Motor spindle

Abstract

To provide a motor spindle which achieves reduction of a load acting on a bearing.SOLUTION: In order to achieve the above object, a motor spindle includes a coolant supply part and further includes: a case; a spindle supported by a bearing; a motor which rotates the spindle; a drill; and a collet chuck and a chuck nut which fix the drill to the spindle. The spindle is formed with a coolant chamber in which a coolant flows. The chuck nut is formed with a coolant introduction port for introducing the coolant. The drill includes a blade which cuts an object to be processed, is formed with an internal passage through which the coolant flows, and may supply the coolant to the internal passage to supply the coolant to a blade portion. The coolant introduction port and the internal passage of the coolant chamber communicate with each other, and the coolant supply part may be configured to supply the coolant to the coolant introduction port.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor spindle that supplies a coolant, such as cutting oil, to a cutting position via the inside of a drill. [Background technology]

[0002] Conventionally, there is a motor spindle (also called a spindle motor) equipped with a coolant supply structure that supplies coolant to a cutting position through the inside of a drill. For example, Patent Document 1 discloses a motor spindle as a drill unit (Patent Document 1).

[0003] With a drill attached to the spindle, this type of motor spindle draws cutting oil into an oil hole formed inside the spindle from the rear end via a rotary joint, flows the cutting oil from the oil hole in the spindle to the oil hole in the drill, and then discharges it from the tip of the drill, supplying the cutting oil to the cutting position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-239436 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the motor spindle described in Patent Document 1 is designed to take in cutting oil into an oil hole formed inside the spindle in the thrust direction from the rear end of the spindle via a rotary joint, so that thrust pressure acts on the spindle when the cutting oil is poured into the spindle. This causes a problem in that a load in the thrust direction acts on the bearing that rotatably supports the spindle. In particular, the smaller the outer diameter of the bearing, the more susceptible it is to the effects of this thrust load, and the smaller the motor spindle, the more difficult it becomes to adopt the cutting oil supply structure described in Patent Document 1.

[0006] The present invention is devised to solve the above-mentioned problems, and aims to provide a spindle motor in which cutting oil passes through the inside of a drill and is supplied to the cutting position from the tip, in which the thrust load acting on the spindle when cutting oil is taken into the spindle. [Means for solving the problem]

[0007] In order to solve the problem, in a motor spindle equipped with a coolant supply unit, the motor spindle includes a case that forms an outer shell, a spindle rotatably supported by bearings, a motor that rotates the spindle, a drill that cuts the workpiece, and a collet chuck and chuck nut that fix the drill to the spindle, the spindle is formed with a coolant chamber through which coolant supplied from the outside flows, the chuck nut is formed with a coolant inlet for introducing coolant into the interior, the drill is equipped with a blade at its tip that cuts the workpiece and has an internal flow path through which coolant flows, coolant can be supplied to the blade portion by supplying coolant to the internal flow path, the coolant inlet, the coolant chamber and the internal flow path are connected, and the coolant supply unit is configured to supply coolant to the coolant inlet. Effect of the Invention

[0008] According to the present invention, in a motor spindle that supplies cutting oil to a cutting position from the tip through the inside of a drill, it is possible to reduce the thrust load acting on the spindle when the cutting oil is taken into the spindle. [Brief description of the drawings]

[0009] [Figure 1] Perspective view of a motor spindle with a coolant supply [Diagram 2] (a) Front view of the motor spindle equipped with the coolant supply unit. (b) Left side view of the motor spindle equipped with the coolant supply unit. [Diagram 3] (a) Exploded view of a motor spindle equipped with the coolant supply unit shown in Figure 2(b). (b) Cross-sectional view of (a) (The cross-sectional view shows the state of the motor spindle cut at the center from the left to right and viewed from the left side). [Figure 4] Exploded perspective view of the motor spindle [Diagram 5] Cross section along the line AA shown in FIG. 2(a) [Figure 6] Enlarged view of the collet chuck position in Figure 5 [Figure 7] Cross section along the line B-B shown in Figure 2(b) [Figure 8] (a) Left side view of the collet chuck (b) Perspective view of the collet chuck (c) CC cross section shown in (b) (CC cross section is cut at a position passing through the left-right center of the collet chuck and viewed from the left side) [Figure 9] (a) Left side view of the chuck nut (b) Perspective view of the chuck nut (c) DD cross section shown in (b) (DD cross section is cut at a position passing through the left-right center of the chuck nut and viewed from the left side) [Figure 10] (a) Left side view of the coolant guide (b) Perspective view of the coolant guide (c) E-E cross section shown in (b) (the E-E cross section is cut at a position passing through the left-right center of the coolant guide and viewed from the left side) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment) Hereinafter, an embodiment will be described with reference to Figs. 1 to 10. In this embodiment, the axial direction and radial direction of the motor spindle 100 are defined based on the rotation axis of the spindle 120. In other words, the axial direction is a direction parallel to the rotation axis of the spindle 120. The radial direction is a direction perpendicular to the rotation axis. In addition, in the motor spindle 100, the side where the drill 150 is located is the front, and the side where the motor 140 is located is the rear. Furthermore, the up-down and left-right directions are based on the state where the motor spindle 100 is viewed from the rear. For reference, the up-down and left-right directions are shown in Figs. 1 and 2.

[0011] 1 to 3, a motor spindle 100 is attached to a machine tool and operated to perform cutting such as drilling holes in a workpiece, and is provided with a coolant supply unit 200 that supplies coolant to the motor spindle 100. The motor spindle 100 and the coolant supply unit 200 are collectively referred to as a cutting tool S. 4 to 6, the motor spindle 100 includes a case 110, a spindle 120, a bearing 130, a motor 140, a drill 150, a collet chuck 160, and a chuck nut 170. The case 110 includes a spindle 120, a bearing 130, a motor 140, a drill 150, a collet chuck 160, and a chuck nut 170.

[0012] The case 110 forms the outer shell of the motor spindle 100, and is a cylindrical member made of metal such as stainless steel. In addition, a protrusion 111 that protrudes in the radial direction is formed on the outer circumferential surface of the case 110. The motor 140 is a driving source that rotates the spindle 120 , and is located inside the case 110 . The motor 140 includes a rotor 141 and a stator 142 .

[0013] The spindle 120 is a shaft-shaped member that is long in the direction of the rotation axis. The spindle 120 is rotatably supported by bearings 130 inside the case 110 with a forward-facing opening 121 facing the outside of the case 110. The spindle 120 includes a chuck holding portion 122. The chuck holding portion 122 is a portion that receives and holds the collet chuck 160 from the opening 121. The chuck holding portion 122 is a tapered portion that is wider as it approaches the opening 121 and narrows as it approaches the rear end. In other words, the chuck holding portion 122 is a tapered portion that widens toward the front.

[0014] A coolant chamber 123 through which coolant (cutting oil) supplied from the outside of the motor spindle 100 flows is provided inside the spindle 120 and behind the chuck holding portion 122. The coolant chamber 123 is a space inside the spindle 120 that extends from the rear side of the chuck holding portion 122 to a position in front of the motor 140. The coolant chamber 123 and the chuck holder 122 are adjacent to each other in the front-rear direction. That is, the space surrounded by the chuck holder 122 is connected to the front-rear direction of the coolant chamber 123. In addition, a bearing 130 (front bearing 131) is located in the radial direction of the coolant chamber 123.

[0015] Next, a male screw 124 is formed on the outer peripheral surface of the spindle 120 from the opening side 121. This male screw 124 is used to screw the chuck nut 170 to the spindle 120 by screwing the female screw 172 of the chuck nut 170 into it. Furthermore, a rotor 141 is provided on the outer periphery of the spindle 120 at a position rearward of the coolant chamber 123. A stator 142 is located radially outward of the rotor 141 and inside the case 110. The rotor 141 and the stator 142 face each other with a gap therebetween, constituting a motor 140.

[0016] The bearings 130 include a front bearing 131 that supports the spindle 120 on the front side of the case 110, and a rear bearing 132 that supports the spindle 120 on the rear side of the case 110. The front bearing 131 is located in the radial direction of the coolant chamber 123 of the spindle 120. The rear bearing 132 is located behind the motor 140.

[0017] The drill 150 is attached to the motor spindle 100 and rotates to cut an object to be processed. The drill 150 has an internal flow passage 151 through which a coolant flows, which communicates from the rear end to the tip. The rear end side of the internal flow passage 151 opens toward the coolant chamber 123, and the front end side opens toward the front direction. A blade 152 that cuts the object to be processed is located at the tip of the drill 150. By supplying coolant from the rear end of the drill 150 to the internal flow passage 151, it is possible to supply coolant to the portion of the blade 152 that is the cutting position.

[0018] Collet chuck 160 clamps drill 150 to fix drill 150 to motor spindle 100. Referring to Fig. 8, collet chuck 160 has a cylindrical body 161. Body 161 has a holding opening 162 penetrating the interior in the axial direction, a slot 164 communicating with an outer circumferential surface 163 to holding opening 162 and extending in the axial direction, a nut receiving surface 165 formed on the front surface of body 161, and a held portion 166 formed to have a tapered shape with an outer diameter that becomes smaller toward the rear end of body 161.

[0019] The holding opening 162 is a portion through which the drill 150 is passed and held by being pinched from the radial direction. The slots 164 are gaps that facilitate deformation of the collet chuck 160 in the direction of holding the drill 150 when the collet chuck 160 is pressed by the chuck nut 170 when the chuck nut 170 is tightened onto the spindle 120. A plurality of slots 164 are formed, and the gaps of the slots 164 communicate from the outer circumferential surface 163 of the collet chuck 160 to the rear end. The nut receiving surface 165 is a surface that comes into axial contact with the chuck nut 170 when the chuck nut 170 is tightened onto the spindle 120. In particular, the nut receiving surface 165 is configured to have an inclined surface that tapers forward, so that the axial force received from the chuck nut 170 is directed radially inward.

[0020] The held portion 166 is a portion that is held by the chuck holding portion 122 when the collet chuck 160 is attached to the spindle 120 . The held portion 166 has a tapered shape formed so that the outer diameter becomes smaller toward the rear end of the body portion 161. The held portion 166 is held by being inserted from the front side into the chuck holding portion 122, which is wider as it is closer to the opening 121 and narrows toward the rear end.

[0021] The chuck nut 170 presses the collet chuck 160 during the process of screwing it onto the spindle 120 , thereby fixing the drill 150 to the spindle 120 . 9, the chuck nut 170 is a cylindrical member having a drilled opening 171 penetrating in the axial direction at the position that serves as the center of rotation. A female screw 172 is formed on the inner wall of the chuck nut 170 from the rear end side.

[0022] Further, a nut side tapered portion 173 is formed on the opening edge of the drill opening 171 inside the chuck nut 170 so as to surround the drill opening 171. The nut side tapered portion 173 has a shape that widens radially outward toward the rear side. In other words, the nut side tapered portion 173 has a shape that widens toward the rear. The nut side tapered portion 173 is a portion that comes into contact with the nut receiving surface 165 of the collet chuck 160 in the axial direction when the chuck nut 170 is screwed onto the spindle 120 .

[0023] Furthermore, the chuck nut 170 is formed with a coolant inlet 174 that penetrates from the outside to the inside in the radial direction. This coolant inlet 174 is an opening that introduces coolant from the outside to the inside of the chuck nut 170. A plurality of coolant inlets 174 are formed, and these are lined up in the rotation direction of the spindle 120 so as to surround the rotation axis of the spindle 120. In this embodiment, two coolant inlets 174 are provided.

[0024] The motor spindle 100 configured in this manner secures the drill 150 as follows. 4 to 6, in a state in which held portion 166 of collet chuck 160 is held by chuck holding portion 122, drill 150 is inserted into holding opening 162. The collet chuck 160 and the chuck nut 170 are assembled together with the drill 150 passing through the drill opening 171. Then, the female screw 172 of the chuck nut 170 is screwed into the male screw 124 of the spindle 120, whereby the chuck nut 170 is fixed to the spindle 120 by screwing.

[0025] In the process of screwing the chuck nut 170 to the spindle 120, the nut side tapered portion 173 of the chuck nut 170 comes into contact with and presses against the nut receiving surface 165 of the collet chuck 160 in the axial direction. At this time, because nut receiving surface 165 is an inclined surface narrowing toward the front, the axial force received from nut side tapered portion 173 is redirected radially inward, and collet chuck 160 deforms so as to hold drill 150. Due to this action, collet chuck 160 grips and fixes drill 150 from the radial direction.

[0026] When the drill 150 is fixed to the spindle 120, the coolant inlet port 174, the gap in the slot 164, and the coolant chamber 123 are in communication with each other. In other words, the coolant can enter the inside of the chuck nut 170 from the coolant inlet port 174, pass through the gap in the slot 164, pass through the collet chuck 160, and flow into the inside of the coolant chamber 123.

[0027] Next, the coolant supply unit 200 will be described with reference to FIGS. 1 to 3 and 5. FIG. The coolant supply unit 200 is a portion that supplies coolant to the motor spindle 100. The coolant supply unit 200 includes a holder 210, a connection pipe 220, and a coolant guide 230. The holder 210 is for fixing each part of the coolant supply unit 200, such as the coolant guide 230 and the connection pipe 220. The holder 210 is a part that is connected to the motor spindle 100. The holder 210 has a generally rectangular parallelepiped shape and includes a connection portion 211 where the motor spindle 100 and a coolant guide 230 are provided, and a coolant flow path 215 that connects to a connection pipe 220 and guides the coolant toward the spindle 120 .

[0028] The connection part 211 is an internal space that penetrates the holder 210 in the front-rear direction and is open in the front-rear direction. A front opening 217 opens at the front side of the connection part 211, and a rear opening 218 opens at the rear side. The connection part 211 in this embodiment is generally cylindrical. A coolant flow path 215 opens within the connection part 211, and the internal space of the connection part 211 and the coolant flow path 215 communicate with each other.

[0029] An inwardly protruding step 212 is formed inside the connection portion 211. Furthermore, an excess coolant discharge passage 213 that communicates from the inside of the connection portion 211 to the outside of the holder 210 is formed. The surplus coolant discharge path 213 is a coolant flow path for discharging a portion of the coolant supplied toward the spindle 120 that does not flow into the inside of the spindle 120 to the outside of the holder 210. Therefore, one end of the surplus coolant discharge path 213 opens toward the inside of the connection part 211, and the other end opens toward the outside of the holder 210. One end of the connection pipe 220 is connected to the coolant passage 215, and the other end is connected to an external coolant passage 300 such as a hose leading to a coolant supply source.

[0030] Next, the coolant guide 230 will be described with reference to FIGS. The coolant guide 230 is a portion that guides the coolant flowing from inside the holder 210 to the coolant inlet 174 of the chuck nut 170 that rotates together with the spindle 120 . The coolant guide 230 is configured with various parts on a cylindrical body 231 that is open in the front-rear direction. An outer groove 232 is formed on an outer periphery 235 of the body 231 so as to go around the outer periphery. The opening of the outer groove 232 faces outward in the radial direction. In other words, the opening of the outer groove 232 faces in the opposite direction to the rotation center of the spindle 120.

[0031] An inner groove 233 is formed around the inner peripheral surface of the inner circumferential portion of the cylindrical body 231. The opening of the inner groove 233 faces inward in the radial direction. In other words, the opening of the inner groove 233 faces the direction of the rotation center of the spindle 120. Further, in the cylindrical body 231, a communication opening 234 is formed which connects the internal space of the inner groove 233 and the internal space of the outer groove 232. A plurality of these communication openings 234 are formed at appropriate intervals in the circumferential direction of the cylindrical body 231. In the case of the present embodiment, four communication openings 234 are formed. These noren openings are provided at equal distances from each other.

[0032] The coolant guide 230 configured in this manner is attached to the holder 210 so as to close the front opening 217 of the connection part 211 of the holder 210, with the two openings of the cylinder 231 facing the front and rear directions, respectively. In other words, the coolant guide 230 is attached and fixed to the front opening side 217 of the connection part 211. When the coolant guide 230 is attached to the holder 210 , the coolant flow passage 215 is positioned in the direction of the opening of the outer recessed groove 232 .

[0033] Then, by attaching the coolant guide 230 to the holder 210, a space surrounded by the outer groove 232 and the inner wall of the connection part 211 is formed. This space is the coolant distribution chamber 240. The coolant distribution chamber 240 is in communication with the coolant flow path 215 since the coolant flow path 215 is located in the opening direction of the outer groove 234. In other words, the coolant distribution chamber 240 is a space into which the coolant that has flowed through the coolant passage 215 flows on its way toward the spindle 120. The coolant distribution chamber 240 is a ring-shaped space positioned so as to surround the outside of the inner groove 233.

[0034] Next, the internal space of the inner groove 233 becomes a coolant supply chamber 250, which is a space just before coolant is poured into the spindle 120. Also, since a communication opening 234 is formed to connect the internal space of the inner groove 233 and the internal space of the outer groove 234, the coolant supply chamber 250, which is the internal space of the inner groove 233, and the coolant distribution chamber 240, which is the internal space of the outer groove 234, are partitioned by the outer circumferential portion 235 and are connected by the communication opening 234. Therefore, the coolant that has flowed through the coolant flow passage 215 flows into the coolant supply chamber 250 and then flows into the coolant distribution chamber 240 through the communication opening 234 .

[0035] The above-described coolant supply unit 200 and the motor spindle 100 are connected as follows. 3 and 5 to 7, the motor spindle 100 is inserted into the rear opening 218 of the holder 210 from the drill 150 side, and reaches the inside of the connection part 211. The position of the motor spindle 100 relative to the coolant supply part 200 is determined when the protruding part 111 of the motor spindle 100 abuts against the step 212 of the holder 210 from behind. In this state, a fixing screw 260 is screwed from behind into a screw formed on the inside of the rear opening 218. The fixing screw 260 is ring-shaped, and a screw groove is formed on the outer periphery of the ring. With the fixing screw 260 screwed into the rear opening 218, the motor spindle 100 is passed through the inner opening of the ring, and the protrusion 111 is sandwiched between the fixing screw 260 and the step 212, thereby fixing the motor spindle 100 to the holder 210. In other words, the motor spindle 100 is fixed to the coolant supply part 200.

[0036] When the coolant supply unit 200 and the motor spindle 100 are connected, the chuck nut 170 is positioned so as to penetrate in the front-rear direction through the opening of the coolant guide 230. In this state, a gap is formed between the chuck nut 170 and the coolant guide 230 such that the rotation of the chuck nut 170, which rotates together with the spindle 120, is not impeded.

[0037] Further, an opening of the inner groove 233 of the coolant guide 230 is positioned radially of the chuck nut 170. In other words, a coolant supply chamber 250 is positioned radially of the chuck nut 170 so as to surround the periphery of the chuck nut 170. Therefore, the coolant supply chamber 250 and the coolant inlet 174 are positioned opposite each other in the radial direction. In other words, the coolant supply chamber 250 and the coolant inlet 174 are in communication with each other.

[0038] Further, the front end 175 of the chuck nut 170 protrudes from the front opening 217 to the outside of the holder 210. The front end 175 is configured so that a tightening tool such as a wrench can be applied to it. Since the front end 175 protrudes to the outside from the holder 210 in this manner, a tightening tool can be applied to the chuck nut 170 when the chuck nut 170 is screwed and fixed to the spindle 120. Further, the front portion of the drill 150 held by the collet chuck 160 , including the cutting edge 152 , protrudes forward from the holder 210 .

[0039] Although the motor spindle 100 holding the drill 150 has been described as being attached to the coolant supply unit 200, the chuck nut 170 can be loosened from the spindle 120 with the motor spindle 100 and the coolant supply unit 200 connected. Therefore, with the motor spindle 100 and the coolant supply unit 200 connected, only the drill 150 can be attached or detached.

[0040] As described above, the coolant supply unit 200 and the motor spindle 100 are connected, and therefore operate as follows when cutting an object to be cut. In each drawing, the flow F of the supplied coolant is indicated by a dotted arrow line. The motor spindle 100 is rotated by the motor 140 using power supplied from the attached machine tool. This rotates the spindle 120, enabling the drill 150 to cut the workpiece. Note that the coolant supply unit 200 is fixed to the case 110, and therefore does not move relative to the case 110 when the spindle 120 rotates.

[0041] Moreover, when the motor 140 is rotating, coolant is supplied from a supply source such as an attached machine tool to the coolant supply unit 200. The coolant is supplied at increased pressure so that it flows into the inside of the spindle 120. Regarding the coolant supply pressure, taking an example of a motor spindle with certain specifications, if the diameter is 30 to 50 mm and the operating rotation speed is 20,000 to 30,000 revolutions per minute, the coolant supply pressure is about 15 to 30 MPa. Although this value will vary depending on the motor spindle specifications, the properties of the coolant, and the conditions of use, the smaller the motor spindle diameter and the higher the rotation speed used, the higher the pressure at which the coolant needs to be supplied.

[0042] 5 to 7, the supplied coolant flows from an external coolant flow passage 300 connected to a supply source into a connecting pipe 220, and passes through a coolant flow passage 215 to reach a coolant distribution chamber 240. The coolant that flows into the coolant distribution chamber 240 fills the inside of the ring-shaped coolant distribution chamber 240. The coolant distribution chamber 240 is a coolant flow path that distributes the pressure and amount of the coolant flowing inside the coolant supply chamber 250 so that the pressure and amount are uniform throughout.

[0043] Next, the coolant in the coolant distribution chamber 240 flows through the communication opening 234 into the coolant supply chamber 250. Here, the coolant supply chamber 250 is ring-shaped and is surrounded by the ring-shaped coolant distribution chamber 240. The coolant supply chamber 250 and the coolant distribution chamber 240 are connected by a plurality of communication openings 234 arranged at appropriate intervals. Therefore, the coolant inside the coolant distribution chamber 240 flows into the coolant supply chamber 250 through any one of the multiple communication openings 234 .

[0044] Next, since the coolant supply chamber 250 is ring-shaped, it surrounds the periphery of the chuck nut 170 which rotates together with the spindle 120. In other words, a plurality of coolant introduction ports 174 provided in the chuck nut 170 are open toward the coolant supply chamber 250. Then, the coolant inside the coolant supply chamber 250 flows into the inside of the rotating chuck nut 170 from the coolant inlet 174. The coolant that has entered the inside of the chuck nut 170 flows into the inside of the slot 164 of the collet chuck 160 and flows into the coolant chamber 123. In this way, the coolant inside the coolant supply chamber 250 flows into the inside of the spindle 120.

[0045] The coolant inside the coolant chamber 123 flows from the rear end of the drill 150 held in the collet chuck into the internal flow passage 151 inside the drill 150, flows forward, and is ejected to the outside of the drill 150 from the front opening of the internal flow passage 151 located near the cutting edge 152. Furthermore, any coolant that does not fit into the coolant inlet 174 and overflows flows out of the coolant supply chamber 250 through the gap between the coolant guide 230 and the chuck nut 170 and is discharged to the outside of the coolant supply section 200 through the discharge passage 213 or is discharged to the front side of the coolant supply section 200.

[0046] As described above, in the motor spindle 100 equipped with the coolant supply unit 200, the coolant inlet 174 is provided in the chuck nut 170, and a coolant intake flow path is formed that runs from the coolant inlet 174 through the slot 164 of the collet chuck 160 to the coolant chamber 123 inside the spindle. The coolant supply unit 200 supplies coolant to the coolant inlet 174.

[0047] This allows the coolant to be supplied radially into the inside of the spindle 120, reducing the axial pressure when the coolant is supplied, thereby reducing the axial load acting on the bearing 130. In particular, this effect makes it possible to supply coolant at higher pressure to the spindle 120, thereby enabling coolant to be efficiently supplied to the smaller motor spindle 100. In addition, because it is possible to supply coolant at higher pressure, the amount of coolant supplied can be increased, and it becomes possible to rotate and drive the motor spindle 100 at a higher speed.

[0048] In addition, the coolant inlet 174 of the chuck nut 170, which is the coolant inlet on the motor spindle side, is surrounded by a ring-shaped coolant supply chamber 250, and the coolant is filled around the chuck nut 170 to increase the coolant pressure, causing the coolant to flow into the inside of the coolant inlet 174. This causes the coolant to fill the area around the chuck nut 170, which is attached to the spindle 120 and rotates together with the spindle 120, thereby providing the effect of a fluid bearing in which the coolant supports the rotating chuck nut 170 from the radial direction.

[0049] In particular, the coolant supply chamber 250 communicates with the coolant distribution chamber 240 through the communication opening 234, but is separated from the coolant distribution chamber 240 by the outer circumferential portion 235, so that the coolant supply chamber 250 and the coolant distribution chamber 240 are configured as independent regions. In other words, because the coolant supply chamber 250 is an independent area, the pressure of the coolant capable of holding the rotating chuck nut 170 from the radial direction can be increased, and the effect of the fluid bearing can be more effectively achieved. In addition, the position where the fluid bearing effect occurs is around the chuck nut 170, which is close to the workpiece during operation. This has the effect of suppressing wobble of the rotation axis of the spindle due to the load when cutting the workpiece.

[0050] In addition, since the coolant supply unit 200 and the motor spindle 100 are fixed and connected by screws, even if coolant supplied at high pressure flows into the coolant supply unit 200, the coolant supply unit 200 can be maintained in a stable state without moving relative to the motor spindle 100. Furthermore, since the coolant chamber 123 in the spindle 120 is located radially inside the bearing 130, the heat generated in the bearing 130 can be cooled by the coolant. [Explanation of symbols]

[0051] 100 Motor Spindle 110 cases 111 Protrusion 120 Spindle 121 Aperture 122 Chuck holder 123 Coolant Room 124 Male screw 130 Bearing 131 Front bearing 132 Rear bearing 140 Motor 141 Rotor 142 Stator 150 Drill 151 Internal flow path 152 blades 160 Collet Chuck 161 Torso 162 Retention aperture 163 Outer surface 164 Slit 165 Nut receiving surface 166 Holding part 170 Chuck Nut 171 Drilling 172 Female screw 173 Nut side taper 174 Coolant inlet 175 Front end 200 Coolant supply unit 210 Holder 211 Connection 212 steps 213 Coolant drain 215 Coolant passage 217 Front opening 218 Posterior opening 220 Connecting Pipe 230 Coolant Guide 231 Cylinder 232 Outer groove 233 Inner groove 234 Communication opening 235 Outer periphery 240 Coolant Distribution Room 250 Coolant supply room 260 Fixing screw 300 External coolant flow passage F Coolant flow

Claims

1. In a motor spindle equipped with a coolant supply unit, The motor spindle includes a case that forms an outer shell, a spindle that is rotatably supported by a bearing, a motor that rotates the spindle, a drill that cuts an object to be processed, and a collet chuck and a chuck nut that fix the drill to the spindle, A coolant chamber is formed in the spindle, through which coolant supplied from the outside flows, The chuck nut is formed with a coolant inlet for introducing coolant into the inside thereof, The drill has a blade at a tip for cutting an object to be processed, and an internal flow passage through which a coolant flows is formed, and the coolant can be supplied to the blade by supplying the coolant to the internal flow passage, the coolant inlet, the coolant chamber, and the internal flow passage are in communication with each other, The motor spindle, wherein the coolant supply unit supplies coolant to the coolant inlet.

2. 2. The motor spindle according to claim 1, wherein the coolant supply unit includes a holder, and the motor spindle is fixed to the holder, thereby fixing the coolant supply unit and the motor spindle.

3. 2. The motor spindle according to claim 1, wherein the coolant supply unit includes a coolant guide that guides the coolant flowing from the coolant supply unit to the coolant inlet port of the chuck nut that rotates together with the spindle.

4. 4. The motor spindle according to claim 3, wherein the coolant guide includes a coolant supply chamber surrounding the periphery of the chuck nut which rotates together with the spindle.

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