Air pressure confirmation device

Abstract

The purpose of the present disclosure is to make it possible to confirm a decrease in air pressure without providing a pressure sensor. This air pressure confirmation device confirms the air pressure of a clamp device. The clamp device switches, via air pressure, from a first state, which is one of a clamped state in which clamping of a rotary table in a machine tool is performed and an unclamped state in which said clamping is released, to a second state, which is the other one of said states. The air pressure confirmation device comprises a state confirmation unit and a warning unit. The state confirmation unit confirms the state of the clamp device at a timing which is instructed for the second state and which is within a prescribed confirmation timing. The warning unit provides a warning that air pressure is decreasing, on the condition that the state confirmation unit has confirmed a state different from the second state at normal times.

Description

Air pressure check device

[0001] The present disclosure relates to an air pressure checking device that is installed in a clamping device that clamps a rotary table of a machine tool.

[0002] Among clamping devices, there are those that use air pressure to switch between a clamped state in which a rotary table in a machine tool is clamped and an unclamped state in which the clamp is released, and the other state.

[0003] JP 2009-248242 A

[0004] In a clamping device that uses air pressure to change from a clamped state to an unclamped state, if the supplied air pressure drops, the following problem may occur: the device may go into a clamped state when it should be in an unclamped state, causing the brake to drag, which can lead to brake component failure, cutting fluid intrusion, and a shortened seal life.

[0005] On the other hand, in a clamping device that uses air pressure to change from an unclamped state to a clamped state, if the supplied air pressure drops, the following problems may occur: the device may go into an unclamped state when it should be clamped, or the clamping force may be insufficient, which may result in the intrusion of cutting fluid or a shortened lifespan of the seal.

[0006] For these reasons, it is desirable to provide a clamping device of this type with a means for checking for a drop in the supplied air pressure. One possible means for doing so is to incorporate a pressure sensor that detects the air pressure into the rotary table. However, with this method, incorporating a pressure sensor around the rotary table complicates the structure around the rotary table, which can lead to increased costs.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to make it possible to check for a drop in air pressure without providing a pressure sensor.

[0008] The air pressure checking device of the present disclosure is an air pressure checking device for checking the air pressure of a clamping device that switches from a first state, which is one of two states in a machine tool, a clamped state in which a rotary table is clamped, and an unclamped state in which the clamp is released, to a second state, which is the other of the two states, by air pressure, and includes: a state checking unit that checks the state of the clamping device at a timing commanded to the second state within a predetermined checking timing; and a warning unit that issues a warning that the air pressure is decreasing, on condition that the state checking unit checks a state that is different from the second state in normal times.

[0009] FIG. 1 is a configuration diagram showing an air pressure checking device and its periphery according to a first embodiment. FIG. 1 is a configuration diagram showing a clamping device and its periphery. FIG. 2 is a flowchart showing the flow of an air pressure checking operation at the timing of starting operation. FIG. 3 is a flowchart showing the flow of an air pressure checking operation at the timing of restarting operation. FIG. 4 is a flowchart showing the flow of an air pressure checking operation at the timing of changing a tool. FIG. 5 is a configuration diagram showing a clamping device and its periphery according to a second embodiment. FIG. 6 is a flowchart showing the flow of an air pressure checking operation at the timing of starting operation. FIG. 7 is a flowchart showing the flow of an air pressure checking operation at the timing of restarting operation. FIG. 8 is a flowchart showing the flow of an air pressure checking operation at the timing of changing a tool. FIG. 9 is a flowchart showing the flow of an air pressure checking operation at the timing of starting operation according to a third embodiment. FIG. 10 is a flowchart showing the flow of an air pressure checking operation at the timing of restarting operation. FIG. 11 is a flowchart showing the flow of an air pressure checking operation at the timing of changing a tool.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments and can be appropriately modified and implemented within the scope of the present disclosure.

[0011] 1, an air pressure checking device 90 of this embodiment is part of a machine tool 100. The machine tool 100 cuts a workpiece with a tool attached to a spindle. The machine tool 100 is equipped with a tool changer for changing the tool attached to the spindle with another tool.

[0012] Furthermore, the machine tool 100 is equipped with a display 20, a numerical control device 30, a servo control device 40, a rotary table 50, a clamp control device 60, and a clamp device 70, which will be described below.

[0013] The display 20 displays a screen based on information from the numerical control device 30. The display 20 displays commands to the numerical control device 30, various current states of the machine tool 100, and the like.

[0014] The numerical control device 30 transmits commands to various control devices including the servo control device 40 and the clamp control device 60 based on the input machining program 33. In response to this, the numerical control device 30 controls the machine tool 100. As a result, the numerical control device 30 starts operation of the machine tool 100 based on the control of the machine tool 100 based on the machining program 33. The numerical control device 30 also replaces the tool attached to the spindle based on the control of the machine tool 100 based on the machining program 33.

[0015] Furthermore, when a predetermined emergency stop button is pressed, numerical control device 30 stops the operation of machine tool 100. At this time, the excitation of the main motor that drives machine tool 100 is turned from ON to OFF. Thereafter, when the emergency stop is released, the excitation of the motor is turned from OFF to ON.

[0016] The rotary table 50 is a part or all of a workpiece moving device for moving the workpiece relative to the spindle unit. The rotary table 50 is driven in a rotational direction by a predetermined table motor 50 a. The servo control device 40 controls the rotary table 50 by controlling the table motor 50 a based on commands from the numerical control device 30.

[0017] The clamping device 70 is configured to be able to clamp the rotary table 50. Hereinafter, the state in which the rotary table 50 is clamped by the clamping device 70 will be referred to as the "clamped state," and the state in which the clamping is released will be referred to as the "unclamped state." In this embodiment, the "clamped state" may be read as the "first state," and the "unclamped state" may be read as the "second state."

[0018] Specifically, as shown in Fig. 2, the clamping device 70 includes a spring 72, a piston 75, and an air pressure supply system 78. Hereinafter, the predetermined position will be referred to as the "clamping position," and another predetermined position will be referred to as the "unclamping position." Furthermore, the direction from the unclamping position side toward the clamping position side will be referred to as the "clamping direction Dc," and the opposite direction will be referred to as the "unclamping direction Du."

[0019] The piston 75 is configured to be movable between a clamping position and an unclamping position. When the piston 75 is located in the clamping position, the clamping members of the clamp device 70 clamp the disk on the rotary table 50, thereby establishing a clamped state. On the other hand, when the piston 75 is located in the unclamping position, the clamping of the disk by the clamping members is released, thereby establishing an unclamping state.

[0020] More specifically, in this embodiment, the piston 75 is biased in the clamping direction Dc by the restoring force of the spring 72. The piston 75 is also biased in the unclamping direction Du by air pressure from the air pressure supply system 78.

[0021] Therefore, when the air pressure from the air pressure supply system 78 is OFF, the piston 75 is placed in the clamped position by the restoring force of the spring 72. When the air pressure is switched from OFF to ON, the air pressure moves the piston 75 in the unclamping direction Du against the restoring force of the spring 72 and places it in the unclamped position, thereby switching from the clamped state to the unclamped state.

[0022] On the other hand, when the air pressure is switched from ON to OFF, the piston 75 moves from the unclamped position in the clamping direction Dc to the clamped position by the restoring force of the spring 72. This switches the state from unclamped to clamped.

[0023] The clamp control device 60 shown in FIG. 1 controls the clamp device 70 by controlling the air pressure supply system 78 based on a command from the numerical control device 30 .

[0024] The air pressure checking device 90 is a device for checking the air pressure of the clamp device 70 described above. Hereinafter, the operation for checking the air pressure will be referred to as the "air pressure checking operation." The air pressure checking operation is performed at predetermined checking timings. The checking timings include the operation start timing, operation restart timing, and tool change timing, which will be described below.

[0025] The operation start timing is the timing at which operation of machine tool 100 is started based on machining program 33. The operation restart timing is the timing at which the emergency stop state of machine tool 100 is released and the excitation of the motor described above is changed from OFF to ON. The tool change timing is the timing at which a tool is changed based on machining program 33 while machine tool 100 is operating.

[0026] The air pressure checking device 90 includes an original command storage unit 91, a command switching unit 92, a status checking unit 93, and a warning unit 97. The original command storage unit 91, the command switching unit 92, and the status checking unit 93 are each configured as part of the numerical control device 30. On the other hand, the warning unit 97 is configured as part of the display.

[0027] First, a description will be given of the state confirmation unit 93 and the warning unit 97. Hereinafter, a command to change to a clamped state will be referred to as a "clamp command", and a command to change to an unclamped state will be referred to as an "unclamp command".

[0028] The state confirmation unit 93 confirms the state of the clamp device 70 when an unclamping command is issued within the confirmation timing. Specifically, the state confirmation unit 93 repeatedly issues a command to rotate the turntable 50 forward and backward. The state of the turntable 50 is confirmed based on position information of the turntable 50 in the rotational direction at that time. That is, if the positional fluctuation of the turntable 50 in the rotational direction is greater than a predetermined standard, it is determined to be in an unclamped state, and if the fluctuation is smaller than the predetermined standard, it is determined to be in a clamped state. Note that the position information in the rotational direction at this time is acquired, for example, by an encoder 59 or the like installed on the turntable 50.

[0029] The warning unit 97 displays a warning that the air pressure is decreasing, provided that the state confirmation unit 93 confirms the clamped state at the timing when the unclamping command is issued.

[0030] Next, the original command storage unit 91 and the command switching unit 92 will be described.

[0031] At the beginning of the confirmation timing, the original command storage unit 91 stores the original command as the current command regarding the state of the clamp device 70. Thereafter, the command switching unit 92 changes the command regarding the state of the clamp device 70 to an unclamping command. In the unclamping command state, the state confirmation unit 93 checks the state of the clamp device 70 as described above. Thereafter, the command switching unit 92 changes the command regarding the state of the clamp device 70 to the original command stored in the original command storage unit 91.

[0032] Therefore, for example, if the original command is a clamp command, the command switching unit 92 switches the command regarding the state of the clamp device 70 to an unclamping command. In the unclamping command state, the state confirmation unit 93 confirms the state of the clamp device 70. Thereafter, the command switching unit 92 changes the command regarding the state of the clamp device 70 from the unclamping command back to the original command, i.e., back to the clamping command.

[0033] On the other hand, if the original command is an unclamping command, the command switching unit 92 maintains the original command by changing the command regarding the state of the clamp device 70 to an unclamping command. In this unclamping command state, the state confirmation unit 93 checks the state of the clamp device 70. Thereafter, the command switching unit 92 maintains the unclamping command by changing the command regarding the state of the clamp device 70 back to the original command, i.e., an unclamping command.

[0034] Next, the flow of the air pressure checking operation at the start of operation will be described with reference to the flowchart of FIG.

[0035] First, in S11, it is determined whether or not machine tool 100 is currently out of operation based on machining program 33. If the determination is negative, that is, if machine tool 100 is in operation, processing repeats S11. On the other hand, if the determination is positive in S11, that is, if machine tool 100 is out of operation, processing proceeds to S12.

[0036] In S12, it is determined whether or not machine tool 100 is currently operating based on machining program 33. If the determination is negative, that is, if machine tool 100 is not operating, S12 is repeated. On the other hand, if the determination is positive in S12, that is, if machine tool 100 is operating, it is determined that it is time to start operation, and the process proceeds to S41.

[0037] In S41, the original command is stored, which is the current command regarding the state of the clamp device 70. That is, if the current command is a clamp command, the clamp command is stored, and if it is an unclamp command, the unclamp command is stored.

[0038] In the next step S52, the command for the state of the clamp device 70 is changed to an unclamping command. That is, if the current command is already an unclamping command, the unclamping command is maintained. On the other hand, if the current command is a clamping command, it is switched to an unclamping command.

[0039] In the next step S53, the state confirmation unit 93 determines whether the clamp device 70 is in a clamped state. If the determination is affirmative, i.e., if the clamp device 70 is in a clamped state, it is determined that the air pressure has dropped, and the process proceeds to step S54. In step S54, the warning unit 97 displays a warning that the air pressure has dropped. Thereafter, the process proceeds to step S55. On the other hand, if the determination is negative in step S53, i.e., if the clamp device 70 is in an unclamped state, it is determined that the clamp device 70 is normal, and the process skips step S54 and proceeds to step S55.

[0040] In S55, it is determined whether the original command stored in the original command storage unit 91 is a clamp command. If the determination is affirmative, that is, if the original command is a clamp command, the process proceeds to S56. In S56, the command regarding the state of the clamp device 70 is switched from an unclamping command to a clamping command. Thereafter, the process returns to the initial S11. On the other hand, if the determination is negative in the above-mentioned S55, that is, if the original command is an unclamping command, the process skips S56, that is, returns to the initial S11 while maintaining the unclamping command.

[0041] Next, the flow of the air pressure checking operation at the timing of restarting operation will be described with reference to the flowchart of FIG.

[0042] First, in S21, it is determined whether the excitation of the motor that drives machine tool 100 is OFF. If the determination is negative, that is, if the excitation of the motor is ON, S21 is repeated. On the other hand, if the determination is positive in S21, that is, if the excitation of the motor is OFF, the process proceeds to S22.

[0043] In S22, it is determined whether the excitation of the motor is ON. If the determination is negative, that is, if the excitation of the motor is OFF, S22 is repeated. On the other hand, if the determination is positive in S22, that is, if the excitation of the motor is ON, it is determined that it is time to resume operation, and the process proceeds to S41.

[0044] The flow from S41 onwards is the same as that of the air pressure confirmation operation at the start of operation shown in FIG.

[0045] Next, the flow of the air pressure confirmation operation at the timing of tool change will be described with reference to the flowchart in Fig. 5. Hereinafter, the timing when the current tool is maintained without being changed will be referred to as "tool maintenance", and the timing when the tool is changed based on the machining program 33 will be referred to as "tool change".

[0046] First, in S31, it is determined whether or not the tool is being maintained based on the machining program 33. If the determination is negative, that is, if the tool is being replaced, the process repeats S31. On the other hand, if the determination is positive in S31, that is, if the tool is being maintained, the process proceeds to S32.

[0047] In S32, it is determined whether or not a tool is being changed based on the machining program 33. If the determination is negative, that is, if the tool is being maintained, S32 is repeated. On the other hand, if the determination is positive in S32, that is, if the tool is being changed, it is determined that it is time to change the tool, and the process proceeds to S41.

[0048] The flow from S41 onwards is the same as that of the air pressure confirmation operation at the start of operation shown in FIG.

[0049] According to this embodiment, the following effects can be obtained.

[0050] The state confirmation unit 93 shown in FIG. 1 confirms the state of the clamp device 70 when an unclamping command is issued within the confirmation timing. The warning unit 97 issues a warning that the air pressure is decreasing, provided that the state confirmation unit 93 confirms that the clamp device 70 is in a clamped state. Therefore, a decrease in air pressure can be confirmed without providing a pressure sensor or the like in the air pressure supply system 78. This makes it possible to provide an air pressure confirmation device 90 that is simple in structure and low in cost.

[0051] The confirmation timing includes the operation start timing, which is the timing when the operation of machine tool 100 is started based on the machining program. Therefore, the air pressure can be confirmed at the operation start timing.

[0052] The confirmation timing includes the operation resumption timing, which is the timing when the emergency stop state of machine tool 100 is released and the excitation of the motor that drives machine tool 100 is turned from OFF to ON. Therefore, the air pressure can be checked at the operation resumption timing.

[0053] The confirmation timing includes tool change timing, which is the timing when a tool of machine tool 100 is changed based on the machining program while machine tool 100 is in operation. Therefore, the air pressure can be confirmed at the tool change timing.

[0054] At the confirmation timing, the original command storage unit 91 stores the original command as the current command regarding the state of the clamp device 70. The command switching unit 92 issues an unclamping command after the original command storage unit 91 stores the original command. After that, the state of the clamp device 70 is confirmed by the state confirmation unit 93, the command switching unit 92 changes the command regarding the state of the clamp device 70 to the original command. Therefore, even if the original command is a clamping command, by switching to an unclamping command, it is possible to confirm the state of the air pressure. Moreover, it is possible to return to the original clamping command thereafter.

[0055] The state confirmation unit 93 repeatedly issues commands for forward and reverse rotation of the turntable 50, and confirms the state of the clamping device 70 based on the positional fluctuation in the rotational direction of the turntable 50. Therefore, even without providing a position sensor or the like on the piston 75, it is possible to confirm whether the turntable 50 is in the clamped state or the unclamped state based on the positional fluctuation in the rotational direction of the turntable 50.

[0056] Second Embodiment Next, a second embodiment will be described with reference to Figures 6 to 9. This embodiment will be described based on the first embodiment, focusing on differences from the first embodiment, and descriptions of the same or similar aspects to the first embodiment will be omitted as appropriate.

[0057] 6, in the clamp device 70 of this embodiment, the piston 75 is urged in the clamping direction Dc by air pressure from the air pressure supply system 78, which is the opposite of the first embodiment. The piston 75 is urged in the unclamping direction Du by the restoring force of the spring 72. Therefore, in this embodiment, the unclamped state is switched to the clamped state by air pressure. Note that in this embodiment, the "unclamped state" may be read as the "first state" and the "clamped state" may be read as the "second state."

[0058] Next, the flow of the air pressure confirmation operation at the start of operation will be described with reference to the flowchart in Figure 7. Compared to the first embodiment shown in Figure 3, this embodiment differs from the first embodiment in that steps S62 to S66 are included instead of steps S52 to S56.

[0059] In S62, the command for the state of the clamp device 70 is changed to a clamp command. That is, if the current command is already a clamp command, the clamp command is maintained. On the other hand, if the current command is an unclamp command, it is switched to a clamp command.

[0060] In the next step S63, the state confirmation unit 93 determines whether the clamp device 70 is in a clamped state. If the determination is negative, i.e., if the clamp device 70 is in an unclamped state, it is determined that the air pressure has dropped, and the process proceeds to step S64. In step S64, the warning unit 97 displays a warning that the air pressure has dropped. Thereafter, the process proceeds to step S65. On the other hand, if the determination is positive in step S63, i.e., if the clamp device 70 is in a clamped state, it is determined that the clamp device 70 is normal, and the process skips step S64 and proceeds to step S65.

[0061] In S65, it is determined whether the original command stored in the original command storage unit 91 is an unclamping command. If the determination is affirmative, that is, if the original command is an unclamping command, the process proceeds to S66. In S66, the command regarding the state of the clamp device 70 is switched from a clamping command to an unclamping command. Thereafter, the process returns to the initial step S11. On the other hand, if the determination is negative in S65, that is, if the original command is a clamping command, the process skips S66, that is, returns to the initial step S11 while maintaining the clamping command.

[0062] Next, the flow of the air pressure confirmation operation at the start of operation will be described with reference to the flowchart in Figure 8. Compared to the first embodiment shown in Figure 4, this embodiment differs from the first embodiment in that the above-mentioned steps S62 to S66 are included instead of steps S52 to S56.

[0063] Next, the flow of the air pressure checking operation at the tool change timing will be described with reference to the flowchart in Figure 9. Compared to the first embodiment shown in Figure 5, this embodiment differs from the first embodiment in that the above-mentioned steps S62 to S66 are included instead of steps S52 to S56.

[0064] The configuration and effects of this embodiment are summarized below. In this embodiment shown in FIG. 6 , the air pressure changes the state from the unclamped state to the clamped state, in contrast to the first embodiment. The state confirmation unit 93 shown in FIG. 1 checks the state of the clamp device 70 when a clamp command is issued within the confirmation timing. The warning unit 97 displays a warning that the air pressure is decreasing, provided that the state confirmation unit 93 confirms that the clamp device 70 is in the unclamped state. Therefore, in this embodiment as well, as in the first embodiment, a decrease in air pressure can be confirmed without providing a pressure sensor or the like in the air pressure supply system 78.

[0065] [Third Embodiment] Next, a third embodiment will be described with reference to Figures 10 to 12. This embodiment will be described based on the second embodiment, focusing on differences from the second embodiment, and descriptions of the same or similar aspects to the second embodiment will be omitted as appropriate.

[0066] Hereinafter, when the clamp force in the clamped state reaches a predetermined standard, the clamp force is referred to as "sufficient," and when the clamp force does not reach the predetermined standard, the clamp force is referred to as "insufficient." The state confirmation unit 93 of this embodiment determines whether the clamp force is sufficient.

[0067] Specifically, in this embodiment, the state check unit 93 also repeatedly commands the turntable 50 to rotate forward and backward. Whether the clamping force is sufficient is checked based on the position information of the turntable 50 in the rotational direction at that time. That is, if the positional fluctuation of the turntable 50 in the rotational direction is greater than a predetermined standard that is smaller than those in the first and second embodiments, the clamping force is determined to be insufficient. If the positional fluctuation is smaller than the predetermined standard, the clamping force is determined to be sufficient. Therefore, for example, even if the positional fluctuation is smaller than that in the unclamped state, if the positional fluctuation is larger than that in the normally clamped state, the clamping force may be determined to be insufficient.

[0068] Next, the flow of the air pressure confirmation operation at the start of operation will be described with reference to the flowchart of Figure 10. Compared to the second embodiment shown in Figure 7, this embodiment differs from the second embodiment in that S63b is included instead of S63.

[0069] That is, in S63b, the status check unit 93 determines whether the clamping force is sufficient. If the determination is negative, i.e., if the clamping force is insufficient, the process proceeds to S64. On the other hand, if the determination is positive in S63, i.e., if the clamping force is sufficient, the clamp device 70 is determined to be normal, and the process skips S64 and proceeds to S65.

[0070] Next, the flow of the air pressure confirmation operation at the start of operation will be described with reference to the flowchart in Figure 11. Compared to the second embodiment shown in Figure 8, this embodiment differs from the second embodiment in that S63b described above is included instead of S63.

[0071] Next, the flow of the air pressure checking operation at the tool change timing will be described with reference to the flowchart of Fig. 12. Compared to the second embodiment shown in Fig. 9, this embodiment differs from the second embodiment in that the above-mentioned S63b is included instead of S63.

[0072] The configuration and effects of this embodiment are summarized below. In this embodiment, the status confirmation unit 93 confirms whether the clamping force of the clamp device 70 is sufficient when a clamp command is issued within the confirmation timing. The warning unit 97 displays a warning that the air pressure is decreasing if the status confirmation unit 93 confirms that the clamping force is insufficient. Therefore, a decrease in air pressure can be confirmed more accurately than in the second embodiment.

[0073] Other Embodiments The above-described embodiment can be modified, for example, as follows.

[0074] 1 may issue the warning by other visual means such as a warning lamp instead of, or in addition to, issuing a warning of a drop in air pressure by displaying it on the display 20. Furthermore, the warning unit 97 may issue the warning by audio means such as an audio warning sound or announcement instead of, or in addition to, such visual means as a display or warning lamp. Furthermore, the warning unit 97 may issue the warning by tactile means such as vibration instead of, or in addition to, such visual or audio means.

[0075] The confirmation timing may include only one or two of the three timings of the operation restart timing, the operation restart timing, and the tool change timing, or may include timings other than the three timings.

[0076] According to the above embodiment, the air pressure checking device 90 described in the following appendices 1 to 10 can be realized.

[0077] [Supplementary Note 1] For a clamping device (70) that switches from a first state, which is one of a clamped state in which a rotary table (50) in a machine tool (100) has been clamped, and an unclamped state in which the clamping has been released, to a second state, which is the other of the two states, by air pressure, the air pressure confirmation device (90) is configured to check the air pressure, and includes: a state confirmation unit (93) that checks the state of the clamping device (70) at a timing instructed to the second state within a predetermined confirmation timing; and a warning unit (97) that issues a warning that the air pressure is decreasing, on condition that the state confirmation unit (93) confirms a state that is different from the second state in normal times.

[0078] [Supplementary Note 2] The air pressure checking device (90) according to Supplementary Note 1, wherein the first state is the clamped state, the second state is the unclamped state, the state checking unit (93) checks the state of the clamping device at a timing when the unclamped state is commanded within the checking timing, and the warning unit (97) issues the warning on the condition that the clamped state is confirmed by the state checking unit (93).

[0079] [Supplementary Note 3] The air pressure checking device (90) according to Supplementary Note 1, wherein the first state is the unclamped state, the second state is the clamped state, the state checking unit (93) checks the state of the clamp device (70) at a timing when the clamped state is commanded within the checking timing, and the warning unit (97) issues the warning on condition that the unclamped state is checked by the state checking unit.

[0080] [Supplementary Note 4] The air pressure checking device (90) according to Supplementary Note 1, wherein the first state is the unclamped state, the second state is the clamped state, the state checking unit (93) checks the state of the clamp device (70) at a timing when the clamped state is commanded within the checking timing, and the warning unit (97) issues the warning on the condition that the state checking unit has confirmed that the clamp force has not reached a predetermined standard.

[0081] [Supplementary Note 5] The air pressure checking device (90) according to any one of Supplementary Notes 1 to 4, wherein the checking timing includes an operation start timing as a timing when operation of the machine tool (100) is started based on a predetermined machining program (33).

[0082] [Supplementary Note 6] The air pressure checking device (90) according to any one of Supplementary Notes 1 to 5, wherein the checking timing includes operation resumption timing, which is timing when an emergency stop state of the machine tool (100) is released and excitation of a motor that drives the machine tool (100) is turned from OFF to ON.

[0083] [Supplementary Note 7] The air pressure checking device (90) according to any one of Supplementary Notes 1 to 6, wherein the checking timing includes a tool change timing as a timing when a tool of the machine tool (100) is changed based on a predetermined machining program while the machine tool (100) is in operation.

[0084] [Supplementary Note 8] The air pressure checking device (90) according to any one of Supplementary Notes 1 to 7, comprising: an original command storage unit (91) that stores an original command as a current command regarding the state of the clamping device (70) at the confirmation timing; and a command switching unit (92) that issues a command to the second state after the original command storage unit (91) has stored the original command, and that changes the command regarding the state of the clamping device (70) to the original command after the state checking unit (93) has checked the state of the clamping device (70).

[0085] [Appendix 9] The air pressure checking device (90) according to any one of Appendices 1 to 8, wherein the state checking unit repeatedly commands forward and reverse rotation of the rotary table (50) and checks the state of the clamping device (70) based on positional fluctuations in the rotational direction of the rotary table (50).

[0086] 33 Machining program 50 Rotary table 70 Clamping device 90 Air pressure checking device 91 Original command storage unit 92 Command switching unit 93 Status checking unit 97 Warning unit 100 Machine tool

Claims

1. An air pressure confirmation device for a clamping device in a machine tool that switches from a first state, which is one of two states in which a rotary table is clamped, and an unclamped state in which the clamp is released, to a second state, which is the other of the two states, using air pressure, comprising: a state confirmation unit that confirms the state of the clamping device at a timing commanded to the second state within a predetermined confirmation timing; and a warning unit that issues a warning that the air pressure is decreasing, on condition that the state confirmation unit confirms a state that is different from the second state in normal times.

2. An air pressure checking device as described in claim 1, wherein the first state is the clamped state, the second state is the unclamped state, the state checking unit checks the state of the clamping device at the timing when the unclamped state is commanded within the checking timing, and the warning unit issues the warning on the condition that the clamped state has been confirmed by the state checking unit.

3. An air pressure checking device as described in claim 1, wherein the first state is the unclamped state, the second state is the clamped state, the state checking unit checks the state of the clamping device at the timing commanded to the clamped state within the checking timing, and the warning unit issues the warning on the condition that the unclamped state has been confirmed by the state checking unit.

4. An air pressure checking device as described in claim 1, wherein the first state is the unclamped state, the second state is the clamped state, the state checking unit checks the state of the clamping device at the timing commanded to the clamped state within the checking timing, and the warning unit issues the warning on the condition that the state checking unit confirms that the clamp force does not reach a predetermined standard.

5. An air pressure checking device according to any one of claims 1 to 4, wherein the checking timing includes operation start timing, which is the timing when operation of the machine tool is started based on a predetermined machining program.

6. An air pressure checking device according to any one of claims 1 to 5, wherein the checking timing includes the timing of restarting operation when the emergency stop state of the machine tool is released and the excitation of the motor that drives the machine tool is turned from OFF to ON.

7. An air pressure checking device according to any one of claims 1 to 6, wherein the checking timing includes tool change timing, which is the timing when a tool of the machine tool is changed based on a predetermined machining program while the machine tool is in operation.

8. An air pressure checking device as set forth in any one of claims 1 to 7, comprising: an original command storage unit that stores an original command as a current command regarding the state of the clamping device at the checking timing; and a command switching unit that commands the second state after the original command is stored by the original command storage unit, and changes the command regarding the state of the clamping device to the original command after the state checking unit checks the state of the clamping device.

9. An air pressure checking device according to any one of claims 1 to 8, wherein the status checking unit repeatedly commands forward and reverse rotation of the rotary table and checks the status of the clamping device based on positional fluctuations in the rotational direction of the rotary table.

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