JPS6254588B2 - - 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, the corners l ₁ and l ₂ of which 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 adopts a cart rotation (spin) type,
The purpose of this invention is to provide a self-propelled truck that does not float during rotation, does not use a cam plate, and 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, which are provided on both sides of the cart and one of which is rotated in reverse when the cart spins, are rotatably attached to the lower center of the cart and suspended by a spring. The electromagnet is attached to the running surface due to the force, is released when the force is de-energized, and is attached to the running surface at the intersection of the welding lines to become the central axis of the spin of the cart. A welding torch moving device for moving the welding torch forward and moving it backward 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 24 provided on the lower center surface, vertical welding material of the vehicle body (vertical plate)
It consists of a pair of guide arms 25, 25', etc., which are installed on the side and make the cart run along the vertical plate, and a welding torch 30.
is installed 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 25 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; 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 24. That is, when the crossing point B is reached, it is sensed by the roller-equipped sensor 26 and the electromagnet 24 is excited, and the electromagnet 24, which was slightly lifted above the bottom plate 10 by a spring (not shown), is attracted to the bottom plate 10 by magnetic force. Furthermore, the drive wheel 22 on the non-welded line side is switched from a straight forward electromagnetic clutch to a reversing electromagnetic clutch to rotate in the opposite direction, and the guide arms 25 and 25' are unlocked so that they can rotate freely. Therefore, the cart 20 starts spinning. When it spins 90 degrees, the cart assumes the same attitude with respect to the vertical plate 11 as it did with the vertical plate 12, and at this time the guide arm 2
5 and 25' are restored, the electromagnet 24 is deenergized, and the non-welding line side, that is, the outer drive wheel 22, is switched from the spin (reverse) electromagnetic clutch to the straight-ahead electromagnetic clutch to restore forward rotation. It progresses along the vertical board 11. The dotted line 20B is thus the vertical plate 11
The cart 20 is shown starting to move along.

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 25, 25' are rotatable, an electromagnet for spinning is provided, and an electromagnetic clutch drives the drive wheel on the non-welding line side in reverse rotation when spinning. The only difference is in the degree to which they are equipped.
Next, details of each part will be explained using a specific example.

3 to 5 show specific examples of the body 21 portion of the truck 20. FIG. The electromagnet 24 has a shaft 24a, and a bearing 31 connects the central part of the vehicle body, specifically the driving wheels 22, 22.
The electromagnet is rotatably pivoted to the center of the vehicle body on a line connecting the rotation centers of the electromagnet, 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 24, and this gear 33 meshes with a gear 35 of a potentiometer 34. potentiometer 3
The outer casing of No. 4 is attached to the vehicle body 21 by a support 36, and the gear 35 is fixed to the rotating shaft.
A return spring 37 is attached to 5. The trolley
When spinning 90 degrees, the electromagnet 24 is attracted to the running surface and fixed, and the vehicle body and the rotor of the potentiometer 34 rotate. After the rotor has spun 90 degrees, it returns to its original state so that it is always in the same state, and the spring 37 performs this return. The potentiometer outputs the cart spin angle θ, which is used to stop the 90° spin and is also 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 in the example shown in FIG. 4, when traveling straight, the inner drive wheel 51 is rotated in the normal direction by the first gear train 52 driven by the motor 50, and the outer drive wheel 54 is also rotated. Normal rotation is performed by the second gear train 55 via the electromagnetic clutch 53 for normal rotation. During this straight-ahead running, the reversing electromagnetic clutch 59 is directly connected to the third gear train 56.
are separated. On the other hand, when the cart 21 spins, the electromagnet 24 is attracted to the running surface, and at the same time, the forward rotation electromagnetic clutch 53 is released and the reverse rotation electromagnetic clutch 5 is released.
9 are connected, and the rotation of the drive motor 50 is caused by the gears 83, 84 of the first gear group 52, the third gear group 56,
and 85, the second gear group 55 is reversed to reverse the outer drive wheel 22, and the trolley 21 is rotated about the shaft 24a.

FIG. 5 shows another example, in which when the truck 21 runs straight, the motors 50 and 90 operate the motors 81 and 82, the electromagnetic clutch 53 and the gear 86, and the gears 91 and 92, the electromagnetic clutch 94 and the gear 93. The gears 51 are rotated synchronously, and the pair of driving wheels 22 are also rotated forward in synchronization in the same direction. On the other hand, the spinning of the truck 21 causes the electromagnet 24 to be attracted to the running surface, and at the same time, the outer drive wheel 22 is also reversed by the reverse rotation of the motor 50, and the truck 21 is rotated around the shaft 24a.
Do this by rotating 1. In this way, by spinning the cart 21 by rotating the inner drive wheel 22 in the forward direction and rotating the outer drive wheel 22 in the reverse direction, an extremely smooth operation can be obtained without any resistance. .

A gear 58 of a pulse generator 57 is also connected to the gear 51 of the inner drive wheel 22 shown in FIG. 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. Fifth
In the figure, the same thing can be done by using motors 50, 90 connected to pulse generators PG and controlling them using the pulse signals. 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 mentioned above can be used to control welding stop while the part is running. .

FIG. 6 shows the rotation and locking mechanism of the guide arms 25, 25'. The guide arm is rotatably supported by the vehicle body 21 by 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. When the solenoid 65 is energized and 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 6 when spinning the trolley
5, the electromagnet 24 is energized, or the spin axis is established, and the electromagnetic clutch 53,
The decoupling of the spindle 59 and the like are performed based on 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. 6, a scallop detector 67 is attached to the front guide arm 25. 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 point at which welding should be stopped and the point 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 detector 6
7 and in FIG.
This control is performed by the output pulse No. 7.

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 trolley 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), the spin angle θ is measured with the potentiometer 34 in FIG.
4, it is sufficient to move the torch forward and 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. 9, then in the range of θ = 0 to π/4, v/L = N. /l,S cosθ=N,l
Since there is a relationship of cosθ=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. 10 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, and 7
3 and 74 are digital-to-analog converters, 75 is a torch aim position setter, 76 is a truck speed detector, and 7
7 and 78 are adders and subtracters. multiplexer 71
Then, the spin angle θ output by the potentiometer 34 and the torch aim position set value D from the setting device 75 are taken in via the analog-to-digital converter 72, and the speed reference value Vs for the traveling motor 50 is calculated by performing the above calculation. Outputs the torch advance/retreat amount setting value Ls. These are converted into analog quantities by D/A converters 73 and 74, and then compared with the actual truck speed v and torch forward/backward movement amount P by adders and subtracters 77, 78, and feedback control is performed to make v and P as set values. will be carried out. FIG. 11 shows a flowchart of torch aiming position control, and FIG. 12 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. 13 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 cart of the present invention in a welding work state, and Figs. 3, 4, and 5 are examples of the present invention. 6 is an explanatory diagram of the copying guide arm section, FIG. 7 is an explanatory diagram of the welding torch section, and FIGS. 8 and 9 are diagrams of the welding torch during spinning. An explanatory diagram of changes in torch aiming position and welding speed, Figure 10 is a block diagram explaining the main part of control by the microprocessor, Figures 11 and 12 are flowcharts, and Figure 13 is a diagram of the vertical plate detector. FIG. 14, which is an explanatory diagram of the detection error, is a flowchart showing how to correct it. In the drawing, 20 is a self-propelled welding cart, 25, 25' are guide arms, 53, 59, 94 are electromagnetic clutches, 22
is a driving wheel, 24 is an electromagnet, l ₁ and l ₂ are welding lines, 40
8 is a welding torch moving device, and 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, which are provided on both sides of the trolley and one of which is driven in reverse when the trolley spins, are rotatably attached to the lower center of the trolley and suspended by a spring, and are biased against the running surface. The electromagnet is attached to the trolley and is released from the attraction by deenergization, and is attracted to the running surface at the intersection of the welding line to become the central axis of the trolley spin. A trackless self-propelled welding trolley for welding, comprising: a welding torch moving device for moving the welding torch backward from the welding torch.