JP2008207189A - Device and method for dressing welding electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the accuracy of judgement of the abnormality of a cutter in the cutting of a welding electrode. <P>SOLUTION: This invention relates to a device for dressing welding electrode for cutting the welding electrode by using a cutter 30 which is rotated at a prescribed rotational speed by a rotational driving means 32, and the device for dressing welding electrode includes a rotational speed detecting means 60 for detecting values related to the rotational speed of the cutter 30 during cutting, a load detecting means 62 for detecting the values related to load which is added to the rotational driving means 32 during cutting and a cutter abnormality judging means 68 for judging the abnormality of the cutter 30 when the values related to the rotational speed which is detected by the rotational speed detecting means 60 are rather small as compared with a prescribed lower limit value of the load, or the values related to the load which is detected by the load detecting means 62 are rather small as compared with a prescribed lower limit value of the load. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a welding electrode dresser device and a welding electrode dresser method for cutting a welding electrode used for spot welding with a cutter, and belongs to the technical field of detecting cutting abnormality.

  Conventionally, a welding electrode used for spot welding is periodically cut by a dresser device. Specifically, a part of the surface of the welding electrode used by the rotating cutter (a part that contacts during welding) is cut. This is performed to remove a part of the member to be welded and deposited on the surface. Thereby, a welding electrode is maintained in a substantially new state, and normal welding can be continued.

  In such a dresser device, if an abnormality of the cutter such as chipping of the cutter blade edge occurs, the welding electrode cannot be cut normally, so it is necessary to detect the abnormality of the cutter. For example, there is a dresser device described in Patent Document 1 that detects an abnormality of a cutter. This is because the rotation speed of the cutter is detected during cutting of the welding electrode, and when the detected rotation speed value is not between the upper limit value and the lower limit value, that is, when the rotation speed value is outside the normal range. Judged as abnormal.

JP 2005-125361 A

  However, as in Patent Document 1 described above, when the abnormality determination of the cutter is performed only with the rotation speed of the cutter, the cutter may be determined to be abnormal although it is not actually abnormal. This occurs because the load applied to the cutter varies during cutting, whether the cutter is normal or abnormal, thereby changing the rotational speed of the cutter. For example, when a part of the cutter blade edge moves from the convex part of the surface of the welding electrode to the concave part, the cutting resistance of the whole blade edge decreases, and as a result, the rotation speed of the cutter instantaneously increases and exceeds the upper limit value. Nevertheless, it may be determined as abnormal.

  Then, this invention makes it a subject to provide the welding electrode dresser apparatus which can perform abnormality determination of a cutter correctly.

  In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is a welding electrode dresser device that cuts a welding electrode using a cutter that is rotated at a predetermined rotational speed by a rotation drive means, Rotation speed detection means for detecting a value related to the rotation speed of the cutter in the middle, load detection means for detecting a value related to the load applied to the rotation drive means during cutting, and the rotation speed detected by the rotation speed detection means A cutter abnormality determining means for determining a cutter abnormality when a related value is smaller than a predetermined rotational speed lower limit value or when a load related value detected by the load detecting means is smaller than a predetermined load lower limit value; It is characterized by having.

  According to a second aspect of the present invention, in the welding electrode dresser device according to the first aspect, the number of times of cutting counted by the number of times of cutting the welding electrode and the number of times of cutting counted by the number of times of cutting of the welding electrode are increased. And a predetermined load lower limit value correcting means for reducing the predetermined load lower limit value as it goes down.

  Further, according to a third aspect of the present invention, in the welding electrode dresser device according to the first or second aspect, the load detecting means continuously detects a load related value smaller than the predetermined load lower limit value a predetermined number of times. When it does, it has an exchange notification means which notifies replacement of a cutter.

  In addition, the invention according to claim 4 is a welding electrode dresser method for cutting a welding electrode using a cutter rotated at a predetermined rotation speed by a rotation driving means, and relates to the rotation speed of the cutter during cutting. A rotational speed detecting step for detecting a value to be detected, a load detecting step for detecting a value related to a load applied to the rotational driving means during cutting, and a rotational speed related value detected in the rotational speed detecting step is a predetermined rotational speed. A cutter abnormality determining step of determining a cutter abnormality when the load-related value detected in the load detection step is smaller than a predetermined load lower limit value. .

  In addition, the invention according to claim 5 is the welding electrode dresser method according to claim 4, in which the number of times of cutting the welding electrode is counted, and the cutting that is counted in the number-of-cuts counting step. And a predetermined load lower limit correction step of decreasing the predetermined load lower limit as the number of times increases.

  In addition, the invention according to claim 6 is the welding electrode dresser method according to claim 4 or 5, wherein a load-related value smaller than the predetermined load lower limit value is continuously predetermined in the load detection step. A change notification step of notifying the replacement of the cutter when the number of times is detected is included.

  According to the first aspect of the present invention, during the cutting of the welding electrode, a value related to the rotation speed of the cutter and a value related to the load applied to the rotation driving means for rotating the cutter are detected and detected. When the rotational speed related value is smaller than the predetermined rotational speed lower limit value, or when the detected load related value is smaller than the predetermined load lower limit value, an abnormality of the cutter is determined. This improves the accuracy of abnormality determination compared to determining cutter abnormality when the detected rotational speed value is not between the upper limit value and lower limit value.In other words, a normal cutter is determined to be abnormal. Is suppressed.

  According to the second aspect of the present invention, the predetermined load lower limit value is corrected to be smaller as the number of times of cutting the welding electrode increases. This is because the load applied to the rotation driving means is reduced as the blade edge of the cutter is worn. That is, if the predetermined load lower limit value is held at a constant value, wear of the blade edge of the cutter may be detected as an abnormality of the cutter, and this is intended to prevent this.

  Further, according to the third aspect of the present invention, when a load-related value that is smaller than the predetermined load lower limit value is continuously detected a predetermined number of times, in other words, a load-related value that is smaller than the predetermined load lower limit value. When the value is cut continuously a predetermined number of times, the replacement of the cutter is notified. That is, it is determined that the cutting ability of the cutter has been lowered, in other words, that the cutter has a little remaining life, and a notification is given to replace the cutter with a new one in order to continue normal cutting. Thereby, it is possible to know the replacement timing of the cutter.

  In addition, according to the invention described in claim 4, during the cutting of the welding electrode, a value related to the rotation speed of the cutter and a value related to the load applied to the rotation driving means for rotating the cutter are detected, When the detected rotation speed related value is smaller than the predetermined rotation speed lower limit value or when the detected load related value is lower than the predetermined load lower limit value, the abnormality of the cutter is determined. Thereby, the accuracy of the abnormality determination is improved as compared with the case where the abnormality of the cutter is determined when the detected rotational speed value is not between the upper limit value and the lower limit value. That is, it is suppressed that a normal cutter is determined to be abnormal.

  In addition, according to the fifth aspect of the invention, the predetermined load lower limit value is corrected to be smaller as the number of cuttings of the welding electrode increases. This is because the load applied to the rotation driving means is reduced as the blade edge of the cutter is worn. That is, if the predetermined load lower limit value is held at a constant value, wear of the blade edge of the cutter may be detected as an abnormality of the cutter, and this is intended to prevent this.

  In addition, according to the invention described in claim 6, when a load-related value smaller than the predetermined load lower limit value is continuously detected a predetermined number of times, in other words, smaller than the predetermined load lower limit value. When cutting of the load related value is continuously performed a predetermined number of times, the replacement of the cutter is notified. That is, it is determined that the cutting ability of the cutter has been lowered, in other words, that the cutter has a little remaining life, and a notification is given to replace the cutter with a new one in order to continue normal cutting. Thereby, it is possible to know the replacement timing of the cutter.

  FIG. 1 shows a schematic configuration of a spot welding apparatus incorporating a welding electrode dresser apparatus according to an embodiment of the present invention.

  A spot welding apparatus denoted by reference numeral 10 in the figure controls a spot welding robot 12, a dresser apparatus 16 that periodically cuts the welding electrodes 14a and 14b of the spot welding robot 12, and a spot welding robot 12 and a dresser apparatus 16. The controller 18 is configured.

  The spot welding robot 12 has a robot arm structure, and a welded portion to be welded is sandwiched from the front and back by two welding electrodes 14a and 14b, and a current flows between the two welding electrodes 14a and 14b via the welded portion. It is comprised so that a to-be-welded part may be welded by flowing.

  The dresser device 16 is for periodically cutting the welding electrodes 14a and 14b in order to maintain the welding electrodes 14a and 14b of the spot welding robot 12 in a substantially new state. The reason for cutting regularly is that, if the welding electrodes 14a and 14b are used many times, a part of the welding target part to be welded (for example, plating to be welded) adheres to and accumulates on the surface of the welding electrode 14a and 14b. This is because there are cases where welding cannot be performed normally.

  The dresser device 16 is installed within the operating range of the spot welding robot 12, that is, within the range where the two welding electrodes 14a and 14b can reach.

  Details of the dresser device 16 will be described with reference to FIGS.

  As shown in FIGS. 2 and 3, the dresser device 16 roughly includes a cutter 30 for cutting the tips of the welding electrodes 14 a and 14 b, a drive motor 32 for rotationally driving the cutter 30, and the drive motor 32 to the cutter 30. A gear unit 34 for transmitting rotational driving force to the blade, a bracket 30 for supporting the cutter 30, the drive motor 32, and the gear unit 34, and a plurality of members disposed between the bracket 36 and a base (not shown). And a spring 38.

  As shown in FIG. 4, the cutter 30 is a substantially cylindrical body having a rotation center line CL, and includes a dress blade 40 that cuts the welding electrodes 14 a and 14 b and a holder 42 that holds the dress blade 40.

  The dressing blade 40 has a shape capable of cutting the tips of the welding electrodes 14a and 14b into a predetermined shape (in this embodiment, a cylindrical shape and a chamfered portion at the tip), and has four cutting edges 44a. To 44d. As shown in FIG. 2, the cutter 30 abuts so that the tips of the two welding electrodes 14 a and 14 b moving along the rotation center line CL sandwich the dress blade 40 (direction perpendicular to the rotation center line CL). 5), the four cutting edges 44a to 44d are configured to be capable of cutting both the two welding electrodes 14a and 14b at the same time by being rotationally driven by the drive motor 32. Strictly speaking, the four cutting edges 44a to 44d do not cut the two welding electrodes 14a and 14b at the same time, but in one direction around the rotation center line CL by the drive motor 32 (rotation direction A in FIG. 4). When the cutter 30 is rotated, the cutting edge 44a cuts the welding electrode 14a and the cutting edge 44c cuts the welding electrode 14b. On the other hand, when the cutter 30 is rotated in the other direction (rotation direction B in FIG. 4), the cutting edge 44b cuts the welding electrode 14a and the cutting edge 44d cuts the welding electrode 14b. The welding electrodes 14a and 14b cut by such a cutter 30 have a shape in which a new chamfered portion from which deposits are removed is formed.

  The drive motor 32 is supported by the bracket 36 so that the direction of the output shaft 46 shown in FIG. 3 is parallel to the direction of the rotation center line CL of the cutter 30.

  The gear unit 34 is for drivingly connecting the drive motor 32 and the cutter 30, and has a plurality of gears 48a to 48c therein as shown in FIG. The gear 48 a is a drive gear attached to the output shaft 46 of the drive motor 32. The gear 48 c is a gear for rotating the cutter 30 and rotates around the rotation center line CL of the cutter 30. The gear 48c and the cutter 30 are drivingly connected so as to be detachable. The gear 48b is a gear for transmitting a rotational driving force from the gear 48a to the gear 48c.

  The bracket 36 is for integrally supporting the cutter 30, the drive motor 32, and the gear unit 34.

  The plurality of springs 38 support the bracket 36. That is, the bracket 36 is supported so as to be movable up and down. The reason for this is that when the welding electrodes 14a and 14b are cut and the tips thereof are pressed against the dressing blade 40 of the cutter 30, the force with which one welding electrode 14a presses the dressing blade 40 and the other welding electrode 14b This is because the force for pressing the dress blade 40 is the same. If the forces are not the same, the cutter 30 cannot normally cut the two welding electrodes 14a and 14b at the same time. Such a force is called a gun pressure.

  The control device 18 is configured to control the spot welding robot 12 and the dresser device 16, strictly speaking, the drive motor 32.

  The control device 18 controls the spot welding robot 12 to execute spot welding, and periodically, for example, when spot welding is executed a predetermined number of times, the two welding electrodes 14a of the robot 12 as shown in FIG. 14 b is configured to control the robot 12 so as to contact the dress blade 40 of the cutter 30.

  As shown in FIG. 7, the control device 18 controls the spot welding robot 12 so that the gun pressing force is constant when the welding electrodes 14 a and 14 b are cut. In addition, the control device 18 executes control for rotating the drive motor 32 at a predetermined constant rotational speed V. Strictly speaking, after the drive motor 32 is rotated at the rotation speed V in the normal rotation direction for a predetermined time, the control is performed at a rotation speed −V in the reverse rotation direction for a certain time with an intermittent period. Repeat control is executed. In addition, as shown in the figure, the reason why the drive motor 32 is rotated even after the cutting is completed is to remove the chips in the cutter 30 by rotating them to the outside.

  Further, as shown in FIG. 8, the control device 18 determines the abnormality of the cutter 30, as shown in FIG. 8, the rotational speed detection unit 60, the load detection unit 62, the rotational speed abnormality detection unit 64, the load abnormality detection unit 66, and the cutter abnormality. The determination unit 68 includes a load abnormality number counting unit 70, a cutting number counting unit 72, a load lower limit correction unit 74, a cutter abnormality notification unit 76, a cutter replacement determination unit 78, a cutter replacement notification unit 80, and a storage unit 82. These will be described in the description of the abnormality determination flow of the cutter 30 executed by the control device 18 described later.

  The cutter 30 abnormality determination method executed by the control device 18 will be described.

  The control device 18 detects the rotational speed of the drive motor 32 of the dresser device 40 and the load applied to the drive motor 32 during cutting of the welding electrodes 14a and 14b, and the cutter 30 is controlled based on the detected rotational speed and load. It is configured to determine an abnormality.

  For example, when the drive motor 32 is an AC servo motor, the value of the rotation speed can be known from the rotation frequency output from the motor (the frequency of the signal indicating the number of rotations), and the load is determined from the load current input to the motor. I can know.

  FIG. 9 shows changes in the rotation frequency and load current during cutting when the drive motor 32 is an AC servomotor. Moreover, the change shown in this figure is a change in a mountain of changes in the rotational speed shown in FIG.

  As shown in FIG. 9A, when the cutter 30 is normal, the rotational frequency during cutting is the rotational frequency corresponding to the predetermined constant rotational speed V described above except at the start of cutting and after the end of cutting. Hereinafter, this is referred to as “set frequency”. On the other hand, the load current fluctuates at the start of cutting in order to maintain the rotation frequency at the set frequency, but remains constant and stable during cutting.

  On the other hand, as shown in FIG. 9B, when the cutter 30 is abnormal I, the load current is being cut even if the load current exceeds the normal value of the cutter 30 (see FIG. 9A) and is maximized. The rotation frequency of is smaller than the set frequency. Such an abnormality occurs, for example, when the cutting edge of the dressing blade 40 of the cutter 30 is chipped and the cutting edge portion that is cut and sharpened bites into the welding electrodes 14a and 14b.

  On the other hand, as shown in FIG. 9C, when the cutter 30 is abnormal II, the rotation frequency is maintained at the set frequency, but the load current is smaller than when the cutter 30 is normal. Such an abnormality occurs, for example, when the dressing blade 40 of the cutter 30 is chipped and the cutting resistance of the portion where the blade tip is chipped decreases.

  Therefore, if the threshold value is appropriately set for each of the rotation frequency and the load current, the abnormality determination of the cutter 30 can be executed. For example, as shown in FIG. 9, the period from when cutting starts until the rotational frequency reaches the set frequency until the end of cutting is the period during which the abnormality of the cutter 30 is determined (the rotational frequency of the normal cutter 30 is the set frequency). The rotation frequency threshold value and the load value threshold value are set at positions where it can be determined whether the cutter 30 is normal or abnormal during this period.

  For example, the rotational frequency threshold value is set to a value slightly smaller than the set frequency in consideration of the set frequency value or motor response. The threshold value of the load current is set to the minimum load current value within the determination period when the cutter 30 is normal.

The threshold value can be said to be the lower limit value of the range in which the cutter 30 is normal, that is, the cutting is normally performed. Hereinafter, the lower limit value of the rotation frequency is referred to as “rotational speed lower limit value”, and the lower limit value of the load current is referred to as “load lower limit value”. For example, when the output of the AC servo motor is 0.5 kW and the rotation speed at the time of cutting is set to 1500 to 1800 rpm, the rotation speed lower limit value is 50 to 60 Hz and the load lower limit value is 2.26 to 2.3 A. Is set.

  The control device 18 starts monitoring the rotational frequency of the drive motor 32 and the load current of the motor from the start of cutting, and performs an abnormality determination of the cutter 30 after the start of cutting and the rotational frequency reaches the set frequency. During the abnormality determination (during the determination period), when the rotation frequency becomes smaller than the rotation speed lower limit value or when the load current becomes smaller than the load lower limit value, the control device 18 has an abnormality in the cutter 30. Is determined.

  An advantage of the abnormality determination of the cutter 30 by such a method is that determination of a normal cutter as abnormal is suppressed, and determination accuracy is improved.

  When the rotation speed of the cutter during cutting is not between the upper limit value and the lower limit value as in the above-described embodiment, it is determined that the cutter is abnormal, that is, when the rotation speed is not in the normal range, it is determined that the cutter is abnormal. Even with a normal cutter, the rotational speed may be outside the normal range due to load fluctuations that occur during cutting. If the normal range is expanded as a countermeasure, an abnormal cutter may be determined to be normal this time. Considering this, it is difficult to set a range in which the cutter can be said to be normal.

  However, in this embodiment, a lower limit is set for each of the rotation frequency value and the load current value, and when the at least one value is smaller than the corresponding lower limit value, it is determined that the cutter is abnormal. not exist. Accordingly, if the lower limit value is set at a position where a value smaller than this is apparently an abnormality of the cutter, the abnormality of the cutter can be accurately determined. The reason why there is no need to provide an upper limit value is to perform cutter abnormality determination using two parameters, that is, a rotation frequency value and a load current value.

  From here, an example of the flow of control for determining abnormality of the cutter 30 performed by the control device 18 will be described. The description will be made with reference to the block diagram of the control device 18 shown in FIG. 8 and the flow shown in FIG. For ease of explanation, the example here is an example in which the cutter 30 rotates in only one direction and cuts the welding electrodes 14a and 14b.

  The flow shown in FIG. 10 is a flow that starts when the control device 18 starts to cut the welding electrodes 14 a and 14 b by the dresser device 16. This flow is also a process chart for detecting an abnormality of the cutter in the welding electrode dresser method.

  First, in S100 (process), the control device 18 controls the spot welding robot 12 and the drive motor 32 of the dresser device 16 to start cutting the welding electrodes 14a and 14b.

  Next, in S110 (process), the control device 18 determines whether or not the cutter 30 that is currently used is a cutter that has been used in the immediately preceding cutting, that is, whether or not it is a new cutter. This is because the number of times of cutting of the cutter is counted as will be described later, and it is necessary to reset the number of times of cutting when the cutter is replaced with a new cutter. If it is a new cutter, the process proceeds to S120. Otherwise, the process proceeds to S130.

  Whether or not the cutter is a new cutter is determined with reference to cutter information 84 stored in the storage unit 82 of the control device 18, for example, as shown in FIG. The cutter information 84 includes information on a plurality of cutters used in the past, and the cutter currently attached to the dresser device 16 does not match the latest cutter written in the cutter information 18 Is determined to be a new cutter. The cutter information 84 is configured such that new cutter information is written and updated each time the cutter is replaced.

  In S120 (process), the control device 18 resets the number of cuttings 86 held as information in the storage unit 82, a load lower limit 88 described later, and a load abnormality count 90 described later (the load lower limit 88 is an initial value). Return to.)

  In S130 (process), the rotation speed detection unit 60 of the control device 18 starts to detect the rotation speed of the drive motor 32 (the rotation frequency in the above example in which the drive motor 32 is an AC servomotor). In addition, the load detection unit 62 starts detecting a load applied to the drive motor 32 (load current in the above example in which the drive motor 32 is an AC servomotor).

  In subsequent S140 (process), the load abnormality detection unit 66 of the control device 18 compares the load lower limit value 88 stored in the storage unit 82 with the load value detected by the load detection unit 62, and the detected load value is determined. It is determined whether or not the load lower limit value 88 is greater. When the detected load value is larger than the load lower limit value (when the load is normal), the process proceeds to S150. Otherwise (when the load is abnormal), the process proceeds to S160.

  In S150 (step), the rotation speed abnormality detection unit 64 of the control device 18 sets a preset rotation speed value (rotation speed lower limit value) (in the above example in which the drive motor 32 is an AC servo motor). The set rotational frequency) is compared with the rotational speed detected by the rotational speed detector 60, and it is determined whether or not the detected rotational speed value is larger than the rotational speed lower limit value. When the detected rotation speed value is larger than the rotation speed lower limit value (when the rotation speed is normal), the process proceeds to S170. Otherwise (when the rotational speed is abnormal), the process proceeds to S180.

  In S160 (process), the load abnormality frequency counting unit 70 of the control device 18 increments the load abnormality frequency 90 held as information in the storage unit 82 by one. Details of the load abnormality frequency will be described later. The process proceeds to S180.

  In S180 (process), the cutter abnormality determination unit 68 of the control device 18 determines that there is an abnormality in the cutter 30 when at least one of a load abnormality or a rotation speed abnormality is determined. In response to this, the cutter abnormality notification unit 76 notifies the abnormality of the cutter 30 via a cutter abnormality notification device (for example, a speaker or a lamp) 52 outside the control device 18. Proceed to S190.

  In S170 (process), the control device 18 determines the end of cutting. When the cutting ends, the process proceeds to S200. Otherwise, the process returns to S140.

  In S190 (process), the control device 18 determines the end of cutting. When the cutting ends, the process proceeds to S210. Otherwise, S190 is looped.

  In S <b> 200 (process), the control device 18 resets the load abnormality count 90 held in the storage unit 82. The load abnormality frequency 90 will be described later.

  In S210 (process), the cutting frequency counting unit 72 of the control device 18 increments the cutting frequency 86 held as information in the storage unit 82 by one.

  In S220 (process), the load lower limit correction unit 74 of the control device 18 uses the load lower limit value 88 stored as information in the storage unit 82, and also holds the number of cuttings 86 and the number of cuttings-load lower limit value map. 92, the value is corrected to a small value.

  The reason for correcting the load lower limit value is that the load applied to the drive motor 32 is reduced as the cutting edge of the dressing blade 40 of the cutter 30 is worn. When the cutting edge is worn, the cutting resistance is reduced, for example, because it becomes impossible to cut deeply into the welding electrodes 14a, 14b, and the load applied to the drive motor 32 is thereby reduced. That is, if the load lower limit value is held at a constant value, wear of the cutting edge of the dressing blade 40 may be detected as an abnormality of the cutter 30, and this is to prevent this.

  The number-of-cuts-load lower limit map 92 is a map in which, for example, as shown in FIG. Such a map is experimentally obtained in advance.

  In S230 (process), the cutter replacement determination unit 78 of the control device 18 determines whether or not the load abnormality frequency 90 is 5 with reference to the load abnormality frequency 90 stored as information in the storage unit 82. That is, it is determined whether or not cutting that causes the load applied to the drive motor 32 to be smaller than the load lower limit value has been continuously executed five times.

  When the load abnormality frequency is 5, the cutting edge of the dressing blade 40 is worn to some extent and the cutting ability is lowered, and the surface of the welding electrodes 14a and 14b may not be sufficiently cut in the subsequent cutting. Therefore, it is necessary to replace with a new cutter. That is, counting the number of load abnormalities is executed to detect that the cutter 30 is at the end of its life, in other words, to know the cutter replacement timing.

  If it is determined in S230 (step) that the load abnormality count is 5 (when the cutter is at the end of its life), the process proceeds to S240. Otherwise, this flow ends.

  In S240 (process), the cutter replacement notification unit 80 of the control device 18 notifies the replacement of the cutter via the external cutter replacement notification unit 54. Then, this flow ends.

  While the present invention has been described with reference to the above-described embodiment, the present invention is not limited to this.

  For example, in the above-described embodiment, there are two welding electrodes, each of which has a cylindrical shape and is provided with a chamfered portion at the tip thereof, and the cutter can be cut into that shape and is correct. Although cutting is possible by rolling and reverse rotation and two electrodes are cut simultaneously, the present invention is not limited to this. In a broad sense, the present invention is applied to a dresser apparatus and a dresser method for cutting a welding electrode with a cutter rotated by a rotation driving means.

  In the above-described embodiment, the rotation driving means for rotating the cutter is an AC servo motor, but the present invention is not limited to this. In a broad sense, the present invention only needs to be a rotational drive unit that can rotate the cutter at a constant rotational speed during cutting, and may be a motor other than a servo motor. In this case, for example, it is necessary to provide a sensor that detects the rotation speed of the output shaft of the motor and a device that can control the current input to the motor so that the rotation speed detected by the sensor is constant.

  Furthermore, it may be determined whether or not the cutter is abnormal by confirming whether or not the welding electrode has been normally cut by the cutter.

  For example, after the cutting by the cutter is completed, the welding electrode is brought into contact with a conductive member (in the above-described embodiment, for example, another welding electrode), a current is passed between them, the contact resistance value is measured, and the contact resistance value is When it is larger than the normal contact resistance value (value when the welding electrode is normally cut), the cutter abnormality may be determined. In this case, the accuracy of cutter abnormality determination is further improved.

It is a figure which shows schematic structure of the spot welding apparatus incorporating the welding electrode dresser apparatus which concerns on one Embodiment of this invention. It is a front view of a dresser apparatus. It is a top view of a dresser device. It is a perspective view of a cutter. It is a figure which shows the two welding electrodes which are contact | abutting to the dress blade. It is a figure which shows the inside of a gear unit. It is a figure which shows the change of the gun pressing force, and the change of the rotational speed of the drive motor by the control which a control apparatus performs. It is a figure which shows the structure of the control apparatus relevant to the abnormality determination of a cutter. It is a figure which shows the relationship between the state of a cutter, a rotation frequency, and load current. It is a flow which shows an example of the flow of control for judging abnormality of the cutter which a control device performs. It is a figure which shows an example of the frequency | count of cutting-load lower limit map.

Explanation of symbols

30 cutter 32 rotation drive means (drive motor)
60 Rotational speed detection means (rotational speed detector)
62 Load detection means (load detection unit)
68 Cutter abnormality determining means (cutter abnormality determining unit)

Claims (6)

A welding electrode dresser device that cuts a welding electrode using a cutter that is rotated at a predetermined rotational speed by a rotation driving means,
A rotational speed detecting means for detecting a value related to the rotational speed of the cutter during cutting;
Load detecting means for detecting a value related to a load applied to the rotation driving means during cutting;
When the rotational speed related value detected by the rotational speed detecting means is smaller than a predetermined rotational speed lower limit value, or when the load related value detected by the load detecting means is smaller than a predetermined load lower limit value, A welding electrode dresser device comprising cutter abnormality determination means for determining abnormality. The welding electrode dresser device according to claim 1,
Cutting frequency counting means for counting the number of times the welding electrode has been cut;
A welding electrode dresser apparatus comprising: a predetermined load lower limit value correcting unit that decreases the predetermined load lower limit value as the number of cuttings counted by the cutting number counting unit increases. The welding electrode dresser device according to claim 1 or 2,
A welding electrode dresser apparatus, comprising: a change notification means for notifying the replacement of a cutter when the load detection means detects a load related value smaller than the predetermined load lower limit value continuously a predetermined number of times. A welding electrode dresser method for cutting a welding electrode using a cutter rotated at a predetermined rotational speed by a rotation driving means,
A rotational speed detection step for detecting a value related to the rotational speed of the cutter during cutting;
A load detection step of detecting a value related to a load applied to the rotation driving means during cutting;
When the rotation speed related value detected in the rotation speed detection step is smaller than a predetermined rotation speed lower limit value, or when the load related value detected in the load detection step is smaller than a predetermined load lower limit value, The welding electrode dresser method characterized by including the cutter abnormality determination process which determines abnormality of a cutter. The welding electrode dresser method according to claim 4,
A cutting frequency counting process for counting the number of times the welding electrode has been cut;
A welding electrode dresser method comprising: a predetermined load lower limit correction step of decreasing the predetermined load lower limit as the number of cuts counted in the cutting count counting step increases. In the welding electrode dresser method according to claim 4 or 5,
A welding electrode dresser method comprising a replacement notification step of notifying the replacement of a cutter when a load-related value smaller than the predetermined load lower limit value is continuously detected a predetermined number of times in the load detection step.

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