JPH09314329A - Device for welding internal face of box shape block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically and effectively weld an internal face of a box shaped block by installing a turning stand at the top end of a horizontal telescopic arm and mounting an articulated welding robot on the above. SOLUTION: In the state with an opening part of a box shaped block 20 arranged in front of a fixing stand 2, a robot turning stand 4 is fallen forward and an articulated robot 10 is extended horizontally, a horizontal telescopic arm 3 is expanded, the articulated robot 10 is inserted inside the block from a narrow part of a diaphragm, etc., and it is stopped at a prescribed position. Then, the robot turning stand 4 is turned, the articulated robot 10 is actuated, a welding torch is moved to the welding start point and the automatic welding is executed. In this case, welding is executed by making the welding weaving frequency without the range of a resonance frequency ±0.5Hz of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a box-shaped block inner surface welding apparatus for welding the inside of a box-shaped block such as a bridge.

[0002]

2. Description of the Related Art Conventionally, as a method of welding the inner surface of a box-shaped block such as a box girder of a bridge, an operator enters the block, welds the lower surface of the block by downward position welding, and then turns the block itself. Then, a new bottom surface of the block is welded again by downward position welding, and this process is repeated to weld all four surfaces. This method has a problem in labor saving because the worker performs all welding, and there is also a problem in working efficiency because the turning step of the box-shaped block is included.

As a means for solving these problems, for example, Japanese Unexamined Patent Publication No. 6-143162 proposes a box type workbench device for blocks. This device is provided with a horizontal telescopic beam that is vertically movable and telescopic on a swivel base, and a workbench is provided at the tip of the beam via a rotary arm that is vertically rotatable. With this device, the welding work table can be inserted deeply even if the box-shaped block has a narrow portion, and the work table can be stably supported at any position. Using this device, a worker can ride on the work table and weld the entire inner surface of the block.
The step of turning the box-shaped block can be omitted.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The method of Japanese Patent Publication No. 162 has the following problems. Although it became possible to stably fix the workbench inside the box-shaped block, since the welding is performed by the worker, the problem of labor saving still remains. Further, the welding work in such a closed space often causes a bad environment in terms of temperature, ventilation, etc., which is also a problem from the viewpoint of safety and hygiene.

Further, this device has a structure for supporting the horizontal telescopic beam by the support legs and stably supporting the workbench, but normally, a reinforcing member such as a diaphragm, a rib or a stiffener is provided in the box-shaped block. It is attached, and there is a high possibility that when the support leg is grounded to the skin plate, it interferes with these reinforcing members and proper support cannot be performed. Measures such as expanding and contracting the support legs may be considered to avoid interference with the reinforcing member, but the structure becomes complicated, the manufacturing cost increases, and the size of the device increases, so that the horizontal expandable beam can be installed inside the box block. There is also a risk of interference with the diaphragm etc. when inserting.

The present invention solves the above problems and allows a welding robot to be inserted deeply and reliably supported even if the box-shaped block has a narrow part, and the welding can be performed automatically and efficiently. An object is to provide an inner surface welding device for a mold block.

[0007]

The box-type block inner surface welding apparatus of the present invention for solving the above-mentioned problems is provided with a horizontally extendable / contractible arm which is extendable / contractible on a fixed base, and is rotatable at the tip of this horizontally extendable / contractible arm. A robot swivel base is provided on the swivel base, and an articulated welding robot is mounted on the swivel base. In addition, the box-shaped block inner surface welding method of the present invention for solving the above-mentioned problems uses the above-mentioned device, and sets the welding wibbing frequency to the resonance frequency of the above-mentioned device ± 0.5H.
It is characterized in that welding is performed outside the range of z.

Here, the resonance frequency means the frequency f _{R at} which the amplitude becomes maximum (theoretical infinite natural vibration frequency) f _R, and outside the range of the resonance frequency ± 0.5 Hz is F ₁ <(f _R -0.5) or F _2> (refer to f _R +0.5) frequencies F ₁ or F ₂ as is.

[0009]

According to the above configuration, the horizontal telescopic arm is arranged in a state where the opening of the box-shaped block is arranged in front of the fixed base, the robot swivel base is tilted forward, and the articulated robot is extended in the horizontal direction. Extend and insert the articulated robot into the block from the narrow part such as a diaphragm and stop it at a predetermined position. Then, it is possible to perform automatic welding by rotating the robot swivel base and operating the articulated robot to move the welding torch to the welding start point. At this time, it is necessary that the articulated robot is supported without vibrating during welding. By using the apparatus and method of the present invention, the supporting leg as disclosed in the above-mentioned JP-A-6-143162 can be obtained. It is possible without using. The reason will be described below. If it is considered that the periodic force acts on the free end of the cantilever by simplifying the case of welding with the device of the present invention, the free vibration of the free end of this device is given by the following equation (1).

[0010]

[Equation 1]

Where ω: circular frequency of periodic force ν = √ (gIE / wA) P ₀ : tension amplitude acting on the free end E: Young's modulus A: beam cross-sectional area l: beam length I: beam Second moment of area w: unit volume weight of beam As is clear from these, the amplitude is 1 + cos (√ (ω / ν) l) · cosh (√ (ω / ν) l) = 0. ...... (2), the resonance phenomenon occurs and the maximum. In theory it is infinite. If this resonance phenomenon is avoided, the vibration can be suppressed to a slight amount. In the device of the present invention, the force applied to the free end is the reaction force caused by the movement of the robot, so that the frequency of the periodic force is the weaving frequency. The inventors examined the relationship between the weaving frequency and the amplitude of the device of the present invention, and as a result, when the resonance frequency was f _R , (f _R ± 0.
5) It has been found that, outside the range of Hz, good results can be obtained without generating vibration in the horizontal telescopic arm. (F _R ±
In the range of 0.5 Hz, large vibration was generated in the horizontal telescopic arm due to resonance, and welding was impossible. Of course, even if the frequency is other than (f _R ± 0.5) Hz,
A good welding condition range is limited to a narrower range from the viewpoint of arc stability and the like, so an appropriate condition may be selected from the condition range of the present invention depending on the situation.

On the contrary, the weaving frequency that enables good welding is first determined, and the (f _R of the welding device of the present invention is determined.
The welding device may be designed so that ± 0.5) Hz does not fall on its weaving frequency. (F _R ±
Even if the frequency is outside the range of 0.5) Hz, some vibration is generated, but as is clear from the above formula (1), the amplitude is the force acting on the free end and the arm disconnection. It is determined by the area and the moment of inertia of area of the arm, and if the shape of the arm is designed according to the size of the robot that determines the force acting on the free end and the weaving condition, (f _R ± 0.5) If the frequency is other than Hz, it is easy to set the amplitude within a range where there is no problem in welding of about 0.5 mm or less. For example, when a large robot is used and the reaction force of its movement becomes large, the bending area of the arm can be increased by increasing the cross-sectional area of the horizontal telescopic arm or by making it a shape with a large second moment of area. is there.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the box-shaped block inner surface welding apparatus of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the welding apparatus 1 of the present invention includes a fixed base 2 provided with a retractable horizontal arm 3 and a pivotable robot swivel base 4 provided at the end of the horizontal extendable arm 3. 4 is equipped with an articulated welding robot 10. When the welding device 1 is inserted into the box-shaped block 20, the robot swivel base 4 is tilted forward and the horizontal telescopic arm 3 and the articulated robot 10 are extended horizontally as shown in FIG. It can be inserted into the inside through the narrow part such as the narrow diaphragm 21. After the insertion, as shown in FIG. 3, the robot swivel base 4 is raised or lowered in the box-shaped block 20 to bring the robot 10 close to the welding portion and the robot 10 performs automatic welding.

4 to 6 show an example of the articulated robot 10, FIG. 4 is a side view in the same posture as FIG. 1, and FIG.
Is a front view thereof. When the robot 10 is rotated about the rotation shaft 11 in the direction of the arrow 12, the robot 10 assumes the posture shown in FIG. FIG. 6 shows a state in which the multi-joint is further extended to a stretched posture in which it is almost in a straight line, which is similar to the state shown in FIG. Further, it can be tilted in the direction indicated by arrow 13.

In these examples, the robot swivel base has only one rotating shaft in the horizontal direction and at a right angle to the expanding / contracting direction of the horizontal expanding / contracting arm, but a combination of plural rotating shafts having different rotating shaft directions is used. Alternatively, the robot may be more easily approached to the welding portion. The resonance frequency of the welding apparatus of the present invention varies depending on the shape, dimensions, material of the apparatus, arm length extended from the fixed base, etc., but the resonance frequency is 5.3 Hz, 4.0H.
Two types of devices, z, were manufactured. As the example of the present invention, the weaving frequency when welding using this device was 3
Hz and 6 Hz, and a resonance frequency of 5.3 Hz as a comparative example.
In the device of 5Hz and 5.5Hz, the resonance frequency is 4.0Hz
Welding experiments were carried out at 3.8 Hz and 4.2 Hz with the device of. Welding position is horizontal fillet welding, wibbing width is 3mm,
The welding speed was fixed at 50 cm / min. The experimental results are shown in Table 1. As shown in Table 1, in the examples of the present invention, almost no vibration was generated during the wiping, and welding was possible without any problem if the current-voltage conditions were appropriate. On the other hand, in the comparative example, a large vibration was generated in the arm during the wiping, and good results were not obtained regardless of the current / voltage conditions.

[0016]

[Table 1]

[0017]

According to the present invention, since the fixed base is provided with a retractable horizontal arm, and the articulated welding robot is mounted on the robot swivel base rotatably provided at the end of the horizontal expandable arm. By inserting the horizontal telescopic arm and the articulated robot horizontally when inserting it into the box-shaped block, it became possible to insert it into the inside through the narrow part such as the narrow diaphragm. Further, since the multi-joint type robot is mounted, the welding inside the box block, which was conventionally performed manually, can be automatically welded, which is effective in improving the working environment and saving labor. Furthermore, by setting the welding wibbing frequency outside the range of the device resonance frequency ± 0.5 Hz, it is possible to support the horizontal telescopic arm and the articulated robot at its tip without the need for devices such as support legs that were required in the past. Since it can be fixed, the cost of the device can be reduced, and since it is not necessary to consider the interference between the reinforcing member inside the box block and the supporting legs, it can be applied to a wider range of box blocks. became.

[Brief description of drawings]

FIG. 1 is a side view (reduced state) of an apparatus according to an embodiment.

FIG. 2 is a side view (extended state) of the apparatus according to the embodiment.

FIG. 3 is a side view (a state during welding) of the apparatus according to the embodiment.

FIG. 4 is a side view of the robot.

FIG. 5 is a front view of the robot.

FIG. 6 is a side view of the robot.

[Explanation of symbols]

 1 Welding device 2 Fixed base 3 Arm 4 Robot swivel base 10 (Multi-joint type) Welding robot 11 Rotation axis 12, 13 Arrows 20 Block 21 Diaphragm

Front Page Continuation (72) Inventor Tetsuya Kida 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Works Ltd. (72) Inventor Keiji Nakata 2-3-2 Uchiyuki-cho, Chiyoda-ku, Tokyo Kawasaki Steel Co., Ltd. In the company

Claims (2)

[Claims] 1. A horizontal extensible arm is provided on a fixed base, and a robot swivel base is rotatably provided at the end of the horizontal extendable arm, and an articulated welding robot is mounted on the swivel base. Box-type block inner surface welding equipment. 2. A box-type block inner surface welding method, wherein the apparatus according to claim 1 is used, and welding is performed with a welding wibbing frequency outside a range of a resonance frequency of the apparatus of ± 0.5 Hz.