direction, and a motor-driven Z-axis table 32 slidably installed on the pair of guide rails 31. .. Nut portions (not shown) are formed on the back surface side of the Z-axis table 32, and a ball screw 33 is screwed into these nut portions. The ball screw 33 is rotationally driven by the drive motor 34 connected to one end of the ball screw 33, so that the grinding means 40 is moved along the guide rail 31 in the Z-axis direction.

The grinding means 40 is attached to the front surface of the Z-axis table 32 via the housing 41, and is configured to rotate the grinding wheel (processing tool) 44 around the central axis by the spindle unit 42. The spindle unit 42 is a so-called air spindle, and rotatably supports the spindle 55 (see FIG. 2) inside the casing 51 via high-pressure air. A mount 43 is connected to the tip of the spindle 55, and the spindle 55 rotates around the center of the mount 43. A grinding wheel 44 in which a large number of grinding wheels 45 are arranged in an annular shape is mounted on the mount 43. The grinding wheel 45 is formed by solidifying diamond abrasive grains with a binder such as a metal bond or a resin bond. In the grinding apparatus 1 of the present embodiment, the wafer W is thinned to a desired thickness by pressing the rotating grinding wheel 44 against the wafer W while supplying the grinding water.

Hereinafter, the spindle unit of the present embodiment will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the spindle unit of the present embodiment.

As shown in FIG. 2, the spindle unit 42 surrounds the spindle 55 in an upright posture with a casing 51, ejects air from the casing 51 to the outer surface of the spindle 55, and rotatably supports the spindle 55. It forms a bearing. A mount 43 equipped with a grinding wheel (processing tool) 44 is connected to the lower end (lower end) of the spindle 55, and a motor 71 of a rotation drive source is connected to the upper end side of the spindle 55. The motor 71 is composed of a rotor 72 provided at the upper end portion of the spindle 55 and a stator 74 provided on the inner peripheral surface of the casing 51 via a cooling jacket 73. A large number of cooling water passages 75 are formed in the cooling jacket 73, and heat generation of the motor 71 is suppressed by the cooling water passages 75.

Large-diameter discs 56 and 57 are formed at the lower end and the intermediate portion of the spindle 55, and an annular portion 52 is formed at the lower end of the casing 51 so as to enter between the discs 56 and 57. .. A slight gap is provided between the discs 56 and 57 of the spindle 55 and the annular portion 52 of the casing 51 to serve as an air passage. A large number of spouts 53 are arranged on the outer surface of the annular portion 52 which is the inner wall of the casing 51. Each spout 53 ejects high-pressure air supplied from the main air source 93 and the sub air source 94, which will be described later. The high-pressure air ejected from the ejection port 53 is circulated in a slight gap between the outer wall of the spindle 55 and the inner wall of the casing 51.

By ejecting high-pressure air from a large number of ejection ports 53 of the annular portion 52 to the outer surface of the spindle 55, the spindle 55 is float-supported with respect to the casing 51 via the high-pressure air. As a result, a radial air bearing and a thrust air bearing are formed in the casing 51, and the outer wall of the spindle 55 is rotatably supported by the radial air bearing and the thrust air bearing in the radial direction and the axial direction. At this time, since the disc portions 56 and 57 of the spindle 55 are floatingly supported by the thrust bearing in a wide range, the machining load acting on the spindle 55 in the thrust direction is appropriately dispersed.

The high-pressure air in the spindle 55 and the casing 51 is exhausted from above the spindle unit 42 while air-cooling the motor 71, and passes through the inside of the spindle cover 77 provided under the casing 51 from below the spindle unit 42. It is exhausted. A strip-shaped sponge material 78 for preventing the ingress of grinding water into the spindle cover 77 is attached to the lower inner surface of the spindle cover 77. The sponge material 78 narrows the gap between the spindle cover 77 and the spindle 55, and prevents the work waste from entering the spindle cover 77 during grinding without obstructing the exhaust of high-pressure air.

Further, the spindle 55 is formed so that a through-passage 58, which is a flow path for grinding water, penetrates the center of the spindle 55 in the vertical direction. The joint 62 of the casing 51 is provided with a nozzle 63 that protrudes downward, and the lower end of the nozzle 63 enters the gangway 58. The nozzle 63 is connected to a grinding water supply source (not shown), and the grinding water is supplied from the nozzle 63 through the gangway 58.

The flow paths 65 and 66 formed in the mount 43 and the grinding wheel 44 are communicated with the lower end of the through-passage 58, and the grinding water in the through-passage 58 is discharged to the outside from the drain port (discharging portion) 64 of the grinding wheel 44. To. In this way, the grinding water is supplied from the upper end side of the spindle 55 to the through-passage 58 by the nozzle 63, passes through the flow paths 65 and 66 of the mount 43 and the grinding wheel 44, and is below the spindle 55 by the drain port 64 of the grinding wheel 44. Grinding water is discharged from the side to the grinding wheel 45. During the grinding process, the grinding wheel 45 and the wafer W (see FIG. 1) are cooled by the grinding water, and the grinding debris is washed away from the upper surface of the wafer W together with the grinding water.

Here, the casing 51 of the present embodiment further includes an air switching means 80 as an inlet for air supplied to the ejection port 53. If the air switching means 80 is integrated as a configuration included in the casing 51, it may be a joint directly mounted on the casing 51, or a block-shaped housing may be provided to form a part of the casing 51. Can be exemplified. Hereinafter, the configuration of the air switching means 80 will be described with reference to FIG. FIG. 3 is a piping system diagram of the air switching means of the present embodiment.

As shown in FIG. 3, the air switching means 80 includes a first supply port 81, a second supply port 82, a branch portion 83 branching in three directions, a first pipe 84, a second pipe 85, and a third. The pipe 86, the first check valve 87, and the second check valve 88 are provided.

In the air switching means 80, the first supply port 81 and the second supply port 82 are arranged on the outer wall of the casing 51 so that the pipes can be connected on the outer surface side of the casing 51. The main air source 93 is connected to one end of the first supply port 81 via the first connection pipe 91, and the sub air source 94 is connected to one end of the second supply port 82 via the second connection pipe 92. It is connected. The main air source 93 and the sub air source 94 may be configured by a compressor or the like, and the pressure of the air supplied from them may be the same, or the main air source 93 may have a higher pressure than the sub air source 94. Further, the other end of the first supply port 81 is connected to the upstream end side of the first pipe 84, and the other end of the second supply port 82 is connected to the upstream end side of the second pipe 85.

The downstream end side of the first pipe 84 is connected to the first connection port 83a of the branch portion 83, and the downstream end side of the second pipe 85 is connected to the second connection port 83b of the branch portion 83. There is. Further, the upstream end side of the third pipe 86 is connected to the third connection port 83c of the branch portion 83. The downstream end side of the third pipe 86 is connected to the flow path 52a in the annular portion 52, and is connected to the ejection port 53 (see FIG. 2) through the flow path 52a. Therefore, the main air supplied through the first supply port 81 is ejected from the first connection port 83a of the first pipe 84 and the branch portion 83 through the third connection port 83c, the third pipe 86, and the flow path 52a. It is ejected from the exit 53. Further, the sub-air supplied through the second supply port 82 is discharged from the second connection port 83b of the second pipe 85 and the branch portion 83 via the third connection port 83c, the third pipe 86, and the flow path 52a. It is ejected from 53.

The first check valve 87 is arranged in the first pipe 84 and shuts off the flow of air in the direction from the branch portion 83 toward the first supply port 81. The second check valve 88 is arranged in the second pipe 85 and shuts off the flow of air from the branch portion 83 toward the second supply port 82. Therefore, in the first pipe 84 and the second pipe 85, even if the air pressure on the branch portion 83 side is higher than the air pressure on each supply port 81, 82 side, that is, the air sources 93, 94, each supply port 81 , It is regulated that air flows back to the 82 side.

Subsequently, the switching operation of the air supplied from the two air sources 93 and 94 will be described. Here, it is assumed that the supply pressures of the two air sources 93 and 94 are the same, and that the air supply from the main air source 93 is interrupted due to a malfunction of the main air source 93 or the first connecting pipe 91 during grinding. .. When the air supply from the main air source 93 is interrupted, the air pressure drops at the first supply port 81 and the first pipe 84 connected to the main air source 93 via the first connection pipe 91. On the other hand, since the supply of air from the sub air source 94 is continued and the inside of the casing 51 becomes high pressure as an air bearing, the second pipe 85 and the third pipe 86 are relative to the first pipe 84. It becomes high pressure. Therefore, air tries to flow from the second pipe 85 and the third pipe 86 toward the first pipe 84 through the branch portion 83, but the air flow is blocked by the first check valve 87. To. As a result, even if the air supply from the main air source 63 is interrupted, the air supply from the sub air source 94 is instantaneously continued without causing a drop in air pressure in the second pipe 85 and the third pipe 86. The air bearing can be configured.

When the air supply from the main air source 93 is restored from this state, the air in the first pipe 84 becomes high pressure, and the shutoff by the first check valve 87 is released. As a result, the air supply can be switched from the main air source 93 to the air supply through the first pipe 84, and the main air is supplied into the casing 51 so that the air bearing can be configured.

Even if the air supply from the sub-air source 94 is interrupted, the check valve that operates is changed from the first check valve 87 to the second check valve 88, except that the check valve that operates is changed from the first check valve 87 to the second check valve 88. Similarly, an air bearing can be configured.

As described above, in the spindle unit 42 of the present embodiment, even if the air pressure supplied from one of the air sources 93 and 94 decreases, the check valves 86 and 87 operate to operate the other air sources 93 and 94. It is possible to maintain the function of the air bearing by maintaining the air supply from. Therefore, the two air sources 93 and 94 can be mechanically switched by the configuration of the check valves 86 and 87 provided in the casing 51 without controlling by the electric system by a sensor or an electric device. As a result, even if a defect such as damage occurs in the connecting pipes 93 and 94, the air supply capable of functioning as an air spindle in the casing 51 can be stably continued. As a result, the air pressure between the spindle 55 and the casing 51 does not become less than the pressure at which the spindle 55 bites, and the spindle 55 can be prevented from being damaged.

In the above embodiment, the case where the main air and the sub air have the same pressure has been described, but these pressures may be different. For example, when the sub air has a lower pressure than the main air (for example, sub air 0.45 MPa, main air 0.5 MPa), the operating pressures of the check valves 87 and 88 are changed accordingly to the second check. The pressure of the valve 88 is lower than that of the first check valve 87.

Further, in the present embodiment, the spindle is formed so that the annular portion of the casing is inserted between the two discs, but the present invention is not limited to this configuration. The spindle and casing may be formed in any structure as long as the spindle can be rotatably supported.

Further, the embodiment of the present invention is not limited to the above-described embodiment and modification, and may be variously modified, replaced, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by the advancement of technology or another technology derived from it, it may be carried out by using that method. Therefore, the scope of claims covers all embodiments that may be included within the scope of the technical idea of the present invention.

Further, in the present embodiment, the configuration in which the present invention is applied to the spindle unit for the grinding device has been described, but for the spindle unit of another processing device capable of stabilizing the air supply by switching the air source. It is also possible to apply.

As described above, the present invention has an effect that the air supply can be stabilized by switching the air source, and is particularly useful for a spindle unit used in grinding.

42 Spindle unit 43 Mount 44 Grinding wheel (processing tool)
51 Casing 53 Spout 55 Spindle 81 First supply port 82 Second supply port 83 Branching part 83a First connection port 83b Second connection port 83c Third connection port 84 First piping 85 Second piping 86 Third piping 87 First check valve 88 Second check valve

Claims (1)

A mount for mounting a processing tool, a spindle that rotates around the center of the mount, and a casing that surrounds the spindle are provided, and air is circulated between the outer wall of the spindle and the inner wall of the casing to provide radial air. A spindle unit that constitutes a bearing and a thrust air bearing and rotatably supports the spindle.
The air makes it possible to connect two air sources, the main air and the sub air.
The casing is
A first supply port arranged on the outer wall and connectable to the main air source, a second supply port arranged on the outer wall and connected to the sub air source, and the radial air bearing arranged on the inner wall and the said A spout that ejects air to the thrust air bearing, and a first connection port and a second connection that branch in three directions to connect the first supply port, the second supply port, and the spout. A branch portion having a port and a third connection port, a first pipe connecting the first supply port and the first connection port, and the second supply port and the second connection port. A second pipe connecting the above, a third pipe connecting the spout and the third connection port, and a third pipe connecting the spout and the third connection port, arranged in the first pipe, and from the branch portion to the first supply port. A first check valve that shuts off the flow of air in the direction toward the direction and a second check valve that is arranged in the second pipe and blocks the flow of air in the direction from the branch portion toward the second supply port. With a check valve,
The sub air source has an air pressure lower than that of the main air source.
Connected to two air sources, the main air source and the sub air source,
The pressure difference of the air supplied from the main air source at a pressure higher than that of the sub air source opened the first check valve and closed the second check valve, and the air supply from the main air source was cut off. Even so , the pressure in the first pipe and in the third pipe becomes lower than the pressure in the second pipe between the sub-air source and the second check valve, so that the second pipe is used. check valve is opened, spindle unit that allows configuration of the air bearing and allows the supply air from the sub air source instantaneously.

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