JP2000343280A - Method and device for controlling welding positioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently execute the setting work of groove dimensions with inexpensive and simplified equipment and, moreover, to enhance reliability by improving the dimensional accuracy. SOLUTION: Based on the detection data of the thrust and travel of a moving frame 8, first, the moving frame 8 is advanced to the position where the mutual end faces of a main body work 2 and bracket work 3 are pushed against each other. Next, the moving frame 8 is moreover retreated till the thrust of the moving frame 8 becomes zero and, after that, the moving frame is moreover retreated till the amount of travel of the moving frame 8 reaches a 1st set value. Next, till the amount of travel reaches the 2nd set value, the moving frame 8 is moreover retreated and, lastly, the moving frame 8 is advanced till the thrust becomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a control apparatus for a weld positioner for setting a groove size of a butt weld.

[0002]

2. Description of the Related Art When manufacturing arms, booms, and the like of construction machines and cranes, butt welding between a main body work and a bracket work is often performed. This butt welding is performed by holding both works at a predetermined groove size (root gap) at the butt portion, and clamping both works in this state. Here, the setting of the groove dimension is usually performed by using a contact gauge corresponding to the dimension, or by measuring the dimension with a caliper or the like by an operator. In the case of using a contact gauge, there are a method in which an operator manually performs the operation and a method in which the contact gauge is operated by a hydraulic cylinder or an air cylinder.

FIGS. 8 (a) and 8 (b) show a method of setting a groove size using a conventional contact gauge operated by a hydraulic cylinder. In this groove dimension setting method, a contact gauge 53 is provided between the main body work 51 and the bracket work 52 in a state of being separated from each other.
Is inserted by the operation of the hydraulic cylinder 54 so that the tip of the contact gauge 53 contacts the backing material 55. In this state, the bracket work 52 is advanced toward the main body work 51, and the bracket work 52 is contacted with the contact gauge 55. The procedure of pressing against the main body work 51 via 53 and then pulling out the contact gauge 53 is adopted. The backing material 55 may be provided integrally with the bracket work 52 in some cases.

[0004]

However, in the above-described groove dimension setting method using a contact gauge, it is necessary to manufacture a contact gauge corresponding to each work shape, and the mounting position also changes. When operating the contact gauge manually, the operation is extremely complicated and time-consuming, and when operating automatically, it is necessary to perform setup changes and adjustments for each work, which leads to a rise in equipment costs. There is a problem. Further, in the case of a box-shaped or pipe-shaped work as shown in FIG. 8, if the contact gauge is attached to only one outside position, the work is bent at the time of pressing the work, and uniform groove dimensions cannot be obtained. However, there is also a problem that it is necessary to attach a contact gauge to a plurality of locations on the circumference, and the equipment becomes complicated.

Further, in the case of this setting method, gauges and their driving mechanisms exist near the welding place,
In addition to problems such as the occurrence of defects due to the attachment of spatter to these gauges and the increase in maintenance frequency, and the need for a large amount of space for the contact gauge operation device, this operation device etc. operates the welding torch. There is a problem that the degree of freedom is hindered.

In addition, there is also a problem that the insertion resistance at the time of contact between the two works fluctuates due to dimensional variations of the works. In other words, when the work is pressed against the contact gauge, a large slide thrust is required because it is necessary to overcome the insertion resistance and press strongly.However, when the slide thrust is increased in this way, elastic deformation occurs on the contact gauge and the work. This causes a problem that the groove dimension is reduced when the contact gauge is removed due to the deformation.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the work of setting a groove dimension can be efficiently performed by inexpensive and simplified equipment. It is an object of the present invention to provide a control method and a control device for a welding positioner, which can improve the accuracy and the reliability.

[0008]

In order to achieve the above object, a method for controlling a welding positioner according to a first aspect of the present invention includes a welding positioner having a fixed frame and a moving frame. A method of controlling a welding positioner for setting a groove dimension of a butt weld portion between a first work and a second work mounted on a moving frame to a predetermined value, comprising: Based on the detection data, the moving frame is first advanced to a position where the end faces of the first work and the second work are pressed against each other, and then the moving frame is retracted until the thrust of the moving frame becomes zero. The moving frame is further retracted until the moving amount of the moving frame reaches the first set value, and then the moving frame is moved backward until the moving amount reaches the second set value. The moving frame is further retracted, is characterized in that for advancing the moving frame to the end on the thrust becomes zero.

In the method for controlling a welding positioner according to the first aspect of the present invention, the groove size of the butt weld portion between the first work mounted on the fixed frame and the second work mounted on the moving frame is movable. It is set using the detection data of the thrust and the movement amount of the frame. In setting the groove dimensions, first, the moving frame is advanced to a position where the end faces of the first work and the second work are pressed against each other,
Next, the moving frame is retracted until the thrust of the moving frame becomes zero, and thereafter the moving frame is further retracted from the position where the thrust becomes zero until the moving amount of the moving frame reaches the first set value. , Then the amount of movement is second
The moving frame is further retracted until the set value is reached, and finally the moving frame is advanced until the thrust becomes zero. Thus, the workability of setting the groove size of the butt weld can be improved. Further, since there is no need to insert a contact gauge between the first work and the second work as in the related art, the worker can work away from the work and pinch his hand between the works. There is no danger.

Next, a welding positioner control apparatus according to a second aspect of the present invention for specifically realizing the welding positioner control method according to the first aspect of the present invention includes a welding positioner having a fixed frame and a moving frame. A control device for a welding positioner for setting a groove dimension of a butt welding portion between a first work mounted on a frame and a second work mounted on a moving frame to a predetermined value, wherein the moving frame is fixed. Moving means for moving in the direction of approaching / separating from the frame, thrust detecting means for detecting a thrust of the moving frame, moving amount detecting means for detecting the moving amount of the moving frame, and the moving frame by the moving means Control means for controlling the movement of the thrust force, the control means, the thrust detected by the thrust detection means until the thrust reaches a predetermined threshold The moving frame is moved in the approaching direction, and then the moving frame is moved in the separating direction until the thrust becomes zero. Thereafter, the moving amount detected by the moving amount detecting means reaches a first set value. The moving frame is further moved in the separating direction until the moving amount reaches a second set value, and the moving frame is further moved in the separating direction until the moving amount reaches a second set value. The moving means is controlled so as to move in the approach direction.

In the control apparatus for a welding positioner according to the second aspect of the present invention, the moving means for moving the moving frame in a direction close to or away from the fixed frame is controlled by the control means, so that the moving frame is mounted on the fixed frame. A groove size of a butt weld between the first work and the second work mounted on the moving frame is set. The control of the moving means by the control means is performed as follows.
First, the moving frame is moved in a direction close to the fixed frame until the thrust detected by the thrust detecting means reaches a predetermined threshold, and then the moving frame is moved in the separating direction until the thrust of the moving frame becomes zero. Thereafter, the moving frame is further moved away from the position where the thrust becomes zero until the moving amount of the moving frame reaches the first set value, and then the moving frame is moved until the moving amount reaches the second set value. The moving frame is further moved in the separating direction, and finally the moving frame is moved in the approaching direction until the thrust becomes zero.

According to the present invention, the setting of the groove size for various types of workpieces can be easily performed by data processing, so that the workability and the setting accuracy can be improved. Further, as compared with the conventional method of moving the contact gauge by automatic operation, the equipment can be simplified and the equipment can be inexpensive, and the welding work range can be widened and the degree of freedom in welding can be increased. Further, it is not necessary to prepare various kinds of contact gauges and gauge attaching means corresponding to various kinds of works, and it is possible to easily cope with a change of works. Furthermore, since the thrust detecting means and the moving amount detecting means, which are the main components of the present invention, can be placed at a position far from the welding place not affected by spatter, a highly reliable apparatus can be obtained. .

In the second invention, the predetermined threshold value is a value sufficiently larger than a maximum value of the insertion resistance between the first work and the second work, and the first set value is a value of the butt weld portion. The second set value is a value obtained by multiplying the thrust when the movement amount reaches the first set value by a predetermined elastic strain constant. preferable.

It is preferable that the moving means moves the moving frame by a ball screw driven by a motor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of a control method and a control device of a welding positioner according to the present invention will be described with reference to the drawings.

FIG. 1 is an overall structural view of a welding positioner according to one embodiment of the present invention. FIG.
FIG. 2A shows a work shape taking an arm (or boom) of a hydraulic shovel as an example, and FIG. 2B shows a cross-sectional view of a butt weld. This embodiment shows an example applied to the case where butt welding is performed manually or by a robot.

As shown in FIG. 2A, the arm 1 of the present embodiment has a rectangular frame-shaped cross section, and a bracket work (second work) is formed with respect to a main body work (first work) 2. 3) It is formed by moving 3 in the direction of arrow A, inserting it, and welding the butted portion. At this time, welding is performed in a state where a groove dimension (root gap) g is secured at the butted portion. Here, what is indicated by reference numeral 4 is a backing material, and the backing material 4 may be integrated with the bracket work 3 in some cases.

Each of the workpieces 2 and 3 is mounted on a welding positioner 5 as shown in FIG. 1, and a groove size g is set by the welding positioner 5, and after this setting, welding is performed. You. The welding positioner 5 of the present embodiment is a welding positioner that is used for both temporary attachment and permanent attachment.

In the welding positioner 5, a base frame 6 is provided, and a fixed frame 7 and a moving frame 8 are provided on the base frame 6 so as to face each other. The fixed frame 7 has a turning face plate 9 on the side facing the moving frame 8, and the turning face plate 9 can be turned in the front-rear direction (the direction of arrow B in FIG. 1) by a turning mechanism (not shown). ing. Similarly, the moving frame 8 has a turning face plate 10 on the side facing the fixed frame 7, and the turning face plate 10 can be turned in the front-rear direction (the direction of arrow C in FIG. 1) by a turning mechanism (not shown). It has been like that.

A bracket 11 having a substantially L-shape in side view is attached to the fixed-side rotating face plate 9.
The work fixing jig 12 is mounted thereon, and the rear end of the main body work 2 is supported by the work fixing jig 12. Also, in the base frame 6,
A work support jig 13 that supports the front end of the main body work 2 is provided to be vertically movable by a vertical movement mechanism 14. In this manner, the main body work 2 is supported by the work fixing jig 12 and the work support jig 13 while adjusting the height position on the front end side. The work supporting jig 13 is retracted downward when the temporary attachment of the work to be welded is completed. On the other hand, a bracket 15 having the same structure as that of the fixed side is attached to the movable-side rotating face plate 10, and work fixing jigs 16 and 17 are provided on the rear side and the front side of the bracket 15, respectively. The bracket work 3 is supported by these work fixing jigs 16 and 17.

The moving frame 8 is mounted on a slide rail 18 with little friction, and can be moved in the front-rear direction (direction of arrow D) by moving means. In order to move the moving frame 8, a bracket 19 protrudes from the lower surface of the moving frame 8, and a ball screw 21 is engaged with a ball screw nut 20 mounted on the bracket 19. The moving frame 8 is moved forward and backward through the ball screw nut 20 by rotating the ball screw 21 forward and backward by the servo motor 22.

The servo motor 22 is provided with a rotation angle detecting encoder (not shown), whereby the moving amount of the ball screw 21, that is, the moving amount of the moving frame 8 is detected. I have. FIG.
As shown in FIG. 7, a strain gauge 23 for detecting distortion is attached to the surface of the bracket 19, whereby the thrust of the ball screw 21, that is, the thrust of the moving frame 8 is detected.

Data on the amount of movement of the ball screw 21 from the encoder and data on the thrust of the ball screw 21 from the strain gauge 23 are input to a controller (control means) 24. The controller 24
A required operation is executed based on these input data, and a control signal is output to the servomotor 22 based on the operation result. Thus, the rotation of the servo motor 22 is controlled, and the forward and reverse rotation of the ball screw 21, in other words, the moving frame 8
Is controlled.

Next, a control mode of the welding positioner 5 in this embodiment for setting the groove size to a predetermined value will be described with reference to a flowchart shown in FIG.

S1: First, the main body work 2 and the bracket work 3 are set on predetermined portions of the fixed frame 7 and the moving frame 8, respectively, and they are centered and fixed (FIG. 5 (a)).
reference). When automatic operation is started in this state, the servo motor 22 is driven, the ball screw 21 rotates in the forward direction, the moving frame 10 moves in the forward direction via the ball screw nut 20 and the bracket 19, and the bracket work 3 is moved. Is inserted into the main body work 2. In this case, since the main body work 2 and the bracket work 3 are centered and mounted so as to be insertable, the backing material 4 mounted on the bracket work 3 side is inserted into the main body work 2. Then, the end face of the bracket work 3 is pressed against the end face of the main body work 2 (see FIG. 5B). When the moving frame 8 moves, the moving amount (the ball screw 21)
The thrust of the moving frame 8 (thrust of the ball screw 21) is detected from the amount of strain of the strain gauge 23.

S2: The thrust of the ball screw 21 obtained from the output of the strain gauge 23 is set to a predetermined threshold value (set to a value sufficiently larger than the maximum value of the insertion resistance of both works 2 and 3). It is determined whether or not r has been reached. 6A and 6B show the movement amount p of the ball screw 21.
The relationship between the force and the thrust q (in the case of a hard fit) is shown. As is clear from FIG. 5, the two works 2 and 3 are separated from each other as shown in FIG.
Both work 2,3 as shown in (b) is inserted when moving up against which the state pressing the end faces, thrust q of the ball screw 21, shown by arrow P ₁ in FIGS. 6 (a) increasing manner, gradually increases in accordance with the movement amount p of the ball screw 21 is increased, after the end faces of the two workpieces 2 and 3 are collides is sharply at upward-sloping curve as indicated by arrow P ₂ I do. Thereafter, the thrust q at point _{P 3} reaches the threshold r. If the workpieces 2 and 3 and the respective parts of the welding positioner 5 are rigid bodies, when the end faces of the workpieces 2 and 3 come into contact with each other, the curve of the thrust q rises almost vertically. And the like are distorted by thrust, resulting in an oblique rising curve.

S3 and S4: When the thrust q reaches the threshold r,
Judge that the pressing of both works 2 and 3 is completed,
Stop the rotation of 1. Next, the ball screw 21 is rotated in the reverse direction. This reverse rotation, thrust q as indicated by arrow P ₄ goes rapidly drops.

S5 to S6: It is detected whether or not the output of the strain gauge 23, that is, the thrust q of the ball screw 21 has become zero, and the ball screw moving position (slide position) when it reaches zero, that is, the point P Store the ₅ positions.

S7: The thrust q of the ball screw 21 becomes zero.
Position (point P₅The ball screw 21 is further rotated from the position
Then, the thrust q becomes a negative value, and this thrust q
P₆, P ₇Moving frame while changing as shown by
8 retracts and the end faces of the workpieces 2 and 3 are separated from each other.
To go. By detecting the amount of movement at this separation,
P ₅At a position separated by the groove dimension g to be secured from the position
That is, point P₈Is determined.

S8: Moving frame (slide) 8 is point P
_When the number reaches ₈ , the elastic strain amount h is calculated by the following formula based on the preset work and the elastic strain constant (spring-back coefficient) of the positioner device. The amount h, in other words, the point P ₉
The moving frame 8 is further retracted until the position is reached. Incidentally, this point P _9, the desired groove size g indicates the position obtained when zero thrust q. Here, the elastic strain constant can be easily obtained from the diagram by recording the ball screw thrust and the amount of movement using an XY plotter or the like during operation of the actual machine. Alternatively, the actual machine may be operated two or three times to find a position where the groove dimension falls within a desired value, and the position may be set from the empirical value.

[0031] S9 to S11: When the point _{P 9} reaches the position of the ball screw 21 is stopped, forward rotation of the ball screw 21 again. Then, when the strain gauge output becomes zero, the rotation is stopped. Thus, it is possible to set a point P ₁₀ to a desired groove size g is obtained, Figure 5
The groove dimension can be set to an appropriate value as shown in FIG.

[0032] S12～S13: amounts slide is retracted from the point P ₅ determines whether or not within the allowable range, the flow is ended to complete the positioning, if within the allowable range.
S14 to S15: If not within the allowable range, the flow returns to step S1, and the flow is executed again. If the number of executions does not fall within the allowable range even if the number of times exceeds 3, the process is terminated as NG.

In the above description, the method of setting the groove size in the case where the works 2 and 3 are firmly fitted has been described with reference to FIG. In the case of “fitting”, the present embodiment can be applied as it is.

FIG. 7 shows the relationship between the amount of movement of the ball screw and the thrust in the case of the "gap fit". In the case of this example, as shown, when the two workpieces 2 and 3 are inserted and moved to a state where the end faces are pressed against each other, the thrust q of the ball screw 21 is indicated by arrows P ₁ ′ and P ₂ . As shown, the curve rises sharply as the movement amount p of the ball screw 21 increases. In addition, ball screw 2
When thrust q of the ball screw 21 after the reverse rotation of one causes the reverse rotation further the ball screw 21 from the position becomes zero (point P ₅ position), the thrust q moved to the point P ₁₀ to hold the substantially zero value Will do. Thus, in the case of this example, FIG.
Only the amount of elastic strain is small as compared with the example shown in FIG. 4, and the positioning can be completed using the flow shown in FIG. 4 as it is.

According to the welding positioner 5 of the present embodiment, errors due to elastic deformation of the work and the apparatus itself can be corrected, so that the groove dimensions can be set with high accuracy. Also, when welding various types of workpieces, the setting of the groove size for each workpiece can be easily set by the operation program, so that there is an advantage that the equipment cost is reduced.

The method of this embodiment is particularly suitable for application to a large work or a large positioner. The reason is that the effect of elastic deformation due to thrust cannot be ignored as the size increases, and accurate setting cannot be performed unless this elastic deformation is corrected.

In this embodiment, the thrust detecting means for the moving frame using a strain gauge has been described. However, a load sensor such as a load cell may be used.
Alternatively, when the moving frame is moved by a hydraulic cylinder, the thrust may be detected by detecting the hydraulic pressure of the hydraulic cylinder. In this embodiment,
Although the means using the encoder in the motor has been described as the moving amount detection means of the moving frame, encoders and linear scales may be attached to the moving frame itself.

[Brief description of the drawings]

FIG. 1 is an overall structural view of a welding positioner according to one embodiment of the present invention.

FIG. 2A is a perspective view showing a work shape, and FIG.
(B) is sectional drawing of a butt welding part.

FIG. 3 is a partially enlarged perspective view of FIG. 1;

FIG. 4 is a flowchart showing a control mode of a welding positioner.

FIG. 5 is an explanatory diagram of a groove dimension setting procedure.

FIGS. 6A and 6B are graphs (1) showing a relationship between a movement amount of a ball screw and a thrust.

FIG. 7 is a graph (2) showing a relationship between a movement amount of a ball screw and a thrust.

8 (a) and 8 (b) are diagrams for explaining a groove dimension setting method using a conventional contact gauge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arm 2 Main body work 3 Bracket work 4 Backing material 5 Welding positioner 7 Fixed frame 8 Moving frame 12, 16, 17 Work fixing jig 13 Work support jig 19 Bracket 20 Ball screw nut 21 Ball screw 22 Servo motor 23 Strain Gauge 24 controller

Claims (4)

[Claims] 1. A first frame mounted on a fixed frame using a welding positioner having a fixed frame and a moving frame.
A method for controlling a welding positioner for setting a groove dimension of a butt weld portion between a workpiece and a second workpiece mounted on a moving frame to a predetermined value, comprising: First, the moving frame is advanced to a position where the end faces of the first work and the second work are pressed against each other, and then the moving frame is retracted until the thrust of the moving frame becomes zero. The moving frame is further retracted until the moving amount reaches the first set value,
Then, the moving frame is further retracted until the moving amount reaches a second set value, and finally the moving frame is advanced until the thrust becomes zero. 2. A first frame mounted on a fixed frame using a welding positioner having a fixed frame and a moving frame.
A welding positioner control device for setting a groove size of a butt welding portion between a workpiece and a second workpiece mounted on a movable frame to a predetermined value, wherein the movable frame is moved toward and away from the fixed frame. Moving means for moving the moving frame, a thrust detecting means for detecting a thrust of the moving frame, a moving amount detecting means for detecting a moving amount of the moving frame, and a control means for controlling movement of the moving frame by the moving means. The control means moves the moving frame in the approaching direction until the thrust detected by the thrust detecting means reaches a predetermined threshold, and then separates the moving frame until the thrust becomes zero. In the direction of movement, and thereafter the moving frame is further moved away from the moving frame until the moving amount detected by the moving amount detecting means reaches a first set value. And then move the moving frame further in the separating direction until the moving amount reaches a second set value, and finally move the moving frame in the approaching direction until the thrust becomes zero. A control device for a welding positioner, which controls the moving means. 3. The method according to claim 1, wherein the predetermined threshold is a value between the first work and the second
Value that is sufficiently larger than the maximum value of the insertion resistance of the workpiece,
The first set value is a value corresponding to a groove dimension of the butt weld, and the second set value is a predetermined value corresponding to a thrust when the movement amount reaches the first set value. The welding positioner control device according to claim 2, wherein the value is obtained by multiplying the elastic strain constant. 4. The welding positioner control device according to claim 2, wherein the moving means moves the moving frame by a ball screw driven by a motor.