JPS6254587B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a trackless self-propelled truck suitable for horizontal fillet welding of box-shaped structures.

When welding ship hulls, we often have to weld the corners of steel plates assembled into a box shape. FIG. 1 is a diagram showing an example of this, in which 10 is a horizontal member that becomes the bottom of the ship, and 11 and 12 are vertical members that are reinforcing materials.
The vertical members 11 and 12 extending vertically and horizontally and the horizontal bottom plate member 10 constitute a rectangular parallelepiped box-shaped structure, whose corners l ₁ and l ₂ are welded.

Corner between horizontal member 10 and vertical members 11 and 12
l ₁ and l ₂ are rectangular, and several methods have been considered for automatically horizontal fillet welding using a welding torch mounted on a self-propelled trolley. In one method, the cart runs along the sides of the rectangle, rotates 90 degrees at the corners of the rectangle, and welds the corners with a torch that protrudes to the side of the cart. The other method is to run the cart along the sides of the rectangle, but at the corners, it does not turn 90 degrees but instead moves sideways, so that the cart can move forward, right, backward, etc. while going around the rectangle once. The torch is mounted on a trolley and rotates 90 degrees at each corner, automatically performing fillet welding. However, the latter type has problems such as a complicated structure and poor stability, as guide arms for copying travel extend out on all sides, casters are used for the traveling wheels, and a torch rotation mechanism is required. In the former case, since the trolley rotates 90 degrees at the corner, there is no need to rotate the torch, and therefore the torch can be fixed to the trolley with a mechanism that only moves forward and backward but does not rotate, making it more compact and stable. However, the 90° rotation mechanism of the cart is a problem.

In conventional equipment, in order to rotate the cart 90 degrees, for example, the stand is lowered to levitate the cart, and the cart is rotated in this state.
If the cart floats up, the torch also floats, causing a problem of welding position shift. It would be possible to keep the torch height unchanged even when the cart floats up, but this would inevitably complicate the mechanism. In addition, in the method of rotating the cart, there is a problem in how to handle the guide arm for tracing travel. Regarding this point, some models use a cam plate, but this requires a large cam plate, making it inevitable to increase the size of the truck.

Although the present invention uses a rotating trolley type, there is no floating of the trolley during rotation, and no cam plate is used.
Therefore, the present invention aims to provide a self-propelled trolley that can be made smaller and simpler. The trackless self-propelled welding cart of the present invention is provided on the welding line side of the cart, and has a pair of locked positions during tracing traveling and an unlocked position rotated backwards against the spring. A pair of drive wheels are provided on both sides of the truck, one of which is connected to and separated from the motor by an electromagnetic clutch, and the drive wheel is rotatably mounted on the lower center of the truck and suspended by a spring. , an electromagnet that is attached to the running surface by energization, released by attraction by deenergization, and is attached to the running surface at the intersection of the welding line to become the central axis of the cart spin. The welding torch is characterized in that it includes a welding torch moving device that moves the welding torch forward and back.This will be described in detail below with reference to embodiments.

FIG. 2 is a diagram illustrating an outline of the self-propelled welding cart of the present invention. This welding self-propelled trolley 20 has a car body 2
1. Drive wheels 22 provided on the left and right sides, casters 23 provided on the front and rear, spin electromagnet 27 provided on the lower center surface, vertical welding material of the vehicle body (vertical plate)
It consists of a pair of guide arms 24, 25, etc., which are provided on the side and allow the cart to travel along the vertical plate, and a welding torch 30 is mounted to perform fillet welding. Bottom plate 10 and vertical plate 1
The corners with 1 and 12, that is, the weld lines l ₁ and l ₂ are the vertical plates 11
and 12 are orthogonal to each other at the intersection B, and accordingly, as shown by the chain line L, the running trajectory of the truck 20 is also orthogonal at the intersection B at the vertical plate 12 side A and that of the vertical plate 11 side C. . That is, as is known, if the front guide arm 24 is made shorter than the rear guide arm 25, the traveling direction of the truck 20 will be the direction in which it approaches the vertical plate 12, but this is because the guide arm 24 projects against the vertical plate 12. The truck 20 is blocked by the collision and eventually moves along the vertical plate.

When reaching the intersection B, the cart 20 rotates. A dotted line 20A indicates a state in which the cart has rotated (spun) by about 45 degrees. This spinning is performed using an electromagnet 27. That is, when the intersection B is reached, it is sensed by the roller-equipped sensor 26 and the electromagnet 27 is excited, and the electromagnet 27, which was slightly lifted above the bottom plate 10 by a spring (not shown), is attracted to the bottom plate 10 by magnetic force. Further, the drive wheel 22 on the non-welding line side is disconnected from the motor by the electromagnetic clutch, so that only the drive wheel 22 on the welding line side rotates.
Since the wheels 4 and 25 are unlocked and can rotate freely, the cart 20 begins to spin.
When it spins 90 degrees, the cart assumes the same attitude with respect to the vertical plate 11 as it did with respect to the vertical plate 12, and at this time, the lock of the guide arms 24 and 25 is restored, and the electromagnet 2
7 is deenergized, the electromagnetic clutch resumes the rotation of the drive wheel and motor on the side opposite to the vertical plate, and the vehicle moves along the vertical plate 11. A dotted line 20B indicates the truck 20 which has thus started moving along the vertical plate 11.

As is clear from the drawings, this welding cart has a simple structure. That is, compared to the conventional straight-travel welding cart, the guide arms 24 and 25 are rotatable, an electromagnet for spinning is provided, and an electromagnetic clutch is provided to free the drive wheel on the non-welding line side during spinning. They only differ in degree. Next, details of each part will be explained using a specific example.

3 and 4 show a specific example of the body 21 portion of the truck 20. FIG. The electromagnet 27 has a shaft 27a, and a bearing 31 connects the central part of the vehicle body, specifically the driving wheels 22, 2.
The electromagnet is rotatably attached to the center of the vehicle body on a line connecting the rotation centers of the electromagnets 1 and 2, and is lifted up by a spring 32 so that the end face of the electromagnet is separated from the bottom plate 10, that is, the running surface, with a gap g when the electromagnet is running. A gear 33 is fixed to the electromagnet 27, and this gear 33 is connected to the encoder 3.
It meshes with gear 35 of No. 4. The outer casing of the encoder 34 is attached to the vehicle body 21 by a support 36, and the gear 35 is fixed to the rotating shaft, and a return spring 37 is attached to the gear 35. When the truck spins 90 degrees, the electromagnet 27 is attracted to the running surface and fixed, and the vehicle body and the rotor of the encoder 34 rotate. These are returned to their original state after a 90° spin so that they are always in the same state, and the spring 37 performs this return. The encoder outputs the truck spin angle θ, which is used to stop the 90° spin and is used as described below.

Welding torch 30 is attached to vehicle body 21 via welding torch moving device 40 . This welding torch moving device 40 includes a welding torch holder 41, its guide rod 42, a feed screw 43, and its drive motor 4.
4. Consists of a potentiometer 45 for detecting the amount of forward and backward movement of the torch. A gear 51 is connected to the drive wheel 22, and as shown in FIG.
It is driven by a motor 50 via. This gear train includes an electromagnetic clutch 53, and by energizing and deenergizing this clutch, the drive wheel 22 on the non-welded line side is connected or disconnected from the motor 50. The bogie of this example includes electromagnets 55 and 56 on the weld line side of the car body. This electromagnet faces the running surface with a gap in between, and is excited when the bogie spins to generate an attractive force, which presses the vehicle body against the running surface and increases the apparent weight of the vehicle. The cart is spun by attaching the electromagnet 27 to the running surface, freeing the driving wheel 22 on the non-welding line side by the electromagnetic clutch 53, and rotating only the driving wheel 22 on the welding line side by the motor 50. Although it is conceivable that slipping may occur due to driving, this slipping can be avoided by increasing the apparent weight of the vehicle by generating attractive force in the electromagnets 55 and 56.

A gear 58 of a pulse generator 57 is also connected to the gear 51 of the drive wheel 22 . The output pulses of the pulse generator 57 indicate the speed of the truck, the distance traveled, etc., and can be used for controlling these. In particular, the box-shaped structure of the ship's hull is provided with a scallop S for draining, as shown in Figure 1, and although welding is not performed in this part, the output pulse of the pulse generator 57 is used to control welding stop while the part is running. It can be used for etc.

FIG. 5 shows the rotation and locking mechanism of the guide arms 24, 25. The guide arm is rotatably supported by the vehicle body 21 via a shaft 61. A spring 62 is provided between the shaft 61 and the guide arm, which allows for return. Further, a recess 63 is provided at the end of the guide arms 24 and 25 beyond the shaft 61, and the tip of a locking piece 64 driven by a solenoid 65 fits into the recess 63 when the truck travels in a straight line. Lock the arm in the position shown in solid line in Figure 2. energizes the solenoid 65,
When the locking piece 64 is retracted against the spring 66 so that its tip is removed from the recess 63, the guide arm becomes free and rotates freely around the shaft 61. However, since there is a spring 62, when it enters the weld line intersection and rotates backward as shown by the dotted line in Figure 2, a force that tries to return always acts, and when the solenoid 65 is deenergized in this way, the trolley When the guide arm comes out to the side of the vertical plate 11 and enters the straight-line traveling state, the locking piece 64 is pushed by the spring 66 and enters the recess 63 to lock the guide arm again. Solenoid 65 during cart spin
The energization or unlocking of the electromagnet 27, the establishment of the spin axis, and the release of the electromagnetic clutch 53 are performed by the output of the sensor 26 that detects the spin position. The sensor 26 may simply be a limit switch, and produces the above output by coming into contact with the vertical plate 11. In the example shown in FIG. 5, a scallop detector 67 is attached to the front guide arm 24. This detects the vertical plates 11 and 12, and when the vertical plates run out at the scallop, an output indicating this is produced, which causes welding to be stopped for a predetermined period of time. The time at which welding should be stopped and the time at which welding should be restarted are determined by the distance between the detector 67 and the torch 30, the traveling speed, and the scallop length, so the output of the detector 67 and the output pulse of the pulse generator 57 in FIG. This control is performed by

The welding torch 30 must always aim at the welding line, and the vertical plate detector 68 attached to the welding torch holder 41 is effective for this purpose. That is, if the motor 44 is driven so that the detector 68 always maintains a predetermined gap with the vertical plate, in other words, the output of the detector 68 always becomes a predetermined value, the torch 3
0 can be made to always aim at the weld line.

When welding a welding line intersection while the cart is spinning, it is necessary to adjust the torch position by a length of l-γ=Δl, as shown in FIG. 0 here
is the spin center, l is the distance from the torch tip (arc point) to the spin center 0, and γ is the distance between the torch tip and the spin center 0 when the torch is not moved. The torch moving device 40 corrects this Δl at the weld line intersection. This correction can be performed using the vertical plate detector 68 as described above, but it can also be corrected by calculating from the spin angle. If the spin angle is θ, then Δl is Δl=γ(1/cosθ−1) in the range of θ=0 to π/4, and Δl=γ(1/sinθ−1) in the range of θ=π/4 to π/2. 1), it is sufficient to measure the spin angle θ using the encoder 34 shown in FIG. 3 and to cause the motor 44 to move the torch forward or backward by the above-mentioned amount Δl. The potentiometer 45 outputs the amount of feedback when performing this negative feedback control.

If the torch is moved back and forth by Δl at the intersection of the welding lines, the speed of the torch tip and therefore the welding speed will change even if spinning is performed at a constant speed. Since fluctuations in the welding speed are undesirable, it is better to control the spin speed so that the welding speed remains constant (there is no change compared to the welding speed in a straight section). This is also the spin angle θ
It is possible using That is, if the speed of the drive wheel on the welding line side is v, the rotational speed of the torch tip is N, and the welding speed is S, as shown in Fig. 8, then in the range of θ = 0 to π/4, v/L = N. /l, Scosθ=N, lcosθ=
Since there is a relationship of γ, v=SL/γcos ² θ, and in the range of θ=π/4 to π/2, v=SL/γsin ² θ. Since S is constant and γ and L are also constant, v
It can be changed depending on cos ² θ or sin ² θ. Such control can be easily performed using a microprocessor.

FIG. 9 shows an embodiment thereof, in which 70 is a bus connected to a microprocessor (not shown), 71 is a multiplexer, 72 is an analog-to-digital converter, 73,
74 is a digital-to-analog converter, 75 is a torch aim position setter, 76 is a truck speed detector, 77, 7
8 is an adder/subtracter. The spin angle θ output by the encoder 34 and the torch aim position set value D from the setting device 75 are taken in via the multiplexer 71 and the analog-to-digital converter 72, and the speed reference value for the traveling motor 50 is determined by performing the above calculation.
Outputs Vs and torch advance/retreat amount set value Ls. These are converted into analog quantities by D/A converters 73 and 74, and then added and subtracted by adders and subtracters 77 and 78 to obtain the actual bogie speed v.
and the torch forward/backward movement amount P, and feedback control is performed to bring v and P to the set values. FIG. 10 shows a flowchart of torch aiming position control, and FIG. 11 shows a flowchart of truck speed control to maintain a constant welding speed.

When the torch position is detected by a vertical plate detector, an error occurs according to the angle α of the supporting arm. FIG. 12 is a diagram explaining this. If the detector 68 is a contact type, an error ε will occur depending on the angle α depending on the diameter of the roller, and if the detector 68 is a non-contact type, an error ε will occur if there is an angle α. arise. The procedure for correcting this is shown in the flowchart of FIG.

As explained above, the welding cart of the present invention has a very simple configuration, but is capable of automatically continuous fillet welding of orthogonal weld lines, weld lines that form a rectangular loop, etc. It is also possible to perform control such as keeping the target position unchanged and welding speed unchanged, which is extremely effective.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a box-shaped structure, FIG. 2 is a diagram illustrating an outline of the self-propelled trolley of the present invention in a welding work state, and FIGS. 3 and 4 are diagrams illustrating an embodiment of the present invention. A schematic side view and bottom view with the section in section,
FIG. 5 is an explanatory diagram of the copying guide arm section, FIG. 6 is an explanatory diagram of the welding torch section, FIGS. 7 and 8 are explanatory diagrams of changes in torch aiming position and welding speed during spinning,
Fig. 9 is a block diagram explaining the main part of the control by the microprocessor, Figs. 10 and 11 are flowcharts, Fig. 12 is an illustration of the detection error of the vertical plate detector, and Fig. 13 shows it. This is a flowchart showing the procedure for correction. In the drawing, 20 is a self-propelled welding cart, 24 and 25 are guide arms, 26 is a sensor with a roller, 53 is an electromagnetic clutch, 22 is a drive wheel, 27 is an electromagnet, l ₁ and l ₂ are welding lines, and 40 is a welding torch. The mobile device 80 is a control circuit.

Claims (1)

[Scope of Claims] 1. A pair of guides for copying, which are provided on the welding line side of the bogie and take a locked position during copying and a position in which the guide is unlocked and rotated backwards against a spring. A pair of drive wheels are provided on both sides of the truck, one of which is connected to and separated from the motor by an electromagnetic clutch, and the drive wheels are rotatably attached to the lower center of the truck and suspended by a spring, and are driven by force. An electromagnet that is attached to a surface, released from adsorption by deenergization, and then adsorbed to the running surface at the intersection of the welding line to become the center axis of the cart spin; A self-propelled trackless welding cart for welding, further comprising a welding torch moving device for moving the welding torch backward.