JP7637261B2 - Seating determination device and machine tool - Google Patents

Description

This specification relates to a seating determination device and a machine tool.

Conventionally, a seating determination method has been disclosed, for example in Patent Document 1 below. In the conventional seating determination method, when the back pressure during machining detected by a pressure sensor converges within a predetermined pressure range within a set time and becomes constant, the control device sets a threshold value for machining based on the constant back pressure. In the conventional seating determination method, the control device compares the threshold value for machining related to the back pressure with the back pressure detected by the pressure sensor to determine pass/fail.

JP 2017-7027 A

However, when machining a seated workpiece, the seating state of the workpiece may change depending on the type of machining. Therefore, it is necessary to set an appropriate threshold value for each different type of machining to determine the seating state. However, the above-mentioned conventional seating determination method does not disclose that when setting a threshold value for machining, a threshold value for each different type of machining is set.

The present specification aims to provide a seating determination device that can monitor the seating state of a workpiece for each different machining process.

This specification discloses a seating determination device that includes a detection device that detects a physical quantity that changes depending on the seating state of a workpiece, a determination unit that determines the seating state based on the physical quantity and a threshold value set for the physical quantity to determine the seating state during processing of the workpiece, and a setting unit that sets the threshold value for each different processing of the workpiece.

With the seating determination device, a threshold value can be set for each different processing by the setting unit. Therefore, the seating determination device can constantly monitor the seating state in detail for each different processing, thereby improving the accuracy of processing the workpiece.

FIG. 2 is a side view for explaining a configuration of a machine tool equipped with a seating determination device. FIG. 2 is a partial cross-sectional view for explaining a configuration of a detection device of the seating determination device of FIG. 1 . 2 is a functional block diagram for explaining a configuration of a control device of the seating determination device of FIG. 1 . 4 is a diagram for explaining input of a threshold value for each machining in the control device of FIG. 3 . FIG. 11A and 11B are diagrams for explaining threshold values set for different types of processing (for different types of processing). 11A and 11B are diagrams for explaining threshold values set for different types of processing; FIG. 11 is a partial cross-sectional view for explaining a configuration of a detection device of a seating occupancy determination device of a first modified example. FIG. 13 is a functional block diagram for explaining a configuration of a control device of a seating occupancy determination device according to a first modified example. FIG. 1 is a diagram for explaining physical quantities.

The seating determination device and the machine tool will be described below with reference to the drawings. In this embodiment, a machining system formed with an automatic work transfer machine that transfers a work to a machine tool having a seating determination device will be described as an example.

1. Overall configuration of the machining system 10 As shown in FIG. 1, the machining system 10 includes a base 20 and a machine tool 30 that is provided on the base 20 and performs various machining processes on the workpiece W. In the present embodiment, a case in which one machine tool 30 is provided on the base 20 is illustrated, but it is also possible to provide a plurality of machine tools 30 on the base 20. The machining system 10 also includes an articulated robot 50 (hereinafter, sometimes simply referred to as the "robot 50") as an automatic workpiece transport machine that transports the workpiece W before machining to the machine tool 30 and transports the workpiece W after machining from the machine tool 30. Furthermore, the machine tool 30 constituting the machining system 10 is provided with a seating determination device 60 that determines the seating state of the workpiece W carried in by the robot 50.

2. Machine tool 30
The machine tool 30 rotates a workpiece W, which is an object to be machined, or fixes it so that it cannot rotate, and performs different processes, such as cutting and drilling. As shown in Fig. 1, the machine tool 30 has a movable head 41, a headstock 42, a tool table 43, a tool table moving device 44, a processing chamber 45, a traveling chamber 46, and a control device 47. The movable head 41 moves along the Z-axis direction (front-back direction) on rails (not shown) provided on the base 20 via a plurality of wheels 41a.

The headstock 42 rotatably holds the workpiece W. The headstock 42 rotatably supports the spindle 42a, which is arranged horizontally along the Z-axis (front-rear direction). A chuck 42c for holding the workpiece W is provided on a seating portion 42b (so-called abutment) for the workpiece W, which is provided at the tip of the spindle 42a. A detection device 61 of a seating determination device 60, which will be described later, is disposed behind the seating portion 42b in the Z-axis direction. The spindle 42a is rotationally driven by a servo motor 42e via a rotation transmission mechanism 42d, and is rotatable around the Z-axis.

The tool table 43 is a device that holds multiple tools 43a and applies a feed motion to a selected tool 43a. The tool table 43 is a polygonal turret-type tool table (tool rest) and has a tool holding section 43b to which multiple tools 43a for machining the workpiece W are attached. Here, examples of the tools 43a include cutting tools such as a cutting tool, or rotating tools such as an end mill or a drill.

Furthermore, the tool table 43 has a rotation drive unit 43c that rotatably supports the tool holding unit 43b and can fix the swivel-indexed tool 43a, i.e., the tool holding unit 43b. As a result, in the tool table 43, the tool holding unit 43b rotates as the rotation drive unit 43c rotates, and the tool 43a corresponding to each machining of the workpiece W is selected by swivel indexing.

The tool table moving device 44 is a device that moves the tool table 43 and therefore the tool 43a along the X-axis direction (up and down) and the Z-axis direction (front and back). The tool table moving device 44 has an X-axis drive device 44a that moves the tool table 43 along the X-axis direction, and a Z-axis drive device 44b that moves the tool table 43 along the Z-axis direction.

The X-axis drive unit 44a has an X-axis slider 44a1 slidably attached to a column provided on the movable head 41 in the vertical direction, and a servo motor 44a2 for moving the X-axis slider 44a1. The Z-axis drive unit 44b has a Z-axis slider 44b1 slidably attached to the X-axis slider 44a1 in the front-rear direction, and a servo motor 44b2 for moving the Z-axis slider 44b1.

The machining chamber 45 is a space for machining the workpiece W, and houses the chuck 42c and the tool stand 43 (tool 43a, tool holder 43b, rotary drive 43c, and detector 61). The machining chamber 45 is partitioned by a front wall 45a, a ceiling wall 45b, left and right walls, and a rear wall (all not shown). The front wall 45a is formed with an entrance/exit 45a1 through which the workpiece W enters and exits. The entrance/exit 45a1 is opened and closed by a shutter 45c driven by a motor not shown. The open state (open position) of the shutter 45c is indicated by a solid line, and the closed state (closed position) is indicated by a two-dot chain line.

The travel room 46 is a space facing the entrance/exit 45a1 of the processing room 45. The travel room 46 is partitioned by a front wall 45a and a front panel 31. A robot 50 (described later) can travel inside the travel room 46.

The control device 47 mainly includes a CNC (Computer Numerically Controlled), a PLC (Programmable Logic Controller), a servo system, etc., and controls the operation of the rotary drive unit 43c of the machine tool 30, the tool table moving device 44, etc., according to an NC program set for each machining operation. In this embodiment, the control device 47 is connected to a setting device 62 of the seating determination device 60 described later so as to be able to communicate with each other.

3. Robot 50
The robot 50 is movable, and carries the workpiece W before machining into the machine tool 30, and carries the workpiece W after machining out of the machine tool 30. To this end, the robot 50 has a traveling part 51, a main body part 52, and a robot hand 53.

The travelling section 51 travels within the travelling chamber 46. The main body section 52 has a rotating table and an arm section, and by rotating and extending the arm section, the workpiece W is loaded and unloaded from the machining chamber 45, more specifically, the spindle 42a. The robot hand 53 is provided at the tip of the arm section of the main body section 52, and grasps (clamps) and releases (unclamps) the workpiece W.

4. Seating Determination Device 60
1, the seating determination device 60 has a detection device 61 provided on the headstock 42, more specifically, behind the seating portion 42b of the spindle 42a, and a setting device 62 provided below the control device 47. Note that in this embodiment, the setting device 62 is disposed below the control device 47, but the location of the setting device 62 is not limited to this, and it goes without saying that it can be disposed at a position separated from the control device 47.

4-1. Detection device 61
2, the detection device 61 includes a detection hole 611, an air supply pipe 612, and a digital seating sensor 613. A plurality of detection holes 611 are provided in the seating portion 42b. The detection holes 611 are arranged, for example, at equal intervals on a circumference. The detection holes 611 are configured such that when the workpiece W is properly seated on the seating surface 42b1 of the seating portion 42b, the detection holes 611 opening on the seating surface 42b1 are blocked to a certain extent by the back surface W1 of the workpiece W.

The air supply pipe 612 connects the detection hole 611 to an air supply source C, such as a compressor, installed in the factory. A flow control valve Va is connected to the air supply pipe 612 so that the amount of flow throttling can be adjusted. A pressure gauge G that detects the primary pressure supplied from the air supply source C is connected to the primary side (air supply source C side) of the flow control valve Va in the air supply pipe 612.

The digital seating sensor 613 is connected to the secondary side (the seating portion 42b side of the spindle 42a) of the flow control valve Va. The digital seating sensor 613 is formed to include a back pressure gauge 614 and a pressure switch 615. The back pressure gauge 614 detects the back pressure P (see FIG. 3), which is the pressure of the positive pressure air that is ejected from the detection hole 611 at the seating surface 42b1 and supplied toward the back surface W1 of the workpiece W. The back pressure gauge 614 then outputs a digital signal representing the detected back pressure P.

The back pressure P detected by the back pressure gauge 614 is a physical quantity that changes depending on the seating state, which represents the state in which the workpiece W is attached to the seating portion 42b, i.e., the state in which the back surface W1 of the workpiece W is seated facing the seating surface 42b1. Here, an example of an appropriate seating state for the workpiece W is a seating state in which the back surface W1 and the seating surface 42b1 are parallel and close to each other. In the appropriate seating state, the detection hole 611 is blocked by the back surface W1, so the detected back pressure P becomes large.

On the other hand, examples of the seating state of the workpiece W include an inclination of the back surface W1 relative to the seating surface 42b1, or a large distance between the back surface W1 and the seating surface 42b1. In an inappropriate seating state, in other words, a state in which the back surface W1 of the workpiece W is raised above the seating surface 42b1 of the seating portion 42b, all or part of the detection hole 611 is not blocked by the back surface W1, and the detected back pressure P is small.

The pressure switch 615 is a solid-state digital pressure switch, and is connected to the setting device 62 and the control device 47. As described below, the pressure switch 615 has judgment thresholds LV1, LV2, ..., LVn set by the setting device 62, and outputs a normal signal Sn or an abnormal signal Sa (see Figure 3), which is a digital signal, according to the magnitude of the back pressure P detected by the back pressure gauge 614. Here, in this embodiment, the pressure switch 615 functions as a judgment unit and an output unit.

The pressure switch 615 compares the detected back pressure P with threshold values LV1, LV2, ..., LVn set for each different processing (or each different processing content) as described below. Then, when the back pressure P is equal to or greater than the threshold values LV1, LV2, ..., LVn set for each different processing (or each different processing content), the pressure switch 615 outputs a normal signal Sn indicating an appropriate seating state. On the other hand, when the back pressure P is less than the threshold values LV1, LV2, ..., LVn set for each different processing (or each different processing content), the pressure switch 615 outputs an abnormal signal Sa indicating an inappropriate seating state, i.e., a floating state of the workpiece W. Here, the pressure switch 615 as a judgment unit can output an abnormal signal Sa, for example, when the detected back pressure P continues to be less than the threshold values LV1, LV2, ..., LVn for a predetermined time (for example, several seconds).

4-2. Setting device 62
The setting device 62 has, for example, a PLC as a main component, and is capable of communicating with the control device 47. Here, in this embodiment, the setting device 62 acquires machining information J for each different machining from the control device 47 by communication, as shown in FIG. 3. The machining information J is information set for each machining (each machining content), and is, for example, information related to machining of the workpiece W by the tool 43a, including the machining position, machining direction, machining speed, and machining amount per unit time (for example, cutting volume per unit time, etc.) of the tool 43a with respect to the workpiece W. The machining information J can be extracted, for example, from an NC program stored in the control device 47.

As shown in Fig. 3, the setting device 62 includes an input unit 621, a setting unit 622, and a history storage unit 623. The setting device 62 is operated by an operator who performs work using the machine tool 30.

The input unit 621 is a human interface operated by an operator. The input unit 621 inputs the thresholds LV1, LV2, ..., LVn and the reference threshold LVb to the setting unit 622 for each different machining by the machine tool 30, more specifically, for each different machining content for the workpiece W. Below, the input of the thresholds LV1, LV2, ..., LVn and the reference threshold LVb will be explained, but in the explanation, the thresholds LV1, LV2, ..., LVn may be collectively referred to simply as "threshold LV".

As shown in Fig. 4, the input unit 621 displays a display screen 621a that is visually recognized by the operator. On the display screen 621a, a "Work No." that identifies the work W to be processed is displayed, and the back pressure P currently detected by the back pressure gauge 614 is displayed as a "detection value." Furthermore, on the display screen 621a, a selection section 621b for selecting (or allowing direct input of) "processing (processing contents)" and a selection section 621c for selecting (or allowing direct input of) a "threshold value" are displayed.

Here, for "processing (processing content)", the "processing No." is selected and input by operating "+" or "-" using selection unit 621b based on processing information J. For "threshold", the numerical value is increased or decreased and input by operating "+" or "-" using selection unit 621c.

In addition, on the display screen 621a, as an item stored in the history storage unit 623 described later, a "detection value history" that displays the history of the back pressure P obtained from the digital seating sensor 613 can be displayed. In addition, on the display screen 621a, as an item stored in the history storage unit 623 described later, a "NG count" that displays the number of times an abnormal signal Sa has been obtained in the past can be displayed.

In addition, the display screen 621a can display, as an item stored in the history storage unit 623 described later, a "total number of detections," which displays the total number of times that the digital seat sensor 613 has detected the back pressure P in the past. Furthermore, the display screen 621a can display an "NG ratio," which can be calculated by dividing the "NG number of times" by the "total number of detections."

Returning to FIG. 3 again, the setting unit 622 sets each threshold LV and the reference threshold LVb input by the input unit 621 to the pressure switch 615. Here, the setting unit 622 can write each threshold LV and the reference threshold LVb as an NC program using, for example, an M code, and set the pressure switch 615.

Specifically, the setting unit 622 writes, for example, in an NC program, each threshold LV (or reference threshold LVb) between an identifiable start code and end code for each machining operation (each machining content). The setting unit 622 then sets the threshold LV and reference threshold LVb by outputting the generated NC program to the pressure switch 615. This allows the pressure switch 615 to sequentially change the threshold LV according to the machining operation for each machining operation in accordance with the NC program.

The setting unit 622 can also set all the threshold values LV and reference threshold value LVb input by the input unit 621 in a lump sum to the pressure switch 615. In this case, the pressure switch 615 can change the threshold value LV (or reference threshold value LVb) for each processing (each processing content) by, for example, referring to the processing information J acquired from the control device 47.

The history storage unit 623 sequentially stores, in an updatable manner, the back pressure P, the normal signal Sn, and the abnormal signal Sa, which are digital signals acquired from the digital seating sensor 613. The history storage unit 623 then outputs to the input unit 621 the updatable stored detection value of the back pressure P, the number of times that the back pressure P was acquired (i.e., the total number of detections), the number of times that the abnormal signal Sa was acquired, the ratio of the number of times that the abnormal signal Sa was acquired to the total number of detections, and the like.

4-3. Operation of seating determination device 60 The seating determination device 60 can set a threshold value LV for each different machining (or for each different machining content), and uses the set threshold value LV or a preset reference threshold value LVb to determine the seating state of the workpiece W on the seating portion 42b. Meanwhile, the back pressure P detected by the digital seating sensor 613 is likely to change depending on each machining in the machine tool 30, more specifically, on each machining content for the workpiece W.

Here, examples of elements (parameters) that determine different machining (or different machining contents) include the machining position, which is the position where the machining is performed on the workpiece W, the machining direction, which is the direction in which the machining is performed, the machining speed, which is the speed at which the machining is performed, and the machining amount, which is the amount of machining performed (for example, the feed amount of the tool 43a or the removal volume, etc.). Therefore, when setting a threshold value LV for each different machining, it is necessary to set it according to the tendency of change in the back pressure P corresponding to each machining content.

In the following description, as shown in Fig. 5, the position where the tool 43a processes the tip side of the workpiece W is referred to as the first processing position A1, and the position where the tool 43a processes the base end side of the workpiece W is referred to as the second processing position A2. Also, as shown in Fig. 5, the direction in which the tool 43a moves away from the seating surface 42b1 of the seating portion 42b is referred to as the first processing direction D1, and the direction in which the tool 43a approaches the seating surface 42b1 is referred to as the second processing direction D2. Also, as shown in Fig. 5, the speed at which the tool 43a processes the workpiece W is referred to as the processing speed V, and the feed amount of the tool 43a to the workpiece W is referred to as the processing amount R.

4-3-1. Cases where the machining position is different For example, assume that the workpiece W is cut in the machine tool 30. In this case, as shown in FIG. 5, when the tool 43a (e.g., a cutting tool) cuts the workpiece W at the first machining position A1, the back surface W1 is likely to be inclined relative to the seating surface 42b1. Therefore, in this case, the workpiece W is likely to be in a floating state, and the detected back pressure P is greatly reduced. For this reason, in machining (machining contents) in which the machining position is the first machining position A1, it is necessary to set the threshold value LV to a value smaller than the reference threshold value LVb, for example, in order to accurately determine the seating state of the workpiece W.

On the other hand, when the tool 43a cuts the workpiece W at the second machining position A2 on the base end side, the inclination of the back surface W1 relative to the seating surface 42b1 becomes smaller than in the case of the first machining position A1. Therefore, in this case, the workpiece W is less likely to be raised, and the decrease in the detected back pressure P is smaller. For this reason, in machining (machining content) in which the machining position is the second machining position A2, it is necessary to set the threshold value LV to a value greater than the reference threshold value LVb, for example, in order to accurately determine the seating state of the workpiece W.

4-3-2. When the machining direction is different For example, as shown in FIG. 5, when the tool 43a cuts the workpiece W along the first machining direction D1, the workpiece W is likely to move in the direction away from the seating surface 42b1 of the seating portion 42b, as shown by the dashed arrow. Therefore, in this case, the workpiece W is likely to be in a floating state, and the detected back pressure P is greatly reduced. For this reason, in machining (machining contents) in which the machining direction coincides with the first machining direction D1, it is necessary to set the threshold value LV to a value smaller than the reference threshold value LVb, for example, in order to accurately determine the seating state of the workpiece W.

On the other hand, when the tool 43a cuts the workpiece W along the second machining direction D2, the workpiece W is more likely to move in the seating direction approaching the seating surface 42b1 of the seating portion 42b, as shown by the dashed arrow. Therefore, in this case, the workpiece W is less likely to be lifted up, and the decrease in the detected back pressure P is smaller. For this reason, in machining (machining content) in which the machining direction coincides with the second machining direction D2, it is necessary to set the threshold value LV to a value greater than the reference threshold value LVb, for example, in order to accurately determine the seating state of the workpiece W.

4-3-3. When the machining speed is different For example, as shown in FIG. 5, when the tool 43a cuts the workpiece W along the first machining direction D1, the friction between the workpiece W and the tool 43a increases as the machining speed V increases, and as a result, the workpiece W is more likely to move in the lifting direction as shown by the dashed arrow. Therefore, the higher the machining speed V, the more likely the workpiece W is to be in a lifted state, and the greater the decrease in the detected back pressure P. For this reason, in the case of the first machining direction D1, the higher the machining speed V (machining content) is, the more accurately the seating state of the workpiece W is determined, so it is necessary to set the threshold value LV to a value smaller than the reference threshold value LVb, for example.

On the other hand, when the tool 43a cuts the workpiece W along the second machining direction D2, the higher the machining speed V, the easier it is for the workpiece W to move in the seating direction, as shown by the dashed arrow. Therefore, in this case, the workpiece W is less likely to float, and the decrease in the detected back pressure P is smaller. For this reason, in the case of the second machining direction, the higher the machining speed V (machining content), the more accurately it is necessary to set the threshold value LV to a value greater than the reference threshold value LVb, for example, in order to determine the seating state of the workpiece W.

4-3-4. When the machining amount is different For example, as shown in FIG. 5, when the tool 43a cuts the workpiece W along the first machining direction D1, the greater the machining amount R, the greater the friction between the workpiece W and the tool 43a, and as a result, the workpiece W is more likely to move in the lifting direction as shown by the dashed arrow. Therefore, the greater the machining amount R, the more likely the workpiece W is to be in a lifted state, and the greater the decrease in the detected back pressure P. For this reason, in the case of the first machining direction D1, the greater the machining amount R (machining content), the more accurately the seating state of the workpiece W is determined, and for example, the threshold value LV must be set to a value smaller than the reference threshold value LVb.

On the other hand, when the tool 43a cuts the workpiece W along the second machining direction D2, the greater the machining amount R, the easier it is for the workpiece W to move in the seating direction, as indicated by the dashed arrow. Therefore, in this case, the workpiece W is less likely to float, and the decrease in the detected back pressure P is smaller. For this reason, in the case of the second machining direction, the greater the machining amount R (machining content), the more it is necessary to set the threshold value LV to a value greater than the reference threshold value LVb, for example, in order to accurately determine the seating state of the workpiece W.

4-3-5. Cases where machining is different For example, assume that the cutting process shown in FIG. 5 and the hole-making process (drilling process) shown in FIG. 6 are performed on the workpiece W in the machine tool 30. In the case of hole-making, the machining direction of the tool 43a (e.g., drill bit) coincides with the second machining direction D2 in which the tool 43a approaches the seating surface 42b1, i.e., the seating direction. Therefore, when comparing the case where the machining directions of both the cutting process and the hole-making process are the second machining direction D2, the force with which the tool 43a presses the workpiece W in the seating direction is relatively larger in the case of hole-making.

That is, when the tool 43a drills holes in the workpiece W, the workpiece W is more likely to move in the seating direction than in the case of cutting, as shown by the dashed arrow in Figure 6. Therefore, in the case of drilling, the workpiece W is less likely to float compared to the case of cutting, and the decrease in the detected back pressure P is smaller. For this reason, when the machining direction is the same, in drilling, it is necessary to set a value larger than each threshold value LV that is set according to the different machining contents (parameters) of the cutting described above.

As described above, according to the tendency of the threshold LV to be set for each different processing (each different processing content), the worker operates the input unit 621 of the setting device 62 to set the threshold LV for each different processing (each different processing content). That is, on the display screen 621a of the input unit 621, the worker first selects "processing (processing content)" using the selection unit 621b. Next, the worker inputs an appropriate threshold LV for the target processing (processing content) using the selection unit 621c. In this way, the worker inputs the respective thresholds LV1, LV2, ..., LVn from "Processing No. 1" to "Processing No. n".

The input unit 621 then outputs the input thresholds LV1, LV2, ..., LVn to the setting unit 622. Here, the operator can input a reference threshold LVb that serves as a reference for all processing, for example, by using the selection unit 621c. The reference threshold LVb may be set in advance in the pressure switch 615.

The setting unit 622 acquires the thresholds LV1, LV2, ..., LVn and the reference threshold LVb from the input unit 621. Then, the setting unit 622 sets the thresholds LV1, LV2, ..., LVn and the reference threshold LVb in the pressure switch 615 for each different processing (each different processing content) or collectively.

As a result, in the detection device 61, when the workpiece W is attached to the seating surface 42b1 of the seating portion 42b of the machine tool 30, the back pressure gauge 614 starts detecting the back pressure P. In the detection device 61, the pressure switch 615 compares the back pressure P with each of the threshold values LV1, LV2, ..., LVn or the reference threshold value LVb set for each machining operation (each machining content).

If the detected back pressure P is equal to or greater than the set threshold value LV, the pressure switch 615 outputs a normal signal Sn as a digital signal to the control device 47 and the history storage unit 623. As a result, the control device 47 continues machining the workpiece W because the workpiece W is properly seated on the seating surface 42b1 of the seating portion 42b. The history storage unit 623 also stores the output normal signal Sn in an updatable manner.

On the other hand, if the detected back pressure P is less than the set threshold value LV, the pressure switch 615 outputs an abnormal signal Sa as a digital signal to the control device 47 and the history storage unit 623. As a result, the control device 47 stops machining the workpiece W because the workpiece W is in a raised state relative to the seating surface 42b1 of the seating portion 42b. The history storage unit 623 also stores the output normal signal Sn in an updatable manner.

As can be understood from the above explanation, the seating determination device 60 comprises a detection device 61 that detects the back pressure P as a physical quantity that changes depending on the seating state of the workpiece W, a pressure switch 615 as a determination unit that determines the seating state based on the back pressure P and threshold values LV1, LV2, ..., LVn set for the back pressure P in order to determine the seating state during processing of the workpiece W, and a setting unit 622 that sets the threshold values LV1, LV2, ..., LVn for each different processing of the workpiece W.

As a result, in the seating determination device 60, the threshold values LV1, LV2, ..., LVn can be set for each processing (for each processing content) by the setting unit 622. Therefore, in the seating determination device 60, the seating state, i.e., the floating state of the workpiece W, can be constantly monitored in detail for each processing (for each processing content), and as a result, the accuracy of processing the workpiece W can be improved.

In addition, the seating determination device 60 can set threshold values LV1, LV2, ..., LVn for each machining operation (each machining content). Therefore, when the seating determination device 60 is provided on the machine tool 30, the frequency of stopping machining due to an abnormality in the seating state can be reduced compared to when only one reference threshold value LVb can be set for the entire machining operation, and as a result, the productivity of the workpiece W produced by the machine tool 30 can be improved.

5. Modifications 5-1. First Modification In the above-described embodiment, the pressure switch 615 forming the digital seating sensor 613 compares the set threshold value LV with the detected back pressure P to make a judgment, and outputs an abnormality signal Sa to the control device 47 when the back pressure P is less than the threshold value LV. That is, in the above-described embodiment, the pressure switch 615 fulfills the functions of a judgment section and an output section.

Alternatively, as shown in Figures 7 and 8, the setting device 62 can compare the set threshold value LV with the detected back pressure P to make a judgment, and output an abnormality signal Sa if the back pressure P is less than the threshold value LV. The first modified example will be described below, but the same parts as in the above-mentioned embodiment are given the same reference numerals and their description will be omitted.

7, the pressure switch 615 of the digital seating sensor 613 is omitted, and the back pressure P (digital signal) detected by the back pressure gauge 614 is output to the setting device 62. In the first modified example, as shown in Fig. 8, an acquisition unit 624, a determination unit 625, and an output unit 626 are newly provided for the setting device 62. The acquisition unit 624 acquires the back pressure P (digital signal) detected by the back pressure gauge 614, and outputs the acquired back pressure P to the determination unit 625.

In the determination unit 625, the thresholds LV1, LV2, ..., LVn and the reference threshold LVb for determination are set by the setting unit 622. In this case, as in the above-mentioned embodiment, it is possible to set the threshold LV (reference threshold LVb) by describing it between the start code and the end code using the M code. The determination unit 625 compares the thresholds LV1, LV2, ..., LVn and the reference threshold LVb with the back pressure P acquired by the acquisition unit 624.

Then, the determination unit 625 outputs a normal signal Sn to the output unit 626 when the back pressure P is equal to or greater than each of the thresholds LV1, LV2, ..., LVn and the reference threshold LVb, and outputs an abnormal signal Sa to the output unit 626 when the back pressure P is less than each of the thresholds LV1, LV2, ..., LVn and the reference threshold LVb. The determination unit 625 also outputs the back pressure P acquired by the acquisition unit 624 to the output unit 626.

The output unit 626 acquires the normal signal Sn, the abnormal signal Sa, and the back pressure P output from the judgment unit 625. Then, the output unit 626 outputs the acquired normal signal Sn or abnormal signal Sa to the control device 47, and outputs the back pressure P to the history memory unit 623.

Therefore, in the first modified example, the threshold values LV1, LV2, ..., LVn can be set for each different processing (each different processing content). In the first modified example, the judgment unit 625 compares the back pressure P with each of the threshold values LV1, LV2, ..., LVn and the reference threshold value LVb to make a judgment, and a normal signal Sn or an abnormal signal Sa can be output to the control device 47 via the output unit 626. Therefore, in the first modified example, the same effect as in the above-mentioned embodiment can be obtained.

5-2. Second Modification In the above-described embodiment, the digital seating sensor 613 outputs a normal signal Sn or an abnormal signal Sa to the control device 47. Also, in the above-described first modification, the setting device 62 outputs a normal signal Sn or an abnormal signal Sa to the control device 47. When the control device 47 acquires the abnormal signal Sa, an abnormality has occurred in the seating state of the workpiece W, so that the control device 47 stops machining.

Incidentally, the control device 47 provided in the machine tool 30 has CNC, PLC, servo system, etc. as its main components, and can control the operation of the rotation drive unit 43c, tool table moving device 44, etc. according to an NC program set for each machining operation. Therefore, the control device 47 can be equipped with the setting device 62 of the above-mentioned embodiment, or the setting device 62 of the above-mentioned first modified example.

In this case, the control device 47 can be equipped with an input unit 621, a setting unit 622, and a history storage unit 623, similar to the setting device 62 in the above-mentioned embodiment. This allows the control device 47 to set a judgment threshold value LV for each processing (each processing content) in the pressure switch 615 of the digital seating sensor 613. Then, when the control device 47 acquires an abnormality signal Sa from the pressure switch 615, it is possible to stop machining because an abnormality has occurred in the seating state of the workpiece W. Therefore, in this case as well, the same effect as the above-mentioned embodiment can be obtained.

The control device 47, like the setting device 62 of the first modified example described above, can include an acquisition unit 624, a determination unit 625, and an output unit 626 in addition to the input unit 621, setting unit 622, and history storage unit 623. However, the control device 47 can omit the output unit 626 as necessary.

This allows the control device 47 to set a judgment threshold value LV for each process (each processing content) in the judgment unit 625. Then, the control device 47 compares the back pressure P acquired by the judgment unit 625 from the back pressure gauge 614 with the threshold value LV (or reference threshold value LVb) set for each different process (each different processing content) to make a judgment. If an abnormality signal Sa is acquired by the control device 47, an abnormality has occurred in the seating state of the workpiece W, and therefore the machine processing can be stopped. Therefore, in this case as well, the same effect as in the above-mentioned embodiment can be obtained.

5-3. Third Modification In the above-described embodiment, first modification, and second modification, the back pressure P, which is the pressure of the positive air supplied toward the back surface W1 of the workpiece W, is used as the physical quantity that changes according to the seating state of the workpiece W. However, the physical quantity is not limited to using the back pressure P as long as it changes according to the seating state of the workpiece W. For example, as shown in FIG. 9, the load K applied to the workpiece W by the tool 43a that performs machining, or the distance L between the workpiece W and the seating surface 42b1 can be used. Alternatively, the processing amount R per unit time (see FIG. 5) can be used.

In the above-described embodiment and each of the above-described modifications, the pressure switch 615 and the determination unit 625 as the determination unit determine the seating state of the workpiece W based on the change in the back pressure P. As described above, the back pressure P detected by the back pressure gauge 614 changes depending on the seating state of the workpiece W, that is, the floating state.

The floating state of the workpiece W changes depending on at least one of the magnitude of the processing load generated when the tool 43a performs machining on the workpiece W, the magnitude of the gripping force with which the chuck 42c grips the workpiece W during machining, and an abnormality in the tool 43a that performs machining on the workpiece W. In other words, the back pressure P changes depending on at least one of the magnitude of the processing load generated when the tool 43a performs machining on the workpiece W, the magnitude of the gripping force with which the chuck 42c grips the workpiece W during machining, and an abnormality in the tool 43a that performs machining on the workpiece W.

Therefore, the pressure switch 615 and the determination unit 625 can determine at least one of the magnitude of the processing load on the workpiece W by the tool 43a, the magnitude of the gripping force of the workpiece W by the chuck 42c, and an abnormality such as chipping or breakage of the tool 43a, based on the change in the back pressure P detected by the back pressure gauge 614. When the pressure switch 615 and the determination unit 625 determine, for example, that the processing load is greater than the reference processing load based on the change in the back pressure P during processing of the workpiece W, they can output an abnormality signal Sa.

Furthermore, when machining the workpiece W, the pressure switch 615 and the determination unit 625 can output an abnormality signal Sa if, for example, they determine that the magnitude of the gripping force is smaller than a reference gripping force based on a change in the back pressure P. Furthermore, when machining the workpiece W, the pressure switch 615 and the determination unit 625 can output an abnormality signal Sa if, for example, they determine that the magnitude of the machining amount R is smaller than a reference machining amount based on a change in the back pressure P, since there is a high possibility that an abnormality has occurred in the tool 43a. Then, in the machine tool 30, machining of the workpiece W can be stopped upon acquisition of the abnormality signal Sa.

10... Machining system, 20... Base, 30... Machine tool, 42... Headstock, 42a... Spindle, 42b... Seating portion, 42b1... Seating surface 42b1, 43a... Tool, 47... Control device, 50... Articulated robot, 60... Seating determination device, 61... Detection device, 611... Detection hole, 612... Air supply pipe, 613... Digital seating sensor, 614... Back pressure gauge, 615... Pressure switch (determination unit, output unit), 62... Setting device, 621... Input unit, 62 2...setting unit, 623...history memory unit, 624...acquisition unit, 625...determination unit, 626...output unit, LV1, LV2, ..., LVn...threshold value, LVb...reference threshold value, Sn...normal signal Sn, Sa...abnormal signal, A1...first machining position, A2...second machining position, D1...first machining direction, D2...second machining direction, V...machining speed, W...workpiece, W1...back surface, P...back pressure (physical quantity), K...load (physical quantity), L...distance (physical quantity), R...machining amount (physical quantity)

Claims (14)

A detection device that detects a physical quantity that changes depending on the seating state of the workpiece;
A determination unit provided in the detection device and configured to determine the seating state based on the physical quantity and a threshold value set for the physical quantity in order to determine the seating state during processing of the workpiece;
A setting unit that sets the threshold value in the detection device for each different machining operation performed on the workpiece;
Equipped with
The physical quantity is at least one of a back pressure, which is the pressure of positive air supplied toward the back surface of the workpiece during machining, and a distance between the workpiece and the seating surface . The seating determination device according to claim 1, further comprising an output unit that outputs an abnormality signal indicating an abnormality occurring in the seating state when the determination unit determines that an abnormality has occurred in the seating state. 3. The seating determination device according to claim 1 , wherein the detection device includes a digital seating sensor that outputs a digital signal. The seating determination device according to any one of claims 1 to 3 is provided,
A machine tool that performs machining on the workpiece seated on the seating portion. A machine tool including a seating determination device and configured to perform machining on a workpiece seated on a seating portion,
The seating determination device includes:
A detection device for detecting a physical quantity that changes depending on the seating state of the workpiece;
A determination unit that determines the seating state based on the physical amount and a threshold value set for the physical amount in order to determine the seating state during machining of the workpiece;
A setting unit that sets the threshold value for each different machining of the workpiece;
Equipped with
The physical quantity is at least one of a back pressure, which is a pressure of positive pressure air supplied toward the back surface of the workpiece during machining, and a distance between the workpiece and a seating surface,
The detection device is provided in the seating portion,
The determination unit and the setting unit are provided in a control device that inputs the physical quantity from the detection device and controls the operation of the machine tool using the input physical quantity. The machine tool according to claim 5 , wherein the determination unit compares the physical amount detected by the detection device with the threshold value set by the setting unit to determine the seating state of the workpiece on the seating portion. The machine tool according to claim 5 or 6 , wherein the control device stops machining of the workpiece when an abnormality occurs in the seating state. The machine tool according to any one of claims 4 to 7, wherein the setting unit sets the threshold value for each different machining performed on the workpiece using a tool based on at least one of the machining position, machining direction, machining speed, and machining amount relative to the workpiece . The machine tool according to claim 8, wherein the setting unit sets the threshold value to a value greater than a predetermined reference threshold value when the machining direction is a direction along a seating direction of the workpiece, and sets the threshold value to a value smaller than the reference threshold value when the machining direction is a direction along a lifting direction of the workpiece . A machine tool including a seating determination device and configured to perform machining on a workpiece seated on a seating portion,
The seating determination device includes:
A detection device for detecting a physical quantity that changes depending on the seating state of the workpiece;
A determination unit that determines the seating state based on the physical amount and a threshold value set for the physical amount in order to determine the seating state during machining of the workpiece;
A setting unit that sets the threshold value for each different machining of the workpiece;
Equipped with
The physical quantity is at least one of a back pressure, which is a pressure of positive pressure air supplied toward the back surface of the workpiece during machining, and a distance between the workpiece and a seating surface,
The setting unit sets the threshold value based on at least one of a machining position, a machining direction, a machining speed, and a machining amount for each different machining performed on the workpiece using a tool;
The setting unit sets the threshold value to a value greater than a predetermined standard threshold value when the machining direction is along the seating direction of the workpiece, and sets the threshold value to a value smaller than the standard threshold value when the machining direction is along the lifting direction of the workpiece . The machine tool according to any one of claims 4 to 10, wherein the judgment unit judges the floating state of the seating portion of the workpiece relative to the seating surface as the seating state based on back pressure, which is the pressure of positive pressure air supplied toward the back surface of the workpiece during machining, as the physical quantity. A machine tool including a seating determination device and configured to perform machining on a workpiece seated on a seating portion,
The seating determination device includes:
A detection device for detecting a physical quantity that changes depending on the seating state of the workpiece;
A determination unit that determines the seating state based on the physical amount and a threshold value set for the physical amount in order to determine the seating state during machining of the workpiece;
A setting unit that sets the threshold value for each different machining of the workpiece;
Equipped with
The determination unit determines the floating state of the workpiece at the seating portion relative to the seating surface as the seating state based on the back pressure, which is the pressure of positive air supplied toward the back surface of the workpiece during machining , as the physical quantity. The machine tool according to claim 11 or 12, wherein the pressure varies depending on at least one of the magnitude of the machining load on the workpiece, the magnitude of the gripping force that grips the workpiece during machining, and an abnormality in a tool that machines the workpiece. The machine tool according to claim 13, wherein the determination unit further determines at least one of the magnitude of the machining load, the magnitude of the gripping force, and an abnormality of the tool based on the determination of the seating state.

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