JPS6327118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extinguishing a gas flame at the end of a welding operation in automatic gas welding.

Gas pressure welding does not require a power source and produces joints with high joint strength, so it is widely used for on-site work on reinforcing bars and rails. There is also a method of dividing the pressure welding process into a plurality of steps and sequentially executing these steps through sequence control to perform the work in a practical manner.

FIG. 1 shows an example of an automatic gas pressure welding device, in which a main body 6 of the pressure welding device 5 is supported by a workpiece 1 via a fixing chuck 7. As shown in FIG. A ring-shaped burner 8 and a sliding block 10 are attached to the main body 6, which eject gas flames from a plurality of nozzles 9 to heat the joint 3. A moving chuck 11 provided on the sliding block 10 grips the other workpiece 2. The sliding block 10 is moved along the axis of the materials 1 and 2 to be joined by the action of a hydraulic cylinder 12 connected thereto, and the joint 3 is moved by the burner 8.
The heated materials 1 and 2 are pressed together and joined together. The operation of the device is controlled by a controller (not shown) including a microcomputer.

In the automatic gas pressure welding described above, gas flames have conventionally been extinguished as follows. When the joining portion 3 is heated to a required pressure welding temperature, the materials 1 and 2 to be joined begin to be set up. When the upset has reached the set value and is completed, the burner 8 is evacuated from the joining position and the supply of oxygen to the burner 8 is stopped at the same time.

The conventional fire extinguishing method described above had the following problems.

(a) When the supply of oxygen is stopped, the gas flame formed in the burner 8 becomes a flame of only combustible gas (hereinafter described as acetylene gas). This gas flame carburizes the joint and accelerates melting of the joint, making it susceptible to blowholes and drips.

(b) Due to a delay in the operation of the equipment's mechanical system, burner 8
The burner 8 is still in the position of the joint 3 when the oxygen supply is stopped because the burner 8 is not evacuated in time. At this time, the gas flow rate from the burner is slowed down due to the stoppage of oxygen, and flashback is likely to occur due to sparks from the joint.

This invention was made in automatic gas pressure welding in order to solve the above-mentioned problems with conventional fire extinguishing methods.It is a simple method that can obtain good joints with no defects, and also prevents backfire. The purpose is to provide a gas flame extinguishing method that does not cause gas flame extinguishing.

In the gas flame extinguishing method of the present invention, evacuation of the burner from the joining position is started before the upset is completed. After the upset is completed, the supply of oxygen to the burner is stopped, the flow rate of acetylene gas is reduced, and the fire is extinguished.

In this invention, as described above, the burner starts to be evacuated before the setup ends, and then the supply of oxygen is stopped and the flow rate of acetylene is reduced, so even if the gas flame becomes an acetylene-only gas flame, this can be avoided. Since the joints are never touched,
There are no blowholes or drips at the joints as described above. Additionally, since the burner is far away from the joint at the time of extinguishing the fire, even if sparks are generated from the joint, they will not reach the burner and the flow rate of acetylene gas will be small, so backfire will not occur when the fire is extinguished. rare. Furthermore, since the present invention only requires early evacuation of the burner and throttling of the acetylene gas, it can be carried out very easily without requiring any special equipment.

This invention will be explained in detail below.

FIG. 2 shows an example of a gas pressure welding process including the fire extinguishing method of the present invention, and the process consists of 10 steps. A, B, and C are periods during which oxygen and acetylene gas are ejected from the burner 8 (see FIG. 1). In D and E, the burner 8 is the material to be welded 1,
F indicates the period during which the burner 8 vibrates or moves in the axial direction of the burner 8, and F indicates the period during which the burner 8 swings around the axis. Further, G is a period during which the hydraulic pump operates to supply pressure oil to the hydraulic cylinder 12, and H is a period during which pressure oil is released from the hydraulic cylinder 12 and the pressure on the joint portion 3 is released. Further, I indicates the pressurizing pattern of the joint 3 due to the operation of the hydraulic cylinder 12, and J indicates the amount of compression, that is, the amount of upset, of the joint 3 due to the pressurization.

When the welding part 3 is heated to the required pressure welding temperature in the pressure welding step (step 6), the hydraulic pump is driven to start assembling the materials 1 and 2 to be welded. Then, the offset amount is the set value M
When the temperature reaches 1/2 to 2/3 (point a in FIG. 2), the burner 8 is retracted from the joint 3. The amount of offset is the amount of compression of the joint 3, for example, by the sensor 1 that detects the displacement of the sliding block 10 shown in FIG.
Measured by 3. Further, the burner 8 is retracted by automatically moving the burner 8 to the position shown by the dotted line in response to a signal from the sensor 13.

Point b when there was a slight delay in the start of evacuation of the burner 8 mentioned above.
The supply of oxygen to burner 8 is stopped and the flow rate of acetylene gas is reduced. The flow rate of the acetylene gas at this time is suitably about 1/3 to 4/5 of the flow rate in the steady heating state (steps 3 to 7) in order to prevent flashback during extinguishing.

The gas flame is extinguished while the burner 8 is evacuated as described above, the supply of oxygen is stopped, and the flow rate of acetylene gas is throttled (time point C).

FIG. 2 shows an example of an automatic gas pressure welding process, and it goes without saying that the fire extinguishing method of the present invention can be applied to gas pressure welding processes other than those described above.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a gas pressure welding apparatus, and FIG. 2 is a process diagram of gas pressure welding including the steps of the fire extinguishing method of the present invention. DESCRIPTION OF SYMBOLS 1, 2... Material to be joined, 3... Joint part, 5... Pressure welding device, 6... Main body, 7... Fixed chuck, 8... Burner, 9... Nozzle, 10... Sliding block, 11... Moving chuck, 12... Hydraulic cylinder , 13... Upset amount sensor.

Claims (1)

[Claims] 1 Before the setup is finished, the burner starts to retreat from the joining position, and after the setup is finished, the supply of oxygen to the burner is stopped and the flow rate of combustible gas is lower than the flow rate in the steady heating state, and then A fire extinguishing method in automatic gas pressure welding characterized by extinguishing a fire.