JP2002120130A - Blade tool position control method on machine tool and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of contact detection under a method to carry out moving control of a cutting tool thereafter with a contact position as a standard by detecting contact of a knife edge of the cutting tool and the standard member by using a fact that an electric circuit is closed and an electric current flows when the knife edge of the cutting tool and the standard member make contact with each other, detecting a position of a cutting tool moving device at that time. SOLUTION: A second circuit 98 furnished with a resistor 106 is provided in parallel with a first circuit 96. It is possible to confirm that a direct current electric power source 104, an electric current detector 100, etc., are normal by detecting the electric current by the electric current detector 100 as the cutting tool 48 does not make contact with the standard member 92 and the electric current from the direct current electric power source 104 flows to the second circuit 98 even in a state where the first circuit 96 is in an open state. Moving control of the cutting tool 48 thereafter is carried out with the detected position as a standard by detecting a position of the cutting tool 48 by encoders 72, 74 belonging to X driving motor 52, Y driving motor 62 to move a position of the cutting tool 48 at the time when the knife edge of the cutting tool 48 makes contact with the standard member 92.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the position of a cutting tool in a machine tool and an apparatus suitable for carrying out the method. In addition, there are a case where the cutting tool itself constitutes the entire cutting tool like a solid tool, and a case where a cutting tip or a blade as a cutting tool is detachably attached to the cutting tool main body and forms a cutting tool together with the main body. .

[0002]

2. Description of the Related Art In a machine tool, a workpiece is cut by a blade and a workpiece being relatively moved by a relative moving device, and processed into a product (including an intermediate product) having a desired shape and dimensions. Is done. At that time, if the relative position of the cutting tool to the workpiece is not properly controlled, a desired product cannot be obtained. For example, in an automatic machine tool, a moving device that moves at least one of a cutting tool and a workpiece is automatically controlled according to a predetermined program, and as a result, in order to obtain a desired product. In addition, it is necessary to accurately detect the relative position between the cutting tool and the workpiece. Therefore, conventionally, a touch probe (detector of a touch sensor) or a cutting tool is brought into contact with an object to be contacted such as a standard member or a reference portion of a machine tool, and the position of the moving device at the moment of contact (referred to as a contact position) is determined. Reading from a position detecting device and controlling the moving device based on the read contact position are performed.

The present invention is applied to a blade position control method and apparatus of a type which detects a relative position between a blade and a workpiece by bringing the blade itself into contact with a workpiece without using a touch sensor. is there. For example, when the machine tool is an automatic lathe and the processing location of the workpiece is the outer peripheral surface, the cutting tool is moved in the radial direction of the workpiece, and the cutting edge of the cutting tool contacts the contact surface of the workpiece. By doing so, the positions of the cutting edge of the cutting tool and the contact surface of the contact object coincide. Therefore, if the relative position between the contact surface and the workpiece is known, the movement of the cutting tool is controlled based on the contact position of the cutting edge with the contact surface, so that the workpiece can be accurately formed into a desired shape and shape. It can be processed into products with dimensions.

[0004] The same applies to a case where the machine tool is a machining center or the like in which a rotary cutting tool such as an end mill is used as a cutting tool. However, in the machining center, the cutting tool is rotated and all necessary movements for machining may be performed.However, both the cutting tool and the workpiece are moved. In many cases, an appropriate relative movement is obtained. In the latter case, the control of the relative movement between the cutting tool and the workpiece is performed by using a workpiece moving device that moves a workpiece holding member such as a workpiece holding table that holds the workpiece, and a cutting tool. This is performed under the control of a tool moving device that moves a tool headstock that rotatably holds a tool spindle that holds and rotates. Further, in order to remove the error of the distance between the rotation center line of the cutting tool and the cutting edge, approach the rotating tool and the contacted object while rotating the rotating tool, and when the position where both contact is detected, In some cases, the contact position is detected without rotating the cutting tool.

When a touch sensor is used, a touch sensor is required, which increases the cost of the apparatus. In addition, the relative position error between the touch sensor and the blade is included in the error in the movement control of the blade, and the control accuracy is correspondingly increased. Decrease. The above problem can be solved by detecting the contact position by bringing the blade into contact with the contacted object. However, if it is not possible to reliably detect that the blade has contacted the contacted object, the blade, the object to be contacted, or the holding member for holding the object is contacted. The device may be damaged. 2. Description of the Related Art In order to detect contact between a cutting tool and a contacted object, an electric circuit including a cutting tool, a contacted object, and a power supply in series has been conventionally used. When the blade is away from the contact object, no current flows because the electric circuit is an open circuit, but when the blade comes into contact, the electric circuit becomes a closed circuit, so that a current flows. Therefore, when the state of the power supply is detected by the detector, such as by detecting the current flowing from the power supply by the current detector, it is possible to detect the moment when the blade comes into contact with the object to be contacted, and to detect the contact position. However, if the power supply, the detector, etc. break down, or the lead wires that make up the electric circuit come off, etc., it will not be detected even though the blade tool has contacted the contacted object. That is, the blade and the contacted object may be pressed more strongly, and the damage may occur.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention detects a contact position by bringing a cutting tool into contact with an object to be contacted, and detects the cutting tool based on the contact position. When controlling the relative position between the workpiece and the workpiece, the object is to improve the reliability of detection of contact between the blade and the workpiece, and according to the present invention, the blade position of each of the following aspects A control method and a tool position control device are obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention and should not be construed as limiting the technical features and combinations thereof described in the present specification to those described in the following sections. . Further, when a plurality of items are described in one section, the plurality of items need not always be adopted together.
It is also possible to select and adopt only some of the items.

(1) In a machine tool, a cutting tool and an object to be contacted are relatively moved by a moving device capable of detecting a moving position so that they are brought into contact with each other, and a subsequent movement is performed based on the moving position of the moving device at the time of contact. A cutting tool position control method for controlling relative movement between a cutting tool and a workpiece, wherein a contact detection device that detects contact between the cutting tool and the contacted object detects a contact between the cutting tool and the workpiece. A normality checking step for confirming that it is in a detectable state, and the blade tool and the object to be contacted are brought closer to each other by the moving device after the normality checking step or while performing the normality checking step, so that the blade tool is covered. A tool position control method (claim 1), comprising: a contact detection step of detecting contact with a contact object. After confirming that the contact detection device can detect the contact between the cutting tool and the contacted object, or if the cutting tool and the contacted object are approached while confirming, the cutting tool and the contacted object are However, it is possible to prevent any one of them or the holding device holding them from being damaged due to the fact that they are not detected even though they contact with each other, and are brought closer together. When the contact between the blade and the contacted object is detected, the approach between the blade and the contacted object by the moving device is immediately stopped. The time required from this contact detection to approach stop is extremely short, and it has been confirmed by experiments that the blade tool or the contacted object is not damaged by overshoot of the tool and the object to be moved. I have. (2) In the machine tool, the cutting tool and the object to be contacted are relatively moved by a moving device capable of detecting the moving position so that they are brought into contact with each other. A cutting tool position control method for controlling relative movement with a workpiece, wherein the cutting tool, the contacted object, and a power source are connected in series, and a closed circuit is formed when the cutting tool and the contacted object are in contact with each other, and the contact is not made. A first circuit forming step of preparing a first circuit to be an open circuit; and a power supply connected to the power supply in parallel with the first circuit and at least having an electric resistance regardless of contact or non-contact between the blade and the contacted object. A second circuit forming step of preparing a second circuit forming a closed circuit including in series, and detecting the state of the power supply with a detector in a state where the first circuit is an open circuit, at least the power supply and the detection The vessel is normal And the normal confirmation process to verify that,
When the detector detects that the state of the power supply has become a state corresponding to the transition from the state of the open circuit to the state of the closed circuit of the first circuit, the moving position of the moving device is determined. A cutting tool position control method for a machine tool, comprising: a contact position reading step of reading as a contact position between the cutting tool and the contacted object (claim 2). In a state where the cutting tool is not in contact with the contacted object, the first circuit is an open circuit, so that no current flows through the first circuit and current flows only through the second circuit. On the other hand, if the blade and the contact object come into contact,
The first circuit becomes a closed circuit, and current flows through the first circuit as well as the second circuit. Since these two circuits are parallel to the power supply, the amount of current increases. When the first circuit becomes a closed circuit, in order to avoid that an excessive current flows and the power supply and the detector are damaged, the power supply itself has a current limiting device for limiting the maximum current, Alternatively, it is desirable to provide some resistance in the first circuit. Although it is possible to intentionally provide a resistor in the first circuit, it is also possible to use the resistance of the main body of the machine tool itself as the resistance of the first circuit. In any case, the difference between the current in the state where the first circuit is in the closed circuit and the current in the state where the first circuit is in the open circuit is clear.
It is desirable that the resistance of the second circuit be equal to or greater than the resistance of the first circuit, and if circumstances permit, it should be clearly higher than the resistance of the first circuit. However, even in a state where a current flows only in the second circuit, it is necessary that the fact can be clearly detected by the detector. If the power supply or the detector breaks down, or if a conductive member such as a lead wire comes off or breaks, and the current stops flowing in the second circuit, the fact is surely detected by the detector. And the contact between the blade tool and the contacted object cannot be detected. Therefore, the blade and the contacted object are brought closer to each other in a state where contact cannot be detected, and further brought closer after contact,
Breakage of the cutting tool and the like is well avoided. (3) The normality checking step detects a current flowing from the power supply, and determines a first current having a current greater than 0 and a second current having a value greater than the first current. The tool position control method according to item (2), wherein the normality is confirmed when the size is between (2). The detection of the state of the power supply can be performed in various ways. For example, when the first circuit becomes a closed circuit and the voltage between the output terminals of the power supply drops at the moment when the current suddenly increases, by detecting the voltage drop, the contact between the blade and the contacted object is detected. be able to. However, it is a simpler and more reliable method to detect a sudden increase in the current from the power supply using a current detector. (4) The contact position reading step is a step of reading a moving position of the moving device when a current flowing from the power supply exceeds a third current that is predetermined to be larger than the second current. (3) Item 6. A cutting tool position control method according to the above item. The third current is desirably set to a value larger than the current flowing in the first circuit when the cutting edge of the cutting tool and the surface of the contacted object are connected by the cutting fluid. If at least one of the cutting edge of the cutting tool and the surface of the contacted object is brought close to each other in a state of being wet by the cutting fluid, before the two come into direct contact, the first circuit is brought into a semi-closed circuit state by the cutting fluid. Since the current increases, it is desirable that the third current be set so that the contact between the cutting edge of the cutting tool and the surface of the contacted object is not detected in such a current increase. (5) In the machine tool, the cutting tool and the object to be contacted are relatively moved by a moving device capable of detecting the moving position so that they come into contact with each other. A cutting tool position control method for controlling relative movement with respect to a workpiece, wherein a resistance circuit is provided between the cutting tool and the contacted object, the connection circuit connecting the two via a first electrical resistance of a predetermined size. And a normality checking step of confirming that the electrical resistance between the cutting tool and the object to be contacted is substantially equal to the first electrical resistance in a state where the blade is not in contact with the contacted object, and performing the normality checking step. After that, or while performing the normality check step, the cutting tool and the object to be contacted are brought closer to each other by the moving device, and the electric resistance between them becomes smaller than the second electric resistance smaller than the first electric resistance. When the blade A blade position control method, which comprises a contact detection step of detecting a contact between the contacted object. (6) The tool position control method according to any one of (1) to (5), wherein the object to be contacted is a workpiece attached to the machine tool (Claim 4). (7) The cutting tool position control method according to any one of (1) to (5), wherein the contacted object is a standard member attached to the machine tool. The standard member may have a dimension substantially equal to the target dimension of the product to be currently processed, or may have a known dimension different from the target dimension of the product to be currently processed. May be common to all products. (8) The cutting tool position control method according to any one of (1) to (5), wherein the contacted object is a reference portion provided on the machine tool. (9) The cutting tool position control method according to any one of (1) to (8), wherein the cutting tool is a cutting tip fixed to a shank of a cutting tool. (10) The cutting tool position control method according to any one of (1) to (8), wherein the cutting tool is at least a part of a rotary cutting tool attached to a tool spindle of the machine tool. (11) The cutting tool position control method according to (10), wherein in the contact position reading step, the rotary cutting tool is brought into contact with the contacted object while being rotated. (12) In the second circuit, the cutting fluid and the chips are attached to both sides of the electric resistance, are electrically insulated from each other, and adhere to the two members connected by the electric resistance. A circuit that bypasses the electric resistance is formed, and even though the cutting tool and the contacted object are not in contact, the first circuit erroneously transitions from the open circuit state to the closed circuit state. Any of (2) to (4), including a step of covering at least a part of at least one surface of a member located on both sides of the electric resistance with a layer of an electrically insulating material to prevent the determination. The cutting tool position control method according to any one of the above. The technology described in this section for covering the surface of a necessary member with a layer of an electrically insulating material can be employed also in the above modes (5) to (11). (13) Despite that it is clear that the cutting tool and the contacted object are at a relative position to be contacted, when contact between the cutting tool and the contacted object is not detected, the cutting tool has a defect. Including a loss determination step to determine that there is a possibility (1)
Item 14. The method for controlling the position of a cutting tool according to any one of the above items 12 to 12. For example, at the start of the cutting of the workpiece, in the process of bringing the blade tool and the workpiece close to each other, the operation for detecting contact is continued, and it is certain that the blade tool comes into contact with the workpiece. Contact is not detected when both are brought close to the relative position but no contact is detected, or even when the operation for detecting the contact is continued during the cutting of the workpiece, the contact is not detected When the state appears, it is determined that there is a possibility that the cutting tool has been lost. The operator can check the condition of the cutting tool according to the operation of the alarm based on the determination and the display on the display, and can take necessary measures. As described above, according to the present embodiment, it is possible to easily detect the loss of the cutting edge of the cutting tool. When it is determined that there is a possibility that the cutting tool has been lost, it is desirable that the relative movement between the cutting tool and the contacted object be automatically stopped. (14) The touch probe is provided so as to be immovable relative to the blade, and a contact detection step of detecting a contact between the touch probe and the contacted object is performed. The cutting tool position control method according to claim (claim 5). If a touch probe is provided, it becomes possible to detect an impossible or inappropriate position depending on the contact of the blade. For example, in a lathe, if a touch probe having a spherical contact end is used, the contact end of the touch probe is placed at two locations separated in the diameter direction on the outer peripheral surface of the workpiece or the standard member held by the chuck. Contact can be made to detect the position of the center line of rotation of the workpiece or standard member, but it is impossible or inappropriate to use the tool in that way. If the position of the rotation center line of the workpiece or the standard member is detected and the relative position between the touch probe and the cutting tool is known, the movement control of the cutting tool can be performed based on the contact position of the touch probe. Note that it is desirable, but not essential, to perform the normality check step for the touch probe. Conversely, it is also possible to perform only the normality check process for the touch probe alone without performing the normality check process for the blade tool. (15) In the contact detecting step, the contact between the cutting tool and the contacted object is detected under a condition that can be determined as a state where the cutting tool and the contacted object are separated by the cutting fluid despite being separated from each other. The cutting tool position control method according to any one of the above modes (1) to (14). For example, in the aspect of the above item (2), the threshold value for detecting the transition of the first circuit to the closed circuit state is determined by the detection of the detector when the cutting tool and the contacted object are connected by the cutting fluid. The value is set to a value different from the value (if it is a current value, the current value is larger than the current value in a state of being connected by the cutting fluid). (16) In the machine tool, the cutting tool and the object to be contacted are relatively moved by a moving device capable of detecting the moving position so that they are brought into contact with each other. A tool position control method for controlling relative movement with respect to a workpiece, wherein the blade is in contact with a workpiece as the workpiece, and the moving device when the blade and the workpiece are just contacted. A dimension measuring step of measuring the dimension of the workpiece based on the movement position of the workpiece, and a control step of controlling the subsequent relative movement between the cutting tool and the workpiece based on the dimension of the workpiece measured in the dimension measuring step And a cutting tool position control method. A dedicated machine for measuring the dimensions of the workpiece is provided on the machine tool, the dimensions of the workpiece are measured on the machine, and the relative movement between the blade and the workpiece is determined based on the measurement results. Control is performed, and this is effective when the required accuracy of the dimensions is high. However, the measurable range of the dimension measuring device used for that purpose is usually very narrow. On the other hand, a wide range of dimensions can be accurately detected by using a blade as a contact, a blade moving device as a contact moving device, and a moving position detecting device for detecting a moving position of the blade moving device as a scale. It becomes possible. Therefore, according to the present invention, it is possible to process a workpiece having a plurality of parts having greatly different dimensions and a plurality of workpieces having greatly different dimensions with high accuracy. It should be noted that the present invention can be adopted in combination with any one of the above items (1) to (15). (17) In the machine tool, the cutting tool and the object to be contacted are relatively moved by a moving device capable of detecting the moving position so that they come into contact with each other. A cutting tool position control device that controls relative movement with a workpiece, wherein a contact detection device that detects contact between the cutting tool and the contacted object can detect a contact between the cutting tool and the contacted object if the cutting tool contacts the contacted object. A confirmation unit for confirming that the state is in a state, and after the confirmation by the confirmation unit or in a state where the confirmation is continued, the cutter and the contacted object are brought closer to the moving device, and the blade and the contacted object are And a contact detection unit for detecting that the blade has come into contact with the blade. If the present blade position control device is used, the blade position control method of the above item (1) can be favorably implemented. (18) In the machine tool, the cutting tool and the object to be contacted are relatively moved by a moving device capable of detecting the moving position so that they are brought into contact with each other. A cutting tool position control device for controlling relative movement with a workpiece, wherein the cutting tool, the contacted object, and a power supply are connected in series, and a closed circuit is formed when the cutting tool and the contacted object are in contact with each other, and no contact is made. In the first circuit to be an open circuit, connected to the power supply in parallel with the first circuit,
A second circuit for forming a closed circuit including at least an electric resistance in series regardless of whether the blade tool and the contact object are in contact with or not in contact with each other, a detector for detecting a state of the power supply, and an opening of the first circuit. When the detection result of the detector indicates that at least the detector and the power supply are normal in a circuit state, the cutting tool and the object are brought closer to the moving device, and the detection is performed. And a controller for controlling the moving device based on the moving position of the moving device at the time when the detection result of the tool indicates the contact between the cutting tool and the contacted object. (Claim 7). If the present blade position control device is used, the blade position control method of the above item (2) can be favorably implemented. (19) An insulating device that electrically insulates between the cutting tool or a cutting tool side portion which is a part in electrical conduction with the cutting tool and a main body of the machine tool, wherein the electric resistance is equal to the cutting tool side portion. The cutting tool position control device according to the mode (18), disposed between the cutting tool position and the main body of the machine (Claim 8). The “main part of the machine tool” is a part that includes not only the main body frame but also all members that are in electrical communication with the main body frame. That is, the portion closer to the main body frame than the insulating device is the main body portion. This is the same in the next section. (20) The workpiece holding member itself that holds the workpiece of the machine tool, or the workpiece holding member side portion that is a portion that is in electrical conduction with the workpiece holding member, and the main body of the machine tool And a cutting tool position control device according to (18), wherein the electrical resistance is disposed between the workpiece holding member side portion and the main body of the machine tool. (Claim 9). (21) The cutting tool position control device according to any one of (18) to (20), wherein the electric resistance is formed of a resistance layer sandwiched between conductors. Each component of a tool holding member, a cutting tool holding member, a workpiece holding member, a main body, and the like of a machine tool is generally formed of a good electrical conductor such as steel or brass. The second circuit can be easily configured by providing the second circuit between them. However, it is necessary that the fixing device for fixing the members on both sides of the resistance layer to each other can fix both members while preventing electrical conduction between the members on both sides. If the resistance layer also has a function of fixing the members on both sides to each other, a fixing device is not required. (22) The cutting tool position control device according to any one of (18) to (20), wherein the electric resistance is a fixed resistor provided with a pair of terminals at both ends of an electric resistor. The resistance layer described in the previous section comes in contact with the members on both sides in a large area, and since the resistance value varies depending on the contact area, it is relatively difficult to accurately obtain the desired resistance value. Thus, it is easy to obtain a desired resistance value. (23) The item (18), (19) or (22) wherein the electric resistance is incorporated in at least one of a cutting tool provided with the cutting tool and a tool holding member for holding the cutting tool. A cutting tool position control device as described in the above. When the cutting tool is fixed to the cutting tool main body, the cutting tool includes the cutting tool and the cutting tool main body. For example, it is more natural to consider that the entire cutting tool is integral and the whole is the cutting tool. What is called a solid tool means that the cutting tool has only a cutting tool. A blade tool such as a welding tool, a brazing tool, or the like, in which the blade tool is irremovably fixed to the cutting tool body, can be considered to be a cutting tool including the blade tool and the cutting tool body. For convenience, it is assumed that the entire cutting tool is a cutting tool, similar to a solid tool. Therefore, a cutting tool including a cutting tool and a cutting tool main body means a cutting tip or a blade is detachably fixed to the cutting tool main body by a clamp device, and constitutes a cutting tool in cooperation with the cutting tool main body. Will be. (24) The electric resistance is a fixed resistor incorporated in one of a workpiece holding member for holding the workpiece and one of the constituent members of the main body of the machine tool. (20) 3. The cutting tool position control device according to claim 1. (25) an insulating device that electrically insulates the cutting tool from the main body of the machine tool, a first conductive path having one end connected to the cutting tool side of the insulating device and the other end connected to the power supply; A second conductive path that connects to the main body of the machine tool, and a current detector as the detector that detects a current flowing through the first circuit including the first conductive path and the second conductive path,
A third conductive path as the second circuit connecting the cutting tool side of the insulating device and the main body of the machine tool via the electrical resistance, wherein the third conductive path is at least shorter than the first conductive path
The cutting tool position control device according to any one of the modes (18) to (23). If the power supply is arranged near the cutting tool, the first conductive member can be shortened, and the possibility of the first conductive member coming off or being damaged can be reduced. Power supply or detector is easily damaged by the influence of cutting fluid or chips, so the power supply must be installed at a position away from the cutting tool in many cases. In that case, the first conductive path must be lengthened. On the other hand, since the electrical resistance is relatively insensitive to cutting fluid and chips, the third conductive path can be easily shortened. If the third conductive path is damaged or detached, the control device determines that the power supply and the like are not normal even though the power supply, the detector, the first conductive path, and the like are normal, and notifies the mobile device of the failure. It is desirable that the third conductive path be as short as possible so as to reduce the possibility of breakage or detachment so that the blade and the contact object do not approach each other. (26) The electric resistance is a fixed resistor provided with a pair of terminals at both ends of an electric resistor, and the third conductive path holds the cutting tool provided with the cutting tool together with the fixed resistor and the cutting tool. Built in either one of the tool holding members
The cutting tool position control device according to the above mode (25). If the third conductive path as well as the electrical resistance is incorporated in either the cutting tool or the tool holding member, the third conductive path is also protected by one of them, so it can be damaged or come off. Can be satisfactorily avoided. The same applies to the next term. (27) The electric resistance is a fixed resistor provided with a pair of terminals at both ends of an electric resistor, and the third conductive path is formed between the work holding member and the main body of the machine tool together with the fixed resistor. Built into one of the components
The cutting tool position control device according to the above mode (25). (28) In the second circuit, at least a portion of the surface of at least one of the members located on both sides of the electric resistance, which is adjacent to the surface of the other member, is covered with a layer of an electrically insulating material. The cutting tool position control device according to any one of claims to (27) (Claim 10). (29) a touch probe immovable relative to the blade tool;
The touch probe, the contacted object, and the power supply are connected in series, and the switching circuit includes a closed circuit when the touch probe and the contacted object are in contact with each other and an open circuit when the touch probe is not in contact with each other. 28) The cutting tool position control device according to any one of the above items. At least one of the contacted object and the power supply may be separate from or common to the contacted object and the power supply of the first circuit. Further, the configuration of this section can be adopted separately from the configuration described in section (18). However, the "moving device for relatively moving the touch probe and the cutting tool and the object to be contacted", "connected to a power source in parallel with the first circuit as the opening / closing circuit, and the contact and non-contact between the touch probe and the object to be contacted. Regardless of the second circuit that forms a closed circuit that includes at least the electrical resistance in series "," the detector that detects the state of the power supply "
And `` When the detection result of the detector indicates that at least the detector and the power supply are normal in the state where the first circuit is open circuit, the touch probe and the contact object are brought closer to the moving device. It is effective to provide a control device for controlling the subsequent moving device based on the moving position of the moving device at the time when the detection result of the detector indicates the contact between the touch probe and the contacted object ". It is. (30) The control device determines the contact between the cutting tool and the contacted object with the detection result of the detector in a state where the cutting tool and the contacted object are separated by a cutting fluid despite being separated from each other. The cutting tool position control device according to any one of the above items (18) to (29), wherein the device is detected according to a possible detection result (claim 11). (31) If the controller does not detect contact between the cutting tool and the contacted object even though it is clear that the cutting tool and the contacted object are at a relative position to be brought into contact with the cutting tool, The blade tool position control device according to any one of (18) to (30), further including a loss determination unit that determines that there is a possibility that a loss has occurred in the blade (claim 12).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an example in which the present invention is applied to a tool position control device for an automatic lathe. In FIG. 1, reference numeral 10 denotes a main body frame as an apparatus main body of the automatic lathe. Body frame 10
Is provided with a base 12, a column 14 rising upward from the base 12, a bed 16 and a headstock 18 fixed to an intermediate portion of the column 14. The headstock 18 holds the spindle 22 so as to be rotatable about a horizontal rotation center line and immovable in the axial direction. A tailstock 24 is provided on the bed 16 so as to be able to approach and separate from the headstock 18. ing. The tailstock 24 holds the center 26 in a state of being coaxially opposed to the main shaft 22. A three-jaw chuck 28 (hereinafter simply referred to as a chuck 28) as a workpiece holder is attached to the spindle 22, and the workpiece 32
Is rotated by holding both ends thereof by the chuck 28 or the center 26 of the tailstock 24 and the center (not shown) attached to the chuck 28 or the chuck 28 instead.

On the upper part of the column 14, an X guide 36 is provided.
The X guide 36 is fixed in a posture extending in the X-axis direction parallel to the rotation center line of the main shaft 22.
Are movably held in the X-axis direction. On the X slide 38, a Y guide 42 is provided so as to extend in the Y axis direction perpendicular to the rotation center line of the main shaft 22, and the Y guide 42 holds the Y slide 44 movably in the Y axis direction. ing. A tool rest 46, which is a kind of tool holding member, is fixed to the Y slide 44, and a cutting tool 48, which is a kind of cutting tool, is attached to the tool rest 46. The X slide 38 is moved by an X moving device 56 having an X drive motor 52 and a feed screw 54, and the Y slide 44 is moved on the X slide 38 by a Y drive motor 62.
The tool post 46 and the cutting tool 48 attached thereto are moved in both the X-axis and the Y-axis directions by being moved by the Y moving device 66 provided with the feed screw 64.

X drive motor 52 and Y drive motor 62
Are servomotors that can be numerically controlled, and the drive motors 52 and 62 are provided with encoders 72 and 74, respectively. The encoders 72 and 74 are connected to a control device 78 as shown in FIG.
Are the moving positions of the X moving device 56 and the Y moving device 66 based on the output signals of the encoders 72 and 74, that is,
The position of the tool rest 46 or the cutting tool 48 is calculated. The automatic lathe is an example of a machine tool having a control axis having a scale. The control device 78 is mainly composed of a computer 80, a drive circuit for driving the X drive motor 52, the Y drive motor 62, and the like, and a conversion for converting a detection signal supplied from the outside into digital data that can be input to the computer 80. It has a circuit and the like. Computer 80 is a RO
M (read only memory) 82, RAM (random access memory) 84, PU (processing unit) 86
And an I / O port 88, and a ROM 82 stores a program for processing the workpiece 32.

The control device 78 is connected to a contact detection circuit 94 for detecting the contact of the cutting tool 48 with the standard member 92. The contact detection circuit 94 includes a first circuit 96, a second circuit 98, and a current detector 100. The first circuit 96 connects the cutting tool 48 as a cutting tool, the standard member 92 as an object to be contacted, and the DC power supply 104 as a power supply in series, and closes the circuit when the cutting tool 48 and the standard member 92 are in contact with each other. The circuit is an open circuit when no contact is made. The standard member 92 is a member having a dimension substantially equal to a target dimension (specifically, a target diameter) of a product processed from the workpiece 32, and is attached to the chuck 28 instead of the workpiece 32. The second circuit 98 is
This circuit is connected to the DC power supply 104 in parallel with the first circuit 96 and forms a closed circuit including at least the resistor 106 in series regardless of whether the cutting tool 48 is in contact with the standard member 92 or not. The current detector 100 is a type of a detector that detects the state of the DC power supply 104, and detects a current flowing from the DC power supply 104 to the first circuit 96 and the second circuit 98.

As shown in FIG. 2, the cutting tool 48 is mounted on a shank 110 as a cutting tool body.
Are fixed by a fixing device (not shown), and the resistor 106 is disposed between the cutting tip 112 and the main body of the automatic lathe. Specifically, as shown in FIG. 3, it is disposed between the shank 110 and the tool rest 46. The resistor 106 is a fixed resistor in which a pair of terminals 116 and 118 are provided at both ends of an electric resistor 114, and a compression coil spring 124, which is a kind of an elastic member, is accommodated in a housing recess 122 formed in the tool rest 46. (Hereinafter, simply referred to as a spring 124).

The resistor 106 and the spring 124 are accommodated movably in the axial direction in a housing 128 made of an electrically insulating material.
By being press-fitted into the housing 22, it is held in the housing recess 122. In the illustrated example, the housing recess 122 is formed as a hole with a bottom, and the housing 128 is a cylindrical member having generally open both ends. A radially inward flange 130 is provided at one opening end of the tubular member, and the housing recessed portion is oriented such that the opening end on the side where the flange 130 is provided is the opening end side of the housing recess 122. 122. In this state, the spring 124 is compressed and urges the resistor 106 toward the flange 130. A protrusion 132 projects from the center of one terminal 116 of the resistor 106. The protrusion 132 has a length that protrudes outward from the flange 130 when the resistor 106 is in contact with the flange 130. Have.

Both the shank 110 and the cutting tip 112 of the cutting tool 48 and the tool rest 46 are made of an electric conductor, but the shank 110 and the tool rest 46 are insulated by an electric insulator. In the illustrated example, the shank 110 of the tool post 46 is used.
An insulating layer 138 is formed on a surface that contacts the shank 110, and a pad 144 having an insulating layer 142 formed on one surface is provided between a bolt 140 serving as a fixing device for fixing the shank 110 to the tool rest 46 and the shank 110. It is arranged. When the cutting tool 48 is fixed to the tool rest 46, the shank 110 is connected to the projection 1 of the resistor 106.
32, the resistor 106 is pushed into the recess 122 against the urging force of the spring 124,
The shank 110, the resistor 106, the spring 124, and the tool rest 46 are pressed against each other. Therefore, when the cutting tool 48 is fixed to the tool rest 46, the cutting tool 48 and the tool rest 46 are electrically connected by a series circuit of the resistor 106 and the spring 124. Note that the insulating layer 138 can be formed by, for example, thermal spraying of an electrical insulating material such as ceramics, a PVD (physical vapor deposition) method, a CVD (chemical vapor deposition) method, or the like.

The tool rest 46 is further provided with a connecting portion 150 for connecting the cutting tool 48 to the DC power supply 104 while electrically insulating the tool 48 from the tool rest 46. Connection part 1
Reference numeral 50 includes a terminal 154 fixed to the tool rest 46 in an insulated state by an electric insulator 152, and a conduction securing section 156 for securing conduction between the terminal 154 and the shank 110 of the cutting tool 48. The conduction securing portion 156 includes a housing 160 made of an electrically insulating material, a contact 162, and a spring 164. The elastic force of the spring 164 causes the shank 110, the contact 162, and the spring 164.
And the terminals 154 are pressed against each other to ensure conduction. A lead wire 166 is connected to the terminal 154, and this lead wire 166 is connected to one terminal of the DC power supply 104 via the current detector 100 as shown in FIG.
Another terminal of the DC power supply 104 is connected to another component of the main body of the automatic lathe, for example, the main body frame 10 by another lead wire 168.

As is apparent from the above description, in the present embodiment, the insulating layer 138, 142 constitutes an insulating device for electrically insulating the cutting tip 112 as a cutting tool from the main body of the automatic lathe. I have. The contact 162, the spring 164, the lead wire 166, and the like constitute a first conductive path having one end connected to the blade side of the insulating device and the other end connected to a DC power supply.
8 constitutes a second conductive path for connecting the DC power supply 104 to the main body of the automatic lathe. The spring 124 forms a third conductive path that connects the blade side of the insulating device and the main body of the automatic lathe through the resistor 106. The spring 124, which is the third conductive path, is very short in comparison with the first conductive path including the contact 162, the spring 164, the lead wire 166, and the like, and has a small resistance.
6 are built in a tool rest 46 as a tool holding member, and both ends are connected to a resistor 106 by its own elastic force.
And is elastically pressed against the tool rest 46,
There is little risk that electrical continuity will be impaired.

The contact detection circuit 94 configured as described above
In the automatic lathe provided with, processing of the workpiece 32 is performed as follows. First, a tool 48 is attached to the tool post 46.
However, a standard member 92 is attached to the chuck 28, respectively. Thereby, the cutting tool 48, the current detector 10
0, a DC power supply 104, a first circuit 96 for connecting the main body of the automatic lathe and the standard member 92 in series, and a cutting tool 48, a DC power supply 104, a second circuit 98 for connecting the main body of the automatic lathe and the resistor 106 in series. Is formed. FIG.
_The resistance represented by ₁ represents the resistor 106 and the resistance of the portion including the tool rest 46 of the main body of the automatic lathe, but since the resistance of the main body is small, the resistance 106 is substantially expressed. You can think about it. The resistance value of the resistor 106 is desirably selected from a range of 50Ω or more and less than 500Ω in relation to a resistance value of a cutting fluid described later and a resistance value of a main body of the automatic lathe. Is set. The resistance represented by the symbol R ₂ represents the resistance of the portion including the main spindle 22 of the main body of the automatic lathe, in the present embodiment has a below 1 [Omega. Resistance values R ₁ and R _{2 of} both resistors
The relationship of R ₁ ≫R ₂ holds between them.

Initially, the cutting edge of the cutting tool 48, that is, the tip of the cutting tip 112 is at a position away from the standard member 92, in which state the first circuit 96 is in an open circuit state.
Therefore, in the related art, no current flows from the DC power supply 104, but in the present embodiment, even if the cutting edge of the cutting tool 48 is separated from the standard member 92, the second circuit 98 is in a closed circuit state. Therefore, a weak current flows.
This current is detected by the current detector 100, the detection value of the current due to the large resistance value of the resistor R ₁ is small. However, the magnitude is clearly larger than 0 and is between a predetermined first current and a second current larger than the first current. The computer 80 of the control device 78 reads the detected value of the current by executing the program, and if the read value is between the first current and the second current, the touch detection circuit 94 However, if a voltage is applied between the cutting edge of the cutting tool 48 and the standard member 92 and they come into contact with each other, it is determined that the state is in a normal state where it can be detected.
This process is a normality check process.
In the step 0, when the normality cannot be confirmed in this step, the movement control for bringing the cutting tool 48 close to the standard member 92 is not performed. Therefore, even though the cutting edge of the cutting tool 48 contacts the standard member 92, the fact is not detected, and the movement of the cutting tool 48 is continued, and the cutting tool 4
8. The occurrence of a situation in which the standard members 92 and their holding devices are damaged is satisfactorily avoided, and a highly reliable contact detection circuit 94 is provided.
Is obtained.

If normality is confirmed in the normality confirmation step,
The computer 80 controls the drive motors 52 and 62 of the X moving device 56 and the Y moving device 66 by executing the program, and causes the cutting tool 48 to approach the outer peripheral surface of the standard member 92 from the radial direction of the standard member 92. Byte 48 is
While being moved away from the standard member 92 at high speed, it is decelerated when it reaches a preset deceleration position near the standard member 92, and thereafter is brought close to the standard member 92 at low speed. This approach is desirably performed by moving the cutting tool 48 only in the radial direction of the standard member 92, that is, by moving only the Y-axis direction.

Eventually, the cutting edge of the cutting tool 48 becomes a standard member 92.
Contact the outer peripheral surface of the
The cutting edge of the cutting tool 48 and the standard member 92 may be connected by the cutting fluid. For example, if the cutting tool 48 is brought close to the standard member 92 while the cutting edge is wet with the cutting fluid, the cutting fluid contacts before the cutting edge contacts the standard member 92, and the cutting fluid has conductivity. Therefore, the cutting edge of the cutting tool 48 and the standard member 92 are electrically connected by the cutting fluid. Therefore, the first circuit 96 is in a semi-closed state, and the DC power supply 100
, The current flows through both the first circuit 96 and the second circuit 98, and the current detection value of the current detector 100 increases. However, although the electrical resistance of the cutting fluid varies depending on the contained components, it does not become smaller than 500Ω in the present embodiment, and the increase in the current detection value by the current detector 100 is relatively small. Therefore, the detected value of the current does not exceed the third current set to a value larger than the second current, and the computer 80 detects that the cutting edge of the cutting tool 48 has contacted the outer peripheral surface of the standard member 92. There is no.

On the other hand, when the cutting edge of the cutting tool 48 comes into direct contact with the outer peripheral surface of the standard member 92, the first circuit 96 becomes a closed circuit. As a result, a current flows from the DC power supply 100 through both the first circuit 96 and the second circuit 98, and the value of the current detected by the current detector 100 increases. Particularly, in the present embodiment, the resistance value of the resistor R ₂ is because it is very small compared to the resistance value of the resistor R _1, the detection value of the current value sharply increases. If the computer 80 detects that the detected value exceeds the third current with the rapid increase of the current, it determines that the cutting edge of the cutting tool 48 has contacted the outer peripheral surface of the standard member 92.

The computer 80 detects the contact between the cutting tool 48 and the standard member 92 and detects the Y movement 66 (X
The moving device 56 is also stopped (if the moving device 56 is also moved), and the encoder 74 at that time is stopped.
Based on the output signal of (72), the position of the cutting edge of the cutting tool 48 (the position in the Y-axis direction) is calculated, and the RAM is used as the contact position.
84 is stored in the contact position memory. This step is a contact position reading step. This step is performed at a predetermined time, such as when the operator is to be replaced, when the automatic lathe is first operated in the morning, or after the tool 48 or the cutting tip 112 is replaced. This is executed before the start of machining the first workpiece 32 or the like. In order to eliminate the influence of abrasion of the cutting tip 112 and expansion and contraction caused by a temperature change of the main body of the automatic lathe, the processing may be executed at predetermined time intervals or at every processing number.

Based on the contact position where the cutting edge of the cutting tool 48 contacts the standard member 92 and the known radius of the standard member 92, the position of the rotation center line of the main shaft 22 is calculated, and the position of the rotation center line is calculated. RAM 84 as a reference position in the Y-axis direction
May be stored in the reference position memory. If necessary, the cutting tool 48 is moved in the axial direction of the standard member 92, and the contact position of the standard member 92 with the end face is
It may be detected as a reference position in the X-axis direction.

Thereafter, the computer 80 corrects a portion related to the movement control of the byte 48 of the program stored in the ROM 82 based on the data of the contact position. Therefore, if the workpiece 32 is attached to the chuck 28 instead of the standard member 92 and the movement of the cutting tool 48 is controlled in accordance with the above-mentioned modified program, the workpiece 3
2 is processed into a product with high dimensional accuracy. Even if there is some error in the center height of the cutting edge of the cutting tool 48, the same cutting tool 48 is brought into contact with the standard member 92 to correct the movement control data. Never. When the touch sensor is used to correct the movement control data, if there is a difference in the center height between the touch sensor and the cutting edge of the cutting tool 48, the difference will contribute to the dimensional error of the product. According to the present embodiment, the inconvenience can be avoided.

The computer 80 continues to read the detection value of the current detector 100 while the cutting tool 48 is approached to the work 32 at the start of cutting the work 32, and the cutting tool 48 If the detected current value does not exceed the third current even though it has been moved to a position where it is certain that the cutting tip 112 will be in contact with the cutting tool 112, it is possible that the cutting tip 112 of the cutting tool 48 may be defective. Judge,
The approach of the cutting tool 48 to the workpiece 32 by the X moving device 56 and the Y moving device 66 is stopped, and an alarm device such as a buzzer or an alarm lamp is operated. Also, the workpiece 32
The reading of the detection value of the current detector 100 is continued even after the cutting process of the cutting tool is started. If the detection value decreases to the fourth current or less during the cutting process, the cutting tip 11
X moving device 5
The cutting tool is interrupted by separating the cutting tool 48 from the workpiece 32 by the 6 and the Y moving device 66, and a buzzer and an alarm lamp are operated. The fourth current is set to be larger than the magnitude of the current flowing when the cutting tool 48 and the workpiece 32 are connected by the cutting fluid. In any of the above cases, the operator checks the status of the cutting tool 48 or the like in response to the alarm of the alarm and takes necessary measures. As described above, in the present embodiment, the loss of the cutting edge of the cutting tool 48 can be easily detected.

As is apparent from the above description, the portion of the control device 78 for detecting the contact position of the cutting edge of the cutting tool 48 with the standard member 92 is described in claim 6 in which "the first circuit is an open circuit." When the detection result of the detector indicates that at least the detector and the power supply are normal in the state, the tool and the contacted object are brought closer to the moving device, and the detection result of the detector indicates that the blade and the contacted object are It is apparent that the control device performs control of the subsequent moving device based on the moving position of the moving device at the time point when the result indicates the contact.

Further, the first circuit 96 and the current detector 100 constitute a contact detecting device, and the portion of the control device 78 for executing the normality checking step cooperates with the second circuit 98 to determine that the contact detecting device is And a confirmation unit that confirms that the blade tool is in a state where it can be detected if it comes into contact with the contact object. Further, the portion of the control device 78 that performs the contact detection step constitutes a "contact detection unit that makes the blade and the contacted object approach the moving device and detects that the blade has contacted the contacted object.

In the above embodiment, the electric resistor 11
Although a resistor 106 having terminals 116 provided at both ends of 4 is used, a resistor layer 170 conceptually shown in FIG. 5 can be used instead of the resistor 106. In the illustrated example, the resistance layer 170 is sandwiched between the cutting tool 172 and the tool rest 174, both of which are conductors (good electrical conductors). The resistance layer 170 may be formed by being fixed to one surface of either the cutting tool 172 or the tool rest 174, or may be formed by independently forming a sheet between the cutting tool 172 and the tool rest 174. Good. In any case, the cutting tool 17
2 and the tool rest 174 need to be fixed to each other with the resistance layer 170 interposed therebetween, and a fixing device for that purpose does not electrically connect the cutting tool 172 and the tool rest 174. It is necessary.

As the resistance layer 170, for example, a layer obtained by mixing a good conductor powder such as a metal powder into an electrically insulating material such as a synthetic resin or ceramics can be adopted. The formation of the resistance layer 170 on the surface of the conductor can be performed by, for example, thermal spraying, coating, PVD, CVD, or the like. The PVD method requires a lower conductor temperature at the time of implementation than the CVD method. Therefore, when forming a resistive layer on the surface of a conductor whose hardness is desirably high, such as a member for holding a cutting tool or a tool holder, Is preferably a PVD method.

In the above embodiment, the cutting edge of the cutting tool 48 is brought into contact with the outer peripheral surface of the standard member 92 held by the chuck 28. However, as shown in FIG. The cutting edge of the cutting tool 172 can be brought into contact with the outer peripheral surface of the workpiece 32 itself. For example, if the diameter of the workpiece 32 is known by being measured in advance or the like, the workpiece 32
After detecting the contact position by bringing the cutting edge of the cutting tool 48 into contact with the outer peripheral surface of the cutting tool 48, the cutting tool 4 is moved from the contact position by an amount determined based on the diameter of the workpiece 32 and the target product diameter.
If cutting is performed in a state where 8 is cut, a product having desired dimensions can be obtained.

When a plurality of workpieces 32 are machined, the control data of the cutting tool 48 is corrected based on the contact position obtained as described above, and cutting is performed using the corrected control data. However, as a result of measuring the obtained product, if the dimensions of the product are within a range that does not require correction, cutting with the same control data is continued. On the other hand, if the dimensions of the product are within the range requiring correction, the control data is corrected based on the deviation from the target dimensions, and subsequent cutting is performed using the corrected control data.

Further, as shown in FIG.
If the touch probe 180 is attached together with the cutting tool 48, and the contact position detection circuit 94 is provided for the touch probe 180, the touch probe 180 is moved in the diameter direction of the outer peripheral surface of the standard member 92 (or the workpiece 32). The contact position is determined by contacting the two separated positions, and the rotational center line position of the standard member 92, that is, the rotational center line position of the main shaft 22, can be calculated as an average value of the two contact positions. In order to use the data of the rotation center line position for the movement control of the cutting tool 48, it is necessary to obtain the relative position between the touch probe 180 and the cutting edge of the cutting tool 48.
This relative position is, for example, to bring the touch probe 180 and the cutting edge of the cutting tool 48 into contact with the same portion of the standard member 92,
It can be obtained by calculation based on the moving distance of the tool rest 46 during that time.

Furthermore, the surface of the cutting tool, cutting tool, cutting tool holding member, etc. can be covered with an insulating film. For example, as shown in FIG.
Is covered with an insulating film 181. However, it is necessary to prevent the insulating film 181 from being formed on the surface of the shank 110 that is in contact with the cutting tip 112 and on the portion of the resistor 106 that is to be in contact with the terminal 116 and the contact 162. Thus, the shank 110
Is covered with the insulating film 181, the cutting fluid or chips attached to the surfaces of the shank 110 and the tool rest 46 cause resistance between the tool 48 (strictly speaking, the shank 110) and the tool rest 46 to be close to each other. Is electrically connected by bypassing the vessel 106 so that the first circuit 96 is almost closed,
Tool 48 (strictly, cutting tip 112) is a standard member 9
2 (or the workpiece 32) can be satisfactorily avoided from being erroneously detected as being in contact with the workpiece 2 (or the workpiece 32).

Before the contact detection step is performed, the cutting fluid or the cutting fluid adhering to the surface of the cutting tool, cutting tool, cutting tool holding member, workpiece, standard member, workpiece holding member, reference portion, etc. It is desirable to provide a cleaning step for removing chips by air blow or the like. By performing this cleaning step, it is also possible to avoid occurrence of erroneous detection that the cutting tip 112 has come into contact with the standard member 92 (or the workpiece 32). Of course, it is also possible to perform both the cleaning step and the formation of the insulating film, so that erroneous detection can be avoided more favorably.

In the above embodiment, the cutting edge of the cutting tool 48 is brought into contact with the standard member 92 held by the chuck 28. However, as shown in FIG. You may make it contact. In this case, the main body 178 forms a reference portion as a contacted object. Further, as shown in FIG. 9, a reference portion 184 fixedly provided on a main body frame 182 such as a machining center, a milling machine, a boring machine or the like can be used as an object to be contacted. The reference unit 184
It is preferable to have three reference planes 186, 188, and 190 formed at right angles to the three axes of the axis, the Y axis, and the Z axis. The cutting edge of the rotary cutting tool 192 as a kind of the cutting tool is brought into contact with any of the reference surfaces,
It is effective to use the contact position as a reference position of the rotary cutting tool 192 in each of the X-axis, Y-axis, and Z-axis directions.

The rotary cutting tool 192 may be brought into contact with the reference surfaces 186, 188, and 190 in a non-rotated state, or may be brought into contact while being rotated. In the latter case, when there are a plurality of cutting edges of the rotary cutting tool 192 and the distances from the rotation center line to the plurality of cutting edges are slightly different from each other,
The position at which the blade edge having the largest distance contacts the reference surfaces 186, 188, 190 is determined by using the rotary cutting tool 192 and the reference surfaces 186, 1
88, 190. 193
Is a workpiece.

FIG. 9 shows another example in which a resistance is provided between the cutting tool and the main body of the machine tool.
In the illustrated example, the resistance layer 19 is provided between a tool holder 194 as a tool holding member for holding a rotary cutting tool 192 as a cutting tool and a tool spindle 196 to which it is attached.
8 are provided. Specifically, the resistance layer 198 is formed on the inner peripheral surface of the tapered hole 200 which is a tool holding hole of the tool spindle 196.
Is coated. Also in this case, it is necessary that the fixing device that detachably fixes the tool holder 194 to the rotary spindle 196 does not electrically connect the tool holder 194 and the rotary spindle 196.

In the above-described embodiment, the resistance is provided between the cutting tool and the main body of the machine tool.
As shown in the figure, the workpiece holding member for holding the workpiece may be provided between the main body and the workpiece holding member. In the illustrated example, the jig 212 to which the workpiece 210 is attached and the main body frame 21
4 is a resistor.
Further, as shown in FIG. 11, a resistor 226 can be provided between a work table 220 that is moved by a moving device with respect to the main body frame and a jig 224 to which a workpiece 222 is attached. The way of providing the resistor 226 can be the same as, for example, the embodiment of FIG.

Although several embodiments of the present invention have been described in detail above, these are merely examples, and the present invention is not limited to the above-mentioned [Problems to be Solved by the Invention, Means for Solving Problems and Effects]. The present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, including the described embodiment.

[Brief description of the drawings]

FIG. 1 is a front view showing an automatic lathe provided with a tool position control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the cutting tool position control device.

FIG. 3 is a sectional view showing a part of the blade position control device.

FIG. 4 is a sectional view showing another part of the cutting tool position control device.

FIG. 5 is a block diagram showing a cutting tool position control device according to another embodiment of the present invention.

FIG. 6 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

FIG. 7 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

FIG. 8 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

FIG. 9 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

FIG. 10 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

FIG. 11 is a block diagram showing a cutting tool position control device according to still another embodiment of the present invention.

[Explanation of symbols]

10: body frame 52: X moving device 66: Y
Moving device 72, 74: Encoder 78: Control device 92: Standard member 92 92: Contact detection circuit
96: First circuit 98: Second circuit 100: Current detector 104: DC power supply 106: Resistor 11
0: Shank 112: Cutting tip 124: Compression coil spring 138, 142: Insulation layer 150: Connection part 166: Lead wire 170: Resistance layer 172: Cutting tool 174: Tool post 178: Main body of chuck
184: reference part 192: rotary cutting tool 194: tool holder 196: tool spindle 198:
Resistance layer 212: jig 214: body frame
216: resistance layer 220: work table 224: jig 226: resistor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hajime Mizutani 26, Hirako Yoshiwara-cho, Toyota City, Aichi Prefecture Inside Fuji Seiko Co., Ltd. (72) Inventor Eiji Goto 26, Hirako Yoshiwara-cho, Toyota-shi, Aichi Prefecture Inside Fuji Seiko Co., Ltd. 3-2, Shobo-cho, Chigusa-ku, Nagoya-shi, Aichi F-term (reference) 3C029 AA06 AA16 AA21 3C045 HA06

Claims (12)

[Claims] In a machine tool, a cutting tool and a contacted object are relatively moved by a moving device capable of detecting a moving position so that they are brought into contact with each other, and a subsequent cutting tool is determined based on a moving position of the moving device at the time of contact. A blade position control method for controlling relative movement between the blade and the workpiece, wherein a contact detection device that detects contact between the blade and the workpiece detects the contact between the blade and the workpiece when the blade contacts the workpiece. A normal checking step for confirming that the cutting tool is in a state in which the cutting tool can be brought into contact with the blade by the moving device after the normal checking step or while performing the normal checking step. A contact detection step of detecting contact with an object. 2. In a machine tool, a cutting tool and a contacted object are relatively moved by a moving device capable of detecting a moving position, and both are brought into contact with each other, and a subsequent cutting tool is determined based on a moving position of the moving device at the time of contact. And a blade position control method for controlling the relative movement between the workpiece and the workpiece, wherein the blade and the workpiece are connected in series with a power supply, and the blade and the workpiece come into contact with each other to form a closed circuit. A first circuit forming step of preparing a first circuit that is open when not in contact with the power supply in parallel with the first circuit, regardless of whether the blade is in contact with the object or not. A second circuit forming step of preparing a second circuit forming a closed circuit including an electric resistor in series, and detecting a state of the power supply with a detector in a state where the first circuit is an open circuit; And detector A normality check step of checking that the power supply is normal, and that the detector is in a state in which the state of the power supply corresponds to a transition from the open circuit state of the first circuit to the closed circuit state. A contact position reading step of reading a moving position of the moving device as a contact position between the cutting tool and the contacted object when detecting the position of the cutting tool. 3. The normality checking step includes detecting a current flowing from the power supply, and determining a first current having a value greater than 0 and a second current having a value greater than the first current. The cutting tool position control method according to claim 2, wherein the normality is confirmed when the magnitude is smaller than the current. 4. The cutting tool position control method according to claim 1, wherein the object to be contacted is an object attached to the machine tool. 5. A contact probe according to claim 1, wherein a touch probe is provided so as not to move relative to the blade, and a contact detection step of detecting contact between the touch probe and the contacted object is performed. Tool position control method. 6. In a machine tool, a cutting tool and a contacted object are relatively moved by a moving device capable of detecting a moving position so that they are brought into contact with each other, and a subsequent cutting tool is determined based on a moving position of the moving device at the time of contact. A tool position control device that controls the relative movement between the tool and the workpiece, wherein a contact detection device that detects contact between the tool and the workpiece detects the contact between the tool and the workpiece. A confirmation unit that confirms that it is in a state in which the blade tool and the object can be brought close to the moving device after confirmation by the confirmation unit or in a state where the confirmation is continued. A tool position control device, comprising: a contact detection unit configured to detect contact with an object. 7. In a machine tool, a cutting tool and a contacted object are relatively moved by a moving device capable of detecting a moving position, and the two are brought into contact with each other, and the subsequent cutting tool is determined based on the moving position of the moving device at the time of contact. And a cutting tool position control device that controls the relative movement of the workpiece and the cutting tool, the contact tool and the power supply are connected in series, and a closed circuit is formed when the cutting tool and the contact tool are in contact with each other. A first circuit that is open when not in operation, and a closed circuit that is connected to the power supply in parallel with the first circuit and that includes at least an electrical resistance in series regardless of contact or non-contact between the blade and the contacted object. Forming a second circuit, a detector for detecting a state of the power supply, and a detection result of the detector in a state where the first circuit is in an open circuit, at least the detector and the power supply are normal. A place to show that there is On the basis of the moving position of the moving device at the time when the detection result of the detector becomes a result indicating the contact between the blade tool and the contacted object, the blade tool and the contacted object approach the moving device. And a control device for controlling the moving device thereafter. 8. An insulating device for electrically insulating the cutting tool or a cutting tool side portion that is in a state of being electrically connected to the cutting tool and a main body of a machine tool, wherein the electric resistance is equal to the cutting tool side portion. The cutting tool position control device according to claim 7, which is disposed between the cutting tool and a main body of the machine tool. 9. A workpiece holding member that holds a workpiece of a machine tool itself or a workpiece holding member side portion that is a portion that is in an electrically conductive state with the workpiece holding member; The cutting tool position control according to claim 7, further comprising an insulating device for electrically insulating the main body from the main body, wherein the electric resistance is disposed between the workpiece holding member side portion and the main body of the machine tool. apparatus. 10. The surface of at least one of the members located on both sides of the electric resistance in the second circuit,
The blade tool position control device according to any one of claims 7 to 9, wherein at least a portion adjacent to a surface of the other member is covered with a layer of an electrically insulating material. 11. The detection result of the detector in a state where the control device makes contact between the cutting tool and the contacted object by cutting fluid even though the cutting tool and the contacted object are separated from each other. The cutting tool position control device according to any one of claims 7 to 10, wherein the detection is performed according to a detection result that can be distinguished from the above. 12. When the controller does not detect contact between the cutting tool and the contacted object even though it is clear that the cutting tool and the contacted object are at a relative position to be contacted. The blade position control device according to any one of claims 7 to 11, further comprising a loss determination unit that determines that there is a possibility that the blade has lost.