JP2007276031A - Method and apparatus for monitoring processing target gripping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for monitoring a processing target gripping device capable of improving safety. <P>SOLUTION: The processing target gripping device 21 has: a gripping force detecting device 2; a notification device 3 for notifying the operator of gripping fault; a storage portion 6 for storing a threshold value of the gripping force; a computation potion 5; and a control potion 4 for operating the notification device 3 by comparing the detected value of the gripping force from the gripping force detecting device 2 to the threshold value stored in the storage portion 6 by the computation portion 5 when it is determined if the gripping force of the processing target W by a claw 27 of the processing target gripping device 21 is abnormal or not and it is determined that the gripping force is abnormal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a monitoring method for a processing object grasping means and a monitoring apparatus for the processing object grasping means suitable for rotating and processing the processing object grasped by the processing object grasping means safely.

  Conventionally, in machine tools, for example, lathes such as ordinary lathes, automatic lathes, NC lathes and CNC lathes, and cylindrical grinders, a workpiece (workpiece) can be freely attached to and detached from the tip of a spindle that is rotationally driven. A workpiece grasping means (chuck) having a plurality of claws for grasping is attached. Then, the workpiece is clamped from outside or inside by the workpiece grasping means, and then rotated together with the workpiece grasping means attached to the spindle, and the tool (tool or grindstone) is rotated. Processing (cutting or grinding) is performed in contact with the workpiece.

  As the processing object grasping means for grasping the processing object, the chuck body (chuck body) having rigidity attached to the tip of the spindle rotatably supported by the headstock is used to grasp the processing object in the radial direction. A plurality of freely openable / closable jaws (jaws) are provided.

  Further, as such a workpiece grasping means, there are a hand-tightening chuck for manually opening and closing a claw used for a normal lathe and an actuator for driving a claw opening and closing used for an NC lathe. There is a power chuck that uses a driving force.

  The hand-tightening chuck includes a single chuck in which each claw moves independently and an interlocked chuck in which each claw moves together.

  A power chuck is generally used as a means for grasping a workpiece in recent years because it can easily improve productivity and reduce costs by reducing machining time without manpower. (For example, refer to Patent Document 1).

  A conventional power chuck will be described by exemplifying a hydraulic chuck using a hydraulic cylinder as an actuator.

  In the conventional hydraulic chuck, a hydraulic cylinder provided at the rear of the main shaft is driven by hydraulic pressure, and a draw pipe (draw tube) as a connecting member disposed in the main shaft is moved forward and backward, thereby a wedge mechanism of the chuck body. A plurality of claws, which are detachably fixed with bolts or the like to a master jaw provided in the chuck body via a transmission mechanism such as a lever mechanism, are configured to be moved forward and backward in the radial direction so as to be opened and closed simultaneously.

  By the way, when a workpiece is grasped and processed by the nail of the workpiece grasping means, if the workpiece is rotated, the grasping force for the workpiece to be grasped by the nail is reduced by the centrifugal force accompanying the rotation or It is known to increase.

  For example, when grasping an object to be processed from the outside (grasping the outer diameter) with the nail of the hydraulic chuck, machining with the nail is performed as shown in the grasping force decrease diagram showing the relationship between the rotation speed and the grasping force in FIG. When the grasping force in the set state in which the object is grasped (non-rotating state in which the rotation speed is not applied to the object to be processed is 12KN) is 12 KN, the grasping force is the centrifugal force when the rotation speed becomes 5000 per minute. As a result, 4KN decreases to 8KN. FIG. 10 also shows the relationship between the rotational speed and the grasping force when the grasping force in the set state is 10 KN and 6 KN.

  Therefore, the grasping force in the set state when grasping the outer diameter of the workpiece with the claw of the hydraulic chuck does not cause shortage in consideration of the rotational speed, that is, the decrease due to the centrifugal force based on the experience of the operator. Is set to.

  In addition, when grasping a cylindrical workpiece or the like from the inside with the claws of the hydraulic chuck (inner diameter grasping), as shown in the grasping force increasing diagram showing the relationship between the rotational speed and the grasping force in FIG. Assuming that the grasping force in the set state is 4 KN, when the rotational speed is 5000 per minute, it is increased by 4 KN to 8 KN due to the influence of centrifugal force. FIG. 11 also shows the relationship between the rotational speed and the grasping force when the grasping force in the set state is 6KN, 8KN, and 10KN.

  Therefore, the grasping force in the set state when grasping the inner diameter of the workpiece with the claw of the power chuck is based on the operator's experience, etc., due to the rotation speed, that is, the increase due to centrifugal force and the increase in the grasping force of the workpiece. Considering not to deform, it is set so as not to be excessive.

  Note that the grasping force of the object to be processed by the claw of the hydraulic chuck is directly proportional to the force in the axial direction of the piston of the hydraulic cylinder (output of the hydraulic cylinder), and consequently the hydraulic pressure of the hydraulic cylinder. An example of the relationship between the gripping force and the piston force is shown in the diagram of FIG. An example of the relationship between the gripping force and the hydraulic pressure of the hydraulic cylinder is shown in the diagram of FIG.

  By the way, since the grasping force of the object to be processed by the nail of the object to be processed grasping means increases / decreases due to the centrifugal force, it is necessary to set the grasping force after performing the processing after recognizing the relationship between the rotational speed and the grasping force. It will be greatly affected in terms of accuracy and safety.

  In particular, in recent years when high-speed machining is required for reasons such as improving productivity and reducing costs by shortening machining time, it is necessary to set the grasping force after recognizing the relationship between the rotation speed and grasping force. It is more important in terms of machining accuracy and safety.

  Therefore, a grasping force measuring device has been proposed that can directly measure the grasping force and the rotational speed by causing the workpiece grasping means to grasp the rotating body for measurement (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 6-42005 (FIG. 2) Japanese Patent Laid-Open No. 07-308808

  However, the conventional grasping force measuring device has a problem that it cannot respond to the recent improvement in safety.

  That is, in the conventional grasping force measuring device, by simply grasping the rotating body instead of the object to be processed by the object grasping means, simply measure in advance the relationship between the grasping force due to the centrifugal force and the rotational speed, The detected value of the grasping force and the value of the rotational speed obtained are merely displayed on an external display device, and the set state and the processing object are set with the processing object set on the nail of the processing object grasping means in an actual machine tool. There is a problem in that it is impossible to monitor grasping force in a rotating state (including during processing) in which an object is rotated.

  This is because the grasping force of the object to be processed by the object grasping means is not only the increase / decrease due to the influence of the centrifugal force, but also various centrifugal forces such as external force represented by cutting force or grinding force applied to the object under rotation. Factors other than force can cause imbalance or decrease.

  For example, if the workpiece has burrs such as forging or casting, if the burrs are large, the machining allowance will be different between the burrs and other parts. Becomes imbalanced or decreases.

  Thus, if the grasping force becomes unbalanced or decreases during machining due to factors other than centrifugal force and the grasping force of the object to be processed is insufficient, the object to be grasped by the nail during machining will be eccentric. There is a risk that the object to be processed slips on the gripping surface of the nail or the object to be processed is detached from the nail and flies around.

  In the case of a power chuck, breakage of the draw pipe, leakage of the working fluid of the actuator (leakage from the hydraulic oil piping in the hydraulic chuck, leakage from the compressed air piping in the pneumatic chuck), fluctuations in the temperature of the working fluid (Changes in temperature of hydraulic oil in hydraulic chucks, temperature changes in compressed air in pneumatic chucks), deterioration of working fluid (deterioration of hydraulic oil in hydraulic chucks), deterioration of actuators (deterioration of coils in electric chucks), etc. There is a decrease.

  In addition, grease placed on sliding parts such as the master jaw in the power chuck may be washed away by cutting fluid or grinding fluid, or chips may enter the sliding parts and mix with the grease. There is a decrease in gripping force when the sliding resistance of the moving part increases.

  If the gripping force decreases due to factors other than centrifugal force and the gripping force of the workpiece is insufficient, the original gripping force can be obtained even if a predetermined force is applied from the drive source in the set state. In other words, the grasping force of the workpiece in the rotating state cannot be obtained as the original grasping force.

  Therefore, there is a need for a monitoring method for a processing object grasping means and a monitoring apparatus for the processing object grasping means that can improve safety.

  This invention is made in view of such a point, and it aims at providing the monitoring method of the workpiece grasping means and the monitoring apparatus of the workpiece grasping means which can aim at the improvement of safety. .

  In order to achieve the above-described object, the feature of the method for monitoring a workpiece grasping means according to the present invention is that a chuck body attached to the tip of a spindle that is rotatably supported by the spindle stock, and that the chuck body can be freely opened and closed. A grasping force detection means for detecting a grasping force of the object to be processed by the plurality of claws of the object grasping means provided with a plurality of claws provided, and a detected value of the grasping force detected by the grasping force detection means Is compared with a preset threshold value to determine whether there is an abnormality in the grasping force of the object to be processed by the object to be grasped, and if it is determined that there is an abnormality in the grasping force, The point is to notify.

  When the threshold value is a lower limit value and the detection value is less than the threshold value, it is preferable to determine that the grasping power is insufficient, the threshold value is an upper limit value, and the detection value is less than the threshold value. When it exceeds, it is preferable to determine that the grasping force is excessively abnormal. Furthermore, the threshold value is an allowable range constituted by two of a lower limit value and an upper limit value, and the detected value is outside the allowable range. In this case, it is preferable to determine that the grasping power is insufficient or excessive.

  Further, the monitoring device of the workpiece grasping means according to the present invention is characterized in that a chuck body attached to the tip end of a spindle rotatably supported on the spindle head and a plurality of claws provided on the chuck body so as to be opened and closed. A grasping force detecting means for detecting grasping force of the object to be processed by a plurality of freely openable / closable claws, and a notice for notifying an operator of abnormality in grasping force of the object to be processed by the plurality of nails And a storage unit for storing a threshold value of grasping force of the processing object by the plurality of nails, and a calculation unit, and the detection value of the grasping force sent from the grasping force detection unit by the calculation unit is stored in the storage unit. Control for operating the notification means when it is judged that there is an abnormality in the grasping force of the object to be processed by the object grasping means by comparing with the threshold value stored in the section. Department and There in that it has.

  The threshold value is a lower limit value, and the control unit is preferably configured to determine that the grasping power is insufficient when the detected value is less than the threshold value, and the threshold value is an upper limit value. Preferably, the control unit determines that the grasping force is excessively abnormal when the detected value exceeds the threshold value. Further, the threshold value is constituted by two of a lower limit value and an upper limit value. Preferably, the control unit determines that the grasping power is insufficient or excessively abnormal when the detected value is outside the allowable range.

  The grasping force detecting means is preferably provided on the nail. The plurality of claws are preferably formed to be openable and closable by a driving force of an actuator as a driving source connected through a connecting member, and the actuator is preferably a hydraulic cylinder. Further, the grasping force detecting means is preferably disposed on at least one of the plurality of claws, the connecting member, and the actuator, and the grasping force detecting means is preferably a strain gauge. Furthermore, it is preferable that the chuck body is attached to the tip of the main shaft via an attachment member, and the notification means is provided on the attachment member.

  According to the monitoring method of the processing object grasping means according to the present invention, the grasping force of the processing object by the nail of the processing object grasping means is detected to determine whether or not the grasping force is abnormal, and the grasping force is abnormal. If it is determined, the operator can be notified of the abnormality, so that the operator can easily recognize the abnormality in the grasping power of the workpiece by the workpiece grasping means.

  Moreover, according to the monitoring apparatus for the processing object grasping means according to the present invention, the monitoring method for the processing object grasping means of the present invention can be easily implemented.

  Therefore, according to the monitoring method of the processing object grasping means and the monitoring apparatus of the processing object grasping means according to the present invention, safety can be improved.

  The present invention will be described below with reference to embodiments shown in the drawings.

  FIG. 1 is a block diagram showing a main part of an embodiment of a monitoring device for a workpiece grasping means according to the present invention.

  As shown in FIG. 1, a monitoring device (hereinafter simply referred to as a monitoring device) 1 for a processing object grasping means 1 of this embodiment has a grasping force detection means 2, a notification means 3, and a control unit 4. Yes. In addition, the structure of the workpiece target grasping means 21 using the monitoring device 1 of the present embodiment will be described later.

  The grasping force detection means 2 is for detecting the grasping force of the workpiece W by the claw 27 of the workpiece grasping means 21 described later, and is electrically connected to the control unit 4 by wire or wirelessly. Yes. And the grasping force when the processing object grasping means 21, specifically, the claw 27 of the processing object grasping means 21 grasps the processing object W, is detected, and the detected value of the grasping force is sent to the control unit 4. It can be sent out.

  As the grasping force detection means 2, a force sensor is used. The force sensor can be selected from various types such as a strain gauge, a pressure sensor using a strain gauge, and a pressure sensor using a semiconductor.

  In this embodiment, as will be described later, a strain gauge 2a (FIG. 2) using a metal wire for measuring strain in one direction is mainly used. As such a strain gauge 2a, one that measures strain in one direction is used, one that measures strain in one direction is used in combination in two directions orthogonal to each other, or two directions that are orthogonal to each other. Can be selected from various gauge patterns such as those for measuring

  The strain gauge 2a is electrically connected to the control unit 4 through a bridge circuit and an amplifier in this order. A bridge circuit and an amplifier may be incorporated in the control unit 4.

  The notification means 3 is for notifying the operator of an abnormality in grasping power, is electrically connected to the control unit 4 by wire or wirelessly, and is recognized by the operator by a control command sent from the control unit 4 Operation control for making it happen is made.

  As the notification means 3, a display panel such as a liquid crystal display panel, a sound generator such as a buzzer or a speaker, a safety light formed by various light sources such as a light emitting diode (LED) 3a (FIG. 2), etc. are used alone. Alternatively, two or more kinds can be used in combination.

  When a sound generator is used as the notification means 3, the volume, tone color, and interval may be used alone or in combination.

  Moreover, when using a safety light as the notification means 3, it is good to carry out movements, such as a color, a color tone, blinking, and rotation, individually or in combination.

  The control unit 4 determines whether there is an abnormality in the grasping power of the processing object by the processing object grasping means 21, and when it is determined that there is an abnormality in the grasping force, the control means 4 operates the notification means 3 to It is for notifying abnormality, and has a calculation unit 5 formed by a CPU or MPU and a storage unit 6 formed by a ROM and / or RAM having an appropriate capacity. The control unit 4 is electrically connected to an operation panel 7, a power supply 8, and the like by wire or wirelessly.

  The operation panel 7 has an input of a threshold value used to determine whether or not the grasping force is abnormal, or the rotational speed of the spindle 24 (FIG. 2) necessary for calculating the threshold value, the machining allowance, or the type of material. For inputting various information such as machining conditions such as tool type, machining allowance obtained from literature or experiments, tool type, machining resistance (cutting resistance, grinding resistance) related to the composition of the workpiece W Various switches 10 such as an input unit 9 to be used and a power switch for turning on / off the power source 8 are connected.

  The operation panel 7 displays the detected value of the grasping force detected by the grasping force detecting means 2, the input information, the setting information such as the set threshold value, and the abnormality of the grasping force in characters, figures, symbols, etc. A display screen that can be used is preferably provided. As the input means 9 in this case, a planar input device such as a touch panel in which a plurality of menu screens can be arranged on a display screen may be used. When a plurality of different threshold values are stored in the storage unit 6 in advance, a selection switch for selecting one corresponding to the processing condition from the plurality of threshold values may be provided on the operation panel 7. The operation panel 7 may be integrated with the control unit 4 or may be provided separately from the control unit 4.

  The storage unit 6 compares various data such as a threshold value used to determine whether or not there is an abnormality in grasping force and the detected value of the grasping force sent from the grasping force detection unit 2 with the threshold value to determine whether the grasping force abnormality is present. Various programs such as a program for determining presence or absence and a program for operating the notification means 3 when it is determined that there is an abnormality in the grasping power are stored.

  The determination of whether there is an abnormality in grasping power is, for example, a threshold value is set as a lower limit value, and when the detected value is less than the threshold value, it is determined that the grasping power is insufficient, or the threshold value is set as an upper limit value. When the value exceeds the threshold value, it is possible to exemplify what determines that the grasping power is excessively abnormal. That is, when determining that the grasping power is insufficient as an abnormality, the lower limit value of the grasping force is used as a threshold value. When determining that the grasping force is excessive as an abnormality, the upper limit value of the grasping force is preferably used as a threshold value.

  Of course, the threshold value may be an allowable range constituted by the lower limit value and the upper limit value, and when the detected value is outside the allowable range, it may be determined that the grasping power is insufficient or excessively abnormal. That is, when it is determined that both the shortage and excess of the grasping force are abnormal, it is preferable to use an allowable range of the grasping force constituted by two threshold values of the upper limit value and the lower limit value of the grasping force.

  As the threshold value, a value based on the experience of the operator or the like is frequently used at the installation site of the machine tool.

  Of course, values calculated from various theoretical formulas may be used.

As the theoretical formula, when the workpiece W is cylindrical and the outer diameter is grasped,
Fg−Fc ≧ s (Pv · dc / μ · dg)
Can be mentioned.

  Here, Fg is a grasping force (N) at the time of setting, Fc is a grasping force (N) that decreases due to centrifugal force, s is a safety factor (2 to 4.5), and Pv is a main cutting (grinding) resistance (N). , Dc is the diameter (mm) of the processed part, μ is the coefficient of static friction of the grasping part, and dg is the diameter (mm) of the grasping part. Note that the value of μ is the state of the surface such as whether the gripping surface of the nail is a smooth surface or a grid-like groove surface, whether the surface of the workpiece to be grasped by the nail is a finished surface, or a rough finish surface However, in the case of steel, a value of 0.03 to 0.7 is used.

  The program not only determines whether there is an abnormality in grasping power but also determines that there is no abnormality in grasping power (appropriate range or appropriate value). It is also possible to determine the state of grasping power such as being away from (having a margin) in multiple stages. In this case, it is preferable that the range of the grasping power at each stage is stored in the storage unit 6 as a plurality of different threshold values, and it is determined which range the grasping force detected by the grasping force detecting means 2 is applied. . Further, when performing multi-stage discrimination, it is preferable that the notification means 3 performs multi-stage notification.

  For example, if a sound generator is used, the volume, tone, interval, etc. may be controlled in multiple steps, alone or in combination, and if a safety light is used, the type of color, blinking interval, rotation speed, etc. Multi-stage control may be performed alone or in combination. In addition, as in a traffic signal, a configuration in which abnormality in grasping power is displayed in red, yellow is displayed when the detected value of grasping power is close to the threshold, and blue is displayed when the detected value of grasping power is away from the threshold. it can.

  The storage unit 6 may store a program for calculating a threshold value based on various input information such as machining conditions and various data input from the input unit 9 and storing the threshold value in the storage unit 6.

  Further, the storage unit 6 stores a program for operating the notification unit 3 by determining that the processing abnormality such as chatter is detected when the detected value of the grasping force detected by the grasping force detection unit 2 fluctuates in a short time. Also good. In this case, it is preferable to set a fluctuation range and / or a threshold value of the fluctuation period for discriminating machining abnormality.

  Furthermore, when a power chuck is used as the workpiece grasping means 21, the notification means 3 is operated when the memory 6 determines that the grasping force is abnormal, and the grasping force by the power chuck is increased. As described above, a program for sending a control command for controlling the operation of the power chuck, or a program for sending a control command for stopping the spindle while operating the notification means 3 when it is determined that the grasping force is abnormal is stored. Good.

  Further, the operation panel 7 may not be provided. In this case, it is preferable to store a plurality of threshold values in the storage unit 6 in advance and select a threshold value to be used by operating a selection switch such as a dip switch. In this case, it is necessary to connect a power switch to the control unit 4.

  Further, the functions of the notification means 3, the control unit 4 and the operation panel 7 can be implemented by a personal computer and its display. The control panel is used when the machine tool is NC, and the control is executed when the machine tool is CNC. It can be set as the structure incorporated and implemented in a board. In this case, it is important that the grasping force detected by the grasping force detecting means 2 is remotely measured.

  Here, an embodiment of the processing object grasping means using the monitoring device of the present embodiment will be described.

  FIG. 2 is a cross-sectional view showing a main part of an embodiment of the processing object grasping means using the monitoring device for the processing object grasping means according to the present invention.

  The workpiece grasping means for which the monitoring device of this embodiment is used exemplifies a hydraulic chuck as a power chuck.

  As shown in FIG. 2, the workpiece grasping means 21 of this embodiment has a chuck body 22 that is formed in a substantially cylindrical shape as a whole by a material having rigidity such as steel. The chuck body 22 is attached to the front end of a spindle 24 of a machine tool such as an NC (numerical control) lathe by a fixing bolt or the like through a back plate 23 as an attachment member at the rear end shown on the left side of FIG. The main shaft 24 and the chuck body 22 are integrally rotated. The spindle 24 is rotatably supported on the spindle stock 25. Further, the back plate 23 is provided for versatility of attaching the chuck body 22 to various (including different sizes) machine tools, and the chuck is attached to the tip of the spindle 24 without using the back plate 23. The structure which attaches the main body 22 directly may be sufficient.

  The chuck body 22 is provided with a master jaw 26 that is movable in the radial direction by a guide groove formed in the chuck body 22. A plurality of (for example, three) master jaws 26 are provided at predetermined angles (for example, 120 degrees). The claw side end of the master jaw 26 is provided with a T groove and one serration, and the other serration is formed on the master jaw side end surface of the claw 27. The claws 27 whose positions are determined by the engagement of the serrations are respectively fixed to the master jaws 26 by screwing bolts 28 into the screw holes of the T nuts fitted in the T grooves. With these claws 27, the workpiece W is grasped from a plurality of directions (for example, three directions), the spindle 24 is rotationally driven, and the workpiece W and a tool such as a tool are moved in the axial direction of the spindle 24 and the spindle. The workpiece W is processed by being relatively moved in a direction orthogonal to the 24 axial directions.

  The claw 27 is opened and closed by driving a wedge member 29 disposed on the chuck body 22 in the front-rear direction (main shaft 24 axis direction), thereby moving the master jaw 26 engaged with the wedge member 29 in the radial direction. Has been done. The wedge member 29 is engaged with the front / rear drive member 30 and is driven in the axial direction by the drive of the front / rear drive member 30. The front / rear drive member 30 is coupled to a draw pipe 31 as a connecting member by screw coupling.

  The draw pipe 31 is formed so as to be movable only in the axial direction of the main shaft 24 with respect to the main shaft 24, and by moving the draw pipe 31 forward and backward in the front-rear direction (right and left in FIG. 2). The front / rear drive member 30 is driven in the front / rear direction, and as a result, the pawls 27 can be reciprocated in the radial direction to be opened / closed.

  On the rear end side of the main shaft 24, a return type hydraulic cylinder 32 as an actuator as a drive source is disposed with the tip of a piston 33 as an output shaft facing the chuck body side. Is connected to the rear end of the draw pipe 31. The piston 33 is provided so as to be movable in the axial direction with respect to the main shaft 24 by driving the hydraulic cylinder 32. The piston 33 is disposed inside the cylinder 34 of the hydraulic cylinder 32 so as to be capable of reciprocating in the axial direction.

  Therefore, the workpiece grasping means 21 of the present embodiment includes a power chuck formed so as to be openable and closable by a driving force of an actuator that is a driving source connected to a plurality of claws 27 via a connecting member. 27 is a hydraulic chuck 21 a that is openable and closable by a driving force of a hydraulic cylinder 32 connected via a draw pipe 31.

  Since other configurations are the same as those of a conventionally known hydraulic chuck, detailed description thereof will be omitted.

  The above-described monitoring device 1 is disposed in the hydraulic chuck 21a as the workpiece grasping means 21 of the present embodiment.

  That is, as shown in FIG. 2, a strain gauge 2 a as the grasping force detecting means 2 is disposed on the side surface of the claw 27. In addition, a plurality of colors of light emitting diodes 3a as notification means 3 are arranged along the circumferential direction on the outer peripheral surface of the back plate 23. Inside the back plate 23, the control unit 4 is illustrated. 2 is arranged together with a power source 8 and an operation panel 7 not shown.

  The light emitting diode 3 a may be disposed on the outer peripheral surface of the chuck body 22. In this case, a concave portion is formed on the outer peripheral surface of the chuck body 22 so that the light emitting diode 3a does not protrude from the outer peripheral surface of the chuck body 22, and the light emitting diode 3a is accommodated in the concave portion, and the opening of the concave portion is made of a transparent material. This means that it is easy to prevent the light emitting diode 3a from being damaged due to contact with something, and it is possible to prevent the light emitting diode 3a from being applied with coolant, chips, or the like. Is preferable.

  In the workpiece grasping means 21 of the present embodiment, a strain gauge 2a as the grasping force detecting means 2 is also provided on the outer peripheral surface of the draw pipe 31, and the hydraulic cylinder 32 is also provided as the grasping force detecting means 2. A force (pressure) sensor 2b is provided.

  The gripping force detecting means 2 may be disposed at any location where the claw 27 is distorted by the gripping force when the workpiece W is gripped. In the case of the hydraulic chuck 21a, the claw 27 is disposed. The chuck body 22, the draw pipe 31, the hydraulic cylinder 32, etc. may be provided. Of course, the closer the grasping force detecting means 2 is to the grasping portion of the workpiece W, the better.

  In the case of a power chuck such as the hydraulic chuck 21a, a portion where distortion occurs due to a grasping force in the chuck body 22 can be a master jaw 26 or the like.

  That is, when the workpiece grasping means 21 is a power chuck, the grasping force detection means 2 is disposed on at least one of the plurality of claws 27, the connecting member (draw pipe 31), and the actuator as the driving source. It only has to be.

  Further, when the workpiece grasping means 21 is a hand-tightened chuck, the grasping force detecting means 2 is provided on the claw 27.

  The position at which the strain gauge 2a is disposed on the claw 27 can be set as required according to the specifications and design concept of the claw 27.

  For example, as shown in FIG. 3 to FIG. 5, when grasping the outer diameter of the workpiece W with the claw 27, the claw showing the longitudinal direction of the strain gauge 2 a for measuring strain in one direction in the vertical direction of FIG. 3. The structure arrange | positioned in parallel with the longitudinal direction of 27 at the both sides | surfaces of the nail | claw 27 can be mentioned. In this case, basically, the strain gauge 2a may be disposed on at least one of the plurality of claws 27. However, when the workpiece W is grasped by the plurality of claws 27, the workpiece W is eccentrically grasped. That only a part of the plurality of claws 27 (for example, two claws 27 out of the three claws 27) has been used for grasping the workpiece W, or a workpiece to be machined during machining. In the sense that it is possible to detect the eccentricity of the object W, it is preferable to dispose strain gauges 2a on all the claws 27.

  Further, in the sense that an imbalance in grasping force due to eccentricity of the workpiece W can be detected, a plurality of strain gauges 2a are separated from one claw 27, for example, left and right side surfaces ( 4 and 5), or on the left and right side surfaces of one claw 27 and preferably at different positions (FIGS. 8 and 9) from the main shaft 24.

  FIG. 6 shows an example of an arrangement position of the strain gauge 2a in the case where the inner diameter of the workpiece W is grasped by the claw 27.

  Further, as shown in FIGS. 7 and 8, a parent-child claw 37 comprising a parent claw 38 for fixing the claw 27 to the master jaw 26 and a child claw 39 that is detachably replaceable with respect to the parent claw 38. In this case, for example, two holes 40a and 40b having a rectangular section that is long in the vertical direction in FIG. 7 are formed in two places on the side surface of the parent claw 38 on the radially outer side and the radially inner side. As shown in FIG. 8, the configuration in which the strain gauges 2 a are respectively disposed on the left end side of the upper hole 40 a and the right end side of the lower hole 40 b of the two holes 40 a and 40 b is exemplified. it can. The holes 40a and 40b may be bottomed holes. Further, FIG. 9 shows a case where a wide claw 39a is used.

  Of course, the strain gauge 2a may be provided by forming a groove in the claw 27, or may be provided on the upper surface or the front surface of the claw 27.

  When the strain gauge 2 a is disposed on the draw pipe 31, the longitudinal direction of the strain gauge 2 a for measuring strain in one direction is basically disposed along the axial direction of the draw pipe 31. The strain gauge 2a that measures strain in one direction along the circumferential direction of the draw pipe 31 as shown in FIG. 2 is also used in the sense that the detection error due to the bending of the draw pipe 31 can be canceled. It is preferable to arrange. Of course, by using a strain gauge that can measure strain in two directions orthogonal to each other, the number of strain gauges to be used can be reduced to one and the installation space can be reduced. The strain gauge 2a may be disposed at one location in the substantially central portion of the draw pipe 31 in the axial direction. However, the strain gauge 2a can be arranged at both sides in the axial direction so that minute strains can be made with higher accuracy. It is preferable in the sense that it can be detected. In addition, the strain gauge 2a disposed on the draw pipe 31 and the control unit 4 may be electrically connected using, for example, a flexible wiring board.

  As shown in FIG. 2, when the grasping force detecting means 2 is disposed in the hydraulic cylinder 32, as shown in FIG. 2, a force sensor 2b for detecting the respective oil pressures in both moving directions of the piston 33 inside the cylinder 34. The structure which arrange | positions this to the cylinder 34, the structure (not shown) which arrange | positions the strain gauge 2a to the piston 33, etc. can be mentioned. Further, the pressure sensor 2b disposed in the hydraulic cylinder 32 and the control unit 4 may be electrically connected using, for example, a flexible wiring board and a slip ring.

  Next, the operation of the present embodiment having the above-described configuration will be described together with the monitoring method of the processing object grasping means of the present invention.

  The monitoring method of the processing object grasping means of the present embodiment (hereinafter simply referred to as the monitoring method) is the processing of the present embodiment shown in FIG. 2 provided with the monitoring device 1 of the present embodiment shown in FIG. This is performed using a hydraulic chuck 21a as the object grasping means 21.

  In the present embodiment, prior to processing the workpiece W, the operator performs a threshold setting operation used to determine whether there is an abnormality in grasping power. As described above, this setting operation is based on the grasping method of the workpiece W such as grasping the outer diameter or inner diameter, the composition, size, weight, machining conditions, etc. of the workpiece W, the experience of the operator, etc. When simply determining whether there is an abnormality in grasping power, a threshold value for use is input and stored in the storage unit 6, or a threshold value for use is selected from a plurality of threshold values stored in the storage unit 6 in advance. Or by performing an input operation of input information such as processing conditions and various data, and calculating a threshold value to be used by the calculation unit 5 of the control unit 4 and storing it in the storage unit 6.

  In the case where the grasping power is determined in multiple stages, a plurality of different threshold values are set.

  Next, the workpiece 27 is grasped by the claw 27 of the hydraulic chuck 21a and set to a set state. Then, the grasping force of the workpiece W grasped by the nail 27 by the grasping force detection means 2 is detected. The detected value of the grasping force indicates that the workpiece W is rotated until the workpiece W is removed from the claw 27, that is, in a non-rotating state where the spindle 24 is stopped, and the spindle 24 is rotated. It is detected over all the states such as the rotating state and the state in which the workpiece W is rotated and the workpiece is being processed, and is sent to the control unit 4 in real time.

  Next, the control unit 4 that has received the detected value of the grasping force detected by the grasping force detection means 2 stores the detected value of the grasping force in the set state and the storage unit 6 based on the program stored in the storage unit 6. The stored threshold value is compared to determine whether there is an abnormality in the grasping force of the workpiece W by the nail 27 in the set state.

  For example, when determining that there is an abnormality in grasping power, it is determined that there is no abnormality in grasping force when the detected value of grasping force is equal to or greater than a threshold value including a lower limit value. If the detected value of the grasping force is less than the threshold value, it is determined that the grasping force is abnormal (insufficient grasping force). As described above, the grasping power may be determined in multiple stages.

  Further, in order to determine whether or not there is an abnormality in other grasping force, the workpiece W has a thin shape, and it is determined that an excess of grasping force that causes the workpiece W to deform when it is grasped with a strong force is abnormal. In this case, it is determined that there is no abnormality in the grasping force when the detected value of the grasping force is equal to or lower than the threshold value including the upper limit value, and there is an abnormality in the grasping force when the detected value of the grasping force exceeds the threshold value (the grasping force It is good to judge that it is excessive.

  Furthermore, when both the shortage and excess of the grasping force are concerned, an allowable range of grasping force constituted by two threshold values, a lower limit value and an upper limit value, is set, and the detected value is outside the allowable range In addition, it may be determined that there is an abnormality in grasping ability (insufficient grasping ability or excess grasping ability).

  At this time, if the control unit 4 determines that the grasping force is abnormal, the control unit 4 drives the notification means 3. As a result, it is possible to notify the operator to recognize an abnormality in the grasping force in the set state. When the grasping power is discriminated in multiple stages, the notification means 3 is driven in multiple stages. Further, not only the presence / absence of the grasping force but also the detected value of the grasping force detected by the plurality of grasping force detecting means 2 regardless of the presence / absence of the grasping force, for example, the strain gauge 2a disposed on each nail 27 By comparing the detection values of the grasping force detected by the above, an abnormality in the grasping state such as the eccentricity of the workpiece W can be detected.

  Next, in the rotation state in which the workpiece W is rotating, the control unit 4 also detects the grasping force in the rotation state and the threshold value stored in the storage unit 6 (the set state is the same as in the set state). If the control unit 4 determines that the grasping force is abnormal, the control unit 4 causes the notification means 3 to be notified. To drive. Thereby, it is possible to notify the operator to recognize the abnormality of the grasping force in the rotation state. When the grasping power is discriminated in multiple stages, the notification means 3 is driven in multiple stages.

  Further, as another determination of the presence / absence of another grasping force abnormality, the storage unit 6 stores the fluctuation period and / or the fluctuation width threshold value of the grasping force detection value detected by the grasping force detection means 2. In addition, when the fluctuation cycle becomes shorter than the threshold value or the fluctuation range becomes larger than the threshold value, when the program for operating the notification means 3 is determined by determining the machining abnormality such as chattering, the machining accuracy or It is possible to interrupt the processing of the processing object in which a problem has occurred.

  As described above, according to the monitoring method of this embodiment, the plurality of claws 27 that are openable and closable on the hydraulic chuck 21a serving as the workpiece grasping means 21 attached to the tip of the spindle 24 rotatably supported on the spindle stock 25 are provided. The grasping force detection means 2 for detecting the grasping force of the object W to be machined is provided, and the object to be machined by the hydraulic chuck 21a is compared by comparing the detected value of the grasping force detected by the grasping force detection means 2 with a preset threshold value. When it is determined whether there is an abnormality in the grasping force of the object W and it is determined that there is an abnormality in the grasping force, it is possible to notify the operator of the abnormality, so that the processing target grasped by the claw 27 of the hydraulic chuck 21a Abnormal grasping force in the set state of the object A and whether there is an abnormality in grasping force including the case of being affected by the centrifugal force in the rotating state is reliably and easily monitored in real time. It is Rukoto, if there is an abnormality can be recognized easily and reliably to the operator. As a result, it is possible to prevent the processing object W from being processed abnormally including a decrease in processing accuracy, to prevent the processing object W from coming off the claw 27 during processing, and to recognize the risk of occurrence of these problems to the operator. Can be made.

  Further, according to the monitoring method of the present embodiment, when the threshold value is set to the lower limit value and the detected value is less than the threshold value, it is possible to determine that the grasping power is insufficient, so it is possible to determine in real time whether the grasping power is insufficient. Therefore, the operator can be surely and easily monitored, and when there is an abnormality, the operator can easily and surely recognize it.

  Furthermore, according to the monitoring method of the present embodiment, when the threshold value is set as the upper limit value and the detected value exceeds the threshold value, it is possible to determine that the grasping ability is excessively abnormal. Therefore, the operator can be surely and easily monitored, and when there is an abnormality, the operator can easily and surely recognize it.

  Furthermore, according to the monitoring method of the present embodiment, the threshold is set to an allowable range composed of the lower limit value and the upper limit value, and when the detected value is outside the allowable range, the grasping power is insufficient or excessively abnormal. Because it can be judged, it is possible to monitor in real time whether there is a lack of grasping ability or an abnormality in grasping ability in a reliable and easy manner, and if there is an abnormality, the operator can easily and reliably recognize it. Can do.

  Further, according to the monitoring method of the present embodiment, the operator can recognize whether or not the nail 27 properly grasps the workpiece W visually and / or auditoryly by the notification means 3. No stress is generated against danger such as the workpiece W coming off the nail 27 during processing, and a comfortable operation can be performed.

  In addition, according to the monitoring device 1 of the present embodiment, the grasping force detection means 2, the notification means 3, the storage unit 6 and the calculation unit 5 in which a grasping force threshold value is stored are included. The detected value of the grasping force sent from the detection means 2 is compared with the threshold value stored in the storage unit 6 to determine whether or not the grasping force of the workpiece W by the hydraulic chuck 21a as the workpiece grasping means is abnormal. When it is determined that the grasping force is abnormal, the control unit 3 that operates the notification unit 3 is provided. Therefore, the monitoring method of the present invention, that is, the detection of the grasping force detected by the grasping force detection unit 2 is provided. When it is determined that there is an abnormality in the grasping force of the workpiece W by the hydraulic chuck 21a as the workpiece grasping means 21 by comparing the value with a preset threshold value, Operate that it is abnormal The monitoring method for notifying can be carried out easily.

  Furthermore, according to the monitoring device 1 of the present embodiment, the threshold value is set to the lower limit value, and the control unit 3 is configured to determine that the grasping power is insufficient when the detected value is less than the threshold value. Monitoring according to the present embodiment in which a threshold is set as a lower limit, and when the detected value is less than the threshold, it is determined that the grasping power is insufficient, and when it is determined that the grasping power is abnormal, the operator is notified of the abnormality. The method can be carried out easily and reliably.

  Furthermore, according to the monitoring device 1 of the present embodiment, the threshold value is set as the upper limit value, and the control unit 3 is configured to determine that the grasping power is excessively abnormal when the detected value exceeds the threshold value. In this embodiment, the threshold value is set as the upper limit value, and when the detected value exceeds the threshold value, it is determined that the grasping power is excessively abnormal, and when it is determined that the grasping force is abnormal, the operator is notified of the abnormality. The monitoring method can be implemented easily and reliably.

  Furthermore, according to the monitoring device 1 of the present embodiment, the threshold value is set to an allowable range composed of the lower limit value and the upper limit value, and the control unit 3 has a grasping power when the detected value is outside the allowable range. Since it is configured to determine that the abnormality is insufficient or excessive, the threshold is set to an allowable range consisting of two lower and upper limits, and if the detected value is outside the allowable range, the grasping ability is insufficient or excessive If it is determined that there is an abnormality in the grasping power, the monitoring method of this embodiment for notifying the operator of the abnormality can be implemented easily and reliably.

  Furthermore, according to the monitoring device 1 of the present embodiment, since the strain gauge 2a as the grasping force detection means 2 is provided on the claw 27, the grasping force can be detected reliably and easily. By providing such a grasping force detecting means 2 on the claw 27, it is possible to reliably detect an abnormality in grasping force when a hand-tightened chuck is used as the workpiece grasping means 21.

  Furthermore, according to the monitoring apparatus 1 of the present embodiment, the workpiece grasping means 21 is formed so as to be freely opened and closed by the driving force of an actuator having a plurality of claws 27 connected via a draw pipe 31 as a connecting member. Therefore, it is possible to reliably detect the presence or absence of an abnormality in the grasping force of the workpiece W in a power chuck that has been frequently used in recent years.

  Further, according to the monitoring apparatus 1 of the present embodiment, since the actuator is the hydraulic cylinder 32, whether or not there is an abnormality in the grasping force of the workpiece W in the hydraulic chuck 21 as a power chuck that has been most frequently used in recent years is ensured. Can be detected.

  Further, according to the monitoring device 1 of the present embodiment, the grasping force detection means 2 is disposed on at least one of the plurality of claws 27, the draw pipe 31 as the connecting member, and the hydraulic cylinder 32 as the actuator. Therefore, it is possible to reliably detect the presence or absence of abnormality in the grasping force of the workpiece W. In this case, by disposing the strain gauge 2a on the draw pipe 31, in addition to the presence or absence of abnormality in the grasping force of the workpiece W by the claw 27, the presence or absence of abnormality in the grasping force caused by breakage of the draw pipe 31 is determined. Further, it is possible to determine an input abnormality, that is, an abnormality that the hydraulic pressure of the hydraulic cylinder 32 is too high or too low. Further, by disposing the pressure sensor 2b in the hydraulic cylinder 32, in addition to the presence or absence of abnormality in the grasping force of the workpiece W by the claw 27, it occurs due to leakage of the hydraulic oil from the piping, temperature change of the hydraulic oil, and the like. Whether or not the grasping force is abnormal can be determined.

  Moreover, according to the monitoring apparatus 1 of this embodiment, since the grasping force detection means 2 is the strain gauge 2a, the grasping force detection means 2 can be formed with a low cost and excellent availability.

  Further, according to the monitoring device 1 of the present embodiment, the chuck body 22 is attached to the tip of the main shaft 24 via the back plate 23 as an attachment member, and the notification means 3 is provided on the attachment member 24. Therefore, it is possible to provide versatility for attaching the chuck body 22 to the main spindle 24 of various machine tools including different sizes, and it is not necessary to provide the notification means 3 in a wide variety of chuck bodies 22. As a result, the overall cost can be reduced.

  Therefore, according to the monitoring method and the monitoring device 1 of the present embodiment, it is possible to easily and reliably improve safety.

  The monitoring method of the processing object grasping means and the monitoring device of the processing object grasping means of the present invention can also be used as a tool grasping means for grasping a tool.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

The block diagram which shows the principal part of embodiment of the monitoring apparatus of the workpiece grasping means which concerns on this invention. Sectional drawing which shows the principal part of embodiment of the workpiece target grasping means using the monitoring apparatus of the workpiece target grasping means which concerns on this invention. FIG. 2 is a half cross-sectional view showing the main part of an example of the position of the strain gauge when the outer diameter of the workpiece of FIG. 2 is grasped. Side view of essential parts of FIG. Plan view of the main part of FIG. The same figure as FIG. 3 which shows the principal part of an example of the arrangement | positioning position of the strain gauge in the case of grasping | ascertaining the internal diameter of the workpiece of FIG. The same figure as FIG. 3 which shows the principal part of an example of the arrangement | positioning position of the strain gauge in the case of grasping | ascertaining an outer diameter with a parent-child nail | claw of FIG. Partial side view of the main part of FIG. The same figure as FIG. 8 which shows the principal part at the time of making the nail | claw of the parent-child nail | claw of FIG. 7 wide Grasping force decrease diagram showing an example of the relationship between rotational speed and grasping force when grasping the outer diameter of the workpiece with the chuck of the hydraulic chuck Grasping force increase diagram showing an example of the relationship between rotation speed and grasping force when the workpiece is grasped by the inner diameter of the chuck. Diagram showing an example of the relationship between the force of the piston of the hydraulic chuck and the gripping force Diagram showing an example of the relationship between hydraulic pressure and gripping force of a hydraulic chuck

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Monitoring apparatus 2 Grasping force detection means 2a Strain gauge 2b Force sensor 3 Notification means 3a Light emitting diode 4 Control part 5 Calculation part 6 Memory | storage part 7 Operation panel 8 Power supply 21 Work target grasping means 21a Hydraulic chuck 22 Chuck main body 23 Back plate 24 Spindle 25 Spindle base 26 Master jaw 27 Claw 31 Draw pipe 32 Hydraulic cylinder 33 Piston 33 Cylinder W Workpiece

Claims (14)

  A workpiece to be processed by the plurality of claws of the workpiece grasping means comprising a chuck body attached to the tip of the spindle rotatably supported by the spindle stock, and a plurality of claws arranged to be openable and closable on the chuck body. A grasping force detecting means for detecting grasping force is provided, and the grasping force of the object to be processed by the object to be grasped by the object to be processed by comparing the detected value of the grasping force detected by the grasping force detecting means with a preset threshold value. A method of monitoring a processing object grasping means characterized by determining whether or not there is an abnormality and notifying an operator of an abnormality when it is determined that the grasping force is abnormal.   2. The monitoring method of a processing object grasping means according to claim 1, wherein when the threshold value is a lower limit value and the detected value is less than the threshold value, the grasping force is determined to be insufficient.   2. The monitoring method for a workpiece grasping means according to claim 1, wherein when the threshold value is an upper limit value and the detected value exceeds the threshold value, the grasping force is determined to be excessively abnormal.   The threshold value is an allowable range constituted by two of a lower limit value and an upper limit value, and when the detected value is outside the allowable range, it is determined that the grasping power is insufficient or excessively abnormal. Item 2. A method for monitoring a workpiece grasping means according to Item 1. A workpiece to be machined by a plurality of openable / closable jaws of a workpiece grasping means having a chuck body attached to the tip of a spindle rotatably supported by the spindle stock and a plurality of claws arranged to be openable and closable on the chuck body. Grasping force detecting means for detecting grasping force of an object;
A notification means for notifying an operator of an abnormality in grasping force of the workpiece by the plurality of claws;
A storage unit that stores a threshold value of the grasping force of the object to be processed by the plurality of nails and a calculation unit are stored, and the detection value of the grasping force that is sent from the grasping force detection unit by the calculation unit is stored in the storage unit. A control unit for operating the notification means when it is determined that there is an abnormality in the grasping force of the object to be processed by the object to be grasped by the object grasping means. A monitoring device for processing object grasping means characterized by having.   The said threshold value is a lower limit value, and the said control part is comprised so that it may be judged that the said grasping power is insufficient abnormality, when the said detected value is less than the said threshold value. Monitoring device for the workpiece grasping means.   The processing object grasping means according to claim 5, wherein the threshold value is an upper limit value, and the control unit determines that the grasping force is excessively abnormal when the detected value exceeds the threshold value. Monitoring device.   The threshold value is an allowable range constituted by two of a lower limit value and an upper limit value, and the control unit determines that the grasping power is insufficient or excessively abnormal when the detected value is outside the allowable range. The monitoring apparatus for a processing object grasping means according to claim 5.   The monitoring apparatus for a workpiece grasping means according to any one of claims 5 to 8, wherein the grasping force detecting means is provided on the claw.   9. The workpiece according to claim 5, wherein the plurality of claws are formed so as to be freely opened and closed by a driving force of an actuator as a driving source connected via a connecting member. Monitoring device for grasping means.   The monitoring device for a workpiece grasping means according to claim 10, wherein the actuator is a hydraulic cylinder.   The workpiece grasping means according to claim 10 or 11, wherein the grasping force detecting means is disposed on at least one of the plurality of claws, a connecting member, and an actuator. apparatus.   The monitoring apparatus for a processing object grasping means according to any one of claims 5 to 12, wherein the grasping force detecting means is a strain gauge. The said chuck | zipper main body is attached to the front-end | tip of the said main shaft through the attachment member, The said notification means is provided in this attachment member, The any one of Claim 5 thru | or 13 characterized by the above-mentioned. A monitoring device for the object grasping means.