Tool seating confirmation device

Abstract

Provided is a tool seating confirmation device that accurately confirms the mounted state of a tool, the tool seating confirmation device including: an air flow passage formed across a seating surface of a rotating spindle on which a tool from a housing of a tool main shaft device is mounted; an air supply source that supplies air to the air flow passage; an opening / closing valve connected to the air flow passage; a pressure sensor connected to the air flow passage; and a flow passage coupler that is formed on the housing side and in which a spool, which has a flow passage formed in a center section thereof and is displaced due to air pressure, connects a primary side flow passage provided on the housing side and a secondary flow passage formed in the spindle within the air flow passage, the flow passage coupler having formed therein a breather hole that is able to let air in and out of a space in which is built a spring that urges the spool against the air pressure.

Description

[Technical Field]

[0001] The present invention relates to a tool seating confirmation device for determining whether a tool is correctly attached to a tool spindle device when the tool is attached to the tool spindle device. [Background technology]

[0002] Some machine tools have an automatic tool changer (ATC) and are configured to automatically load and unload tools onto and from a tool spindle unit. In this case, a tool seating confirmation device is configured on the tool spindle unit to automatically determine whether the tool is properly loaded. Patent Document 1 below also discloses a conventional example of a tool seating confirmation device. A tool spindle unit is designed so that a tool held in a tool holder can be loaded onto a main spindle (spindle) rotatably supported by bearings. A port is formed on the seating surface of the device body where the tool holder abuts, forming an air passage for supplying air. A spool with a passage penetrating through its center is inserted midway through the air passage and is biased by a spring from the secondary side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-259906 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional tool seating confirmation device, when a tool holder is seated in the tapered hole of the spindle due to the installation of a tool, the spool is pressurized and displaced by the supplied air, closing the gap between the spindle and the housing, causing the internal pressure in the flow path to rise, activating the operating switch and confirming the seating. However, the conventional tool seating confirmation device is unable to stabilize the state in which the spool closes the gap with the supplied air, making it difficult to accurately confirm the seating using the operating switch. This is thought to be because the spool is incorporated into the housing in a relatively airtight state, reducing the pressure difference between the flow path side and the contracting spring space, making it impossible for the supplied air to suppress the biasing force of the spring.

[0005] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a tool seating confirmation device that can accurately confirm the state in which a tool is attached. [Means for solving the problem]

[0006] A tool seating confirmation device according to one aspect of the present invention includes an air flow path formed from a housing of a tool spindle device to a seating surface of a spindle that rotates with a tool attached thereto, an air supply source that supplies air to the air flow path, an on-off valve connected to the air flow path, a pressure sensor connected to the air flow path, and a primary air flow path formed in the housing and a secondary air flow path formed in the spindle, the primary air flow path being provided on the housing side. In the recess formed at the end of A spool with a flow path in the center that is displaced by air pressure The tip of the and a flow path connector that connects the spool and has a breathing hole formed therein that allows air to enter and exit the space in which a spring that biases the spool against air pressure is incorporated. [Effects of the Invention]

[0007] According to the above configuration, when a tool is attached to the tool spindle device, the on-off valve is opened and air is supplied from the air supply source to the air flow path formed from the housing to the seating surface of the spindle. Air flows from the primary flow path into the flow path coupler, and the air pressure displaces the spool against the biasing force of the spring, causing air to flow to the secondary flow path through a flow path that crosses the gap between the housing and the spindle. If the opening formed on the seating surface is blocked by the tool, the internal pressure of the air flow path increases, activating the pressure sensor. At this time, the spool, which is displaced by air pressure, stabilizes as air in the space where the spring is installed is released through the breathing hole, allowing accurate confirmation of the tool attachment state. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a tool spindle unit equipped with a tool seating confirmation device. [Figure 2] 2 is an enlarged partial cross-sectional view of the tool spindle device shown in FIG. 1, illustrating an embodiment of a tool seating confirmation device. FIG. [Figure 3] 3 is an enlarged cross-sectional view of a flow path connector constituting the tool seating confirmation device in a normal state shown in FIG. 2. FIG. [Figure 4] 3 is an enlarged cross-sectional view of a flow path connector constituting the tool seating confirmation device in FIG. 2 in a state where tool seating is confirmed. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a tool seating confirmation device according to the present invention will be described below with reference to the drawings. Fig. 1 is a cross-sectional view showing a tool spindle device equipped with a tool seating confirmation device according to this embodiment. In the tool spindle device 1, a cylindrical spindle 3 serving as the main spindle is rotatably mounted in a housing 4 by bearings 11 and 12. The rotation of the rotatable spindle 3 can be controlled by a spindle motor 5 provided within the housing 4. A tool 80 can be attached and detached to the tip of the spindle 3, as indicated by the dashed line.

[0010] A cylindrical seating member 13 is fitted into and screwed to the tip of the hollow spindle 3. A tool 80 is inserted into the seating member 13 at the connecting portion of a tool holder 81 formed integrally with the spindle 3. A draw bar 6 is inserted into the center of the spindle 3, and a tool holding portion 15 is formed at the tip of the draw bar 6, which engages with the tool holder 81 and holds it so as to retract it. Therefore, when rotation is imparted to the spindle 3 by the spindle motor 5, the connected tool holder 81 and the tool 80 rotate, and machining of the workpiece is performed.

[0011] The tool 80 must be accurately mounted on the tool spindle unit 1. For this reason, the tool spindle unit 1 is provided with a tool seating confirmation device for confirming that the tool holder 81 is accurately seated on the seating member 13. Fig. 2 is an enlarged view of a cross section of part A of the tool spindle unit 1 shown in Fig. 1, showing the tool seating confirmation device of this embodiment. Figs. 3 and 4 are enlarged cross-sectional views of Fig. 2 showing the flow path coupler that constitutes the tool seating confirmation device, with Fig. 3 showing the normal state and Fig. 4 showing the state during tool seating confirmation.

[0012] When a tool 80 is attached to the tool spindle device 1, the tool seating confirmation device 10 confirms whether or not a flange portion 811 of the tool holder 81 is properly in contact with a seating surface 131 of the seating member 13. Air pressure is used for the seating confirmation, and air is supplied to a discharge flow path 28 that opens to the seating surface 131. A primary flow path 25 is formed in the housing 4, and the primary flow path 25 is connected via an electromagnetic on-off valve 23 to a supply flow path 22 that is connected to an air supply source 21 such as a compressor. The primary flow path 25 is provided with a pressure switch 24 that is activated when the internal pressure rises to a threshold value and transmits a detection signal to a control device (not shown).

[0013] The spindle 3 is formed with a secondary-side passage 27 connected to a discharge passage 28, and the secondary-side passage 27 and the primary-side passage 25 are connected via a passage coupler 26. The tool seating confirmation device 7 is configured so that air sent from the air supply source 21 flows through the air supply passage from the supply-side passage 22 to the primary-side passage 25, the secondary-side passage 27, and the discharge passage 28, and is then released into the atmosphere. When the flange portion 811 of the tool holder 81 overlaps the seating surface 131, the opening of the discharge passage 28 is blocked and the flow of air is stopped, causing the internal pressure to rise and activating the pressure switch 24.

[0014] The air supply flow paths (22, 25, 27, 28) that constitute the tool seating confirmation device 10 are formed from the housing 4 to the spindle 3, but are divided by the presence of a gap 20 at the boundary. Therefore, if this is left as is, sufficient pressure to activate the pressure switch 24 will not be generated in the flow paths. Therefore, the tool seating confirmation device 10 is configured such that a flow path connector 26 that connects the flow paths at the gap 20 is provided on the housing 4 side, preventing air leakage when tool seating is confirmed.

[0015] The flow path coupler 26 has a spool 32 slidably inserted into a main body 31. A tapped inlet 311 is formed at one end of the main body 31, and a screw cap 33 is screwed in to close the inlet. A primary connection hole 313 communicating with the primary flow path 25 is formed at the side of the main body 31, and a guide hole 315 for the secondary flow path 27 is formed at the end opposite the inlet 311. The spool 32 has a cylindrical portion 321 and a flange portion 323, and the flange portion 323 slides on the inner surface of the main body 31, while the tip of the cylindrical portion 321 slides in the guide hole 315. The spool 32 has a flow path 325 penetrating through its center.

[0016] Flange portion 323 of spool 32 is biased by spring 35 placed inside main body 31, and in the normal state shown in Fig. 3, flow path 325 is blocked by screw cap 33. In particular, screw cap 33 has a convex shape, and its protrusion 331 blocks flow path 325, thereby increasing the area on which air pressure acts on flange portion 323. Then, during seating confirmation shown in Fig. 4, spool 32 is pushed by the pressure of air sent from air supply source 21 and displaces, resulting in a seating confirmation state in which the tip of spool 32 is inserted into recess 271 formed at the end of secondary-side flow path 27.

[0017] In the tool seating confirmation device 10, when the spool 32 is in the seating confirmation state shown in FIG. 4 , the airtightness of the air supply flow paths (22, 25, 27, 28) is maintained, thereby accurately confirming the seating of the tool 80. However, in the past, the seating confirmation state of the spool 32 was not stable, which sometimes took a long time to confirm the seating, resulting in inaccurate confirmation. Therefore, the flow path coupler 26 of this embodiment has been improved to stabilize the seating confirmation state, and a breathing hole 317 is formed through the side of the main body 31 to allow air to flow in and out of the space 36 between the main body 31, in which the spring 35 is incorporated, and the spool 32.

[0018] Next, the operation of the tool seating confirmation device 10 will be described. The tool spindle device 1 provided in the machine tool automatically changes tools using the ATC. At that time, the tool seating confirmation device 10 determines whether or not the tool 80 used to machine the workpiece is securely attached to the spindle 3. When the tool 80 is attached, the flange portion 811 of the tool holder 81 comes into close contact with the seating surface 131, blocking the opening of the air supply flow path (22, 25, 27, 28). Therefore, by switching the electromagnetic on-off valve 23, which is in the closed state shown in FIG. 3, to the state shown in FIG. 4, air is supplied from the air supply source 21 to the supply-side flow path 22 and further flows to the primary-side flow path 25.

[0019] As shown in Fig. 3, when the electromagnetic on-off valve 23 is closed, the spool 32 is pressed against the screw cap 33, blocking the flow path 325. When air flows in by switching the electromagnetic on-off valve 23, the spool 32 is pushed by the air pressure acting on the flange portion 323 and displaced to the position shown in Fig. 4. That is, the tip of the spool 32 inserted into the recess 271 of the secondary-side flow path 27 abuts against the bottom of the recess, and the primary-side flow path 25 and the secondary-side flow path 27 are connected by the flow path 325 that crosses the gap 20 between the housing 4 and the spindle 3.

[0020] Air sent from the air supply source 21 into the air supply passages (22, 25, 27, 28) is not released because the opening of the exhaust passage 28 is blocked by the tool holder 81. As a result, the internal pressure of the passages rises and, when it exceeds a preset threshold, activates the pressure switch 24. A detection signal is sent from the pressure switch 24 to the control device of the machine tool, which confirms that the tool 80 is correctly attached. After the seating confirmation is complete, the solenoid on-off valve 23 is switched as shown in FIG. 3 to cut off the air supply to the primary passage 25. Then, as the internal pressure of the passages decreases, the spool 32 is returned by the biasing force of the spring 35, and the spool 32 is removed from the gap 20 between the housing 4 and the spindle 3.

[0021] In the tool seating confirmation device 10 of this embodiment, the spool 32 of the flow path coupler 26 is smoothly displaced by air pressure, making it possible to stably maintain the seating confirmation state shown in Fig. 4. The time required for the pressure in the air supply flow paths (22, 25, 27, 28) to exceed the threshold value set for the pressure switch 24 is shortened, making it possible to shorten the time required to confirm the seating of the tool. In particular, this effect can be achieved by the simple configuration of the breathing hole 317.

[0022] In the conventional structure without the breathing hole 317, the seating confirmation state of the spool 32 was unstable. This is thought to be because the space 36 surrounded by the main body 31 incorporating the spring 35 and the spool 32 was highly airtight. That is, when the spool 32 was displaced and the space 36 was compressed during seating confirmation, the pressure difference between both sides of the flange portion 323 became smaller, and the spring 35 pushed back the spool 32. As a result, air leaked from the gap 20, preventing the internal pressure of the flow path from increasing sufficiently. As a result, the pressure of the supplied air against the flange portion 323 and the biasing force of the spring 35 pushed against each other, causing the spool 32 to move erratically to the position shown in FIG. 4.

[0023] Therefore, in the flow path coupler 26 of this embodiment, the breathing hole 317 is formed in the main body 31, so that when the spool 32 is displaced during seating confirmation and the space 36 is compressed, air is pushed out. Therefore, the spool 32 is smoothly displaced by air pressure, thereby achieving the above effect. Because the flow path coupler 26 is incorporated into the housing 4, the improvement of forming the breathing hole 317 in the main body 31 can be easily performed.

[0024] Although one embodiment of the present invention has been described, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0025] 1...Tool spindle device 3...Spindle 4...Housing 5...Spindle motor 10...Tool seating confirmation device 13...Seating member 21...Air supply source 22...Supply side flow path 23...Solenoid on-off valve 24...Pressure switch 25...Primary side flow path 26...Flow path coupler 27...Secondary side flow path 28...Discharge flow path 31...Main body 32...Spool 33...Screw cap 35...Spring 36...Space 80...Tool 81...Tool holder 317...Breathing hole

Claims

1. an air flow path formed from a housing of the tool spindle device to a seating surface of a spindle that rotates with a tool attached; an air supply source that supplies air to the air flow path; an on-off valve connected to the air flow path; a pressure sensor connected to the air flow path; a flow path connector provided on the housing side, the flow path connector having a flow path formed in the center thereof and a tip end of a spool that is displaced by air pressure inserted into recesses formed at ends of a primary side flow path formed in the housing and a secondary side flow path formed in the spindle, among the air flow paths, and connected to the spool, the flow path connector having a breathing hole formed therein that allows air to be let in and out of a space in which a spring that urges the spool against air pressure is incorporated; A tool seating confirmation device having the same.

2. 2. The tool seating confirmation device according to claim 1, wherein the flow path coupler is incorporated into the housing, and the spool has a cylindrical portion whose tip is inserted into the guide hole and a flange portion that receives air pressure supplied from the primary side connection hole, and the flow path coupler is incorporated into a main body having a primary side connection hole for the primary side flow path and a guide hole for the secondary side flow path, and the spool has a flange portion that receives air pressure supplied from the primary side connection hole and is slidably inserted into the main body, and the breathing hole is formed in the main body.

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