JPH0710851Y2 - Hydraulic supply circuit for butt welder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic circuit of a butt welder such as a flash welder or a butt welder, and more specifically, a fixed side clamp and a movable side clamp for a member to be welded. Butt hold by, welding current is passed to the butt held end,
In a butt welding machine that applies upset force and press-contacts when both ends reach the welding temperature by the Joule heat, it is connected to three hydraulic supply circuits of the clamp system, the movable clamp servo system, and the upset system, respectively. This hydraulic circuit is configured so that the hydraulic pump can be linked by a single electric motor to set the clamp pressure, servo pressure, and upset pressure separately for each circuit.

(Prior art) Flash welding involves a flash process in which the members to be welded are repeatedly brought into contact with each other and separated from each other to generate flash and gradually increase the temperature of the joint end face by Joule heat due to a contact short-circuit, and the butt end has a welding temperature. When it reaches, it is separated from the upset process of applying forging pressure to this. In the flash process, it is important to raise the temperature of the end surface of the work piece uniformly and efficiently, but since it is the final process in the upset process,
Upset current, upset speed, upset cost, etc. are important factors.

When welding a flash welding machine with a small cross-sectional area, an air-driven one is used, but with a large cross-section, the welding machine becomes large and a high pressure is required, which requires hydraulic driving.

Generally, for flash welding of steel sheets, an upset speed of 20 to 100 mm / sec is required. If the upset speed is slow with respect to the upset current, it will explode. If it is too fast, the current density will decrease, causing poor welding. Therefore, it is necessary to select an appropriate upset speed, but this speed changes depending on the oil flow rate and oil pressure. No matter how much the hydraulic pump discharges, if there is no pressure, the upset speed will not increase depending on the temperature rise of the workpiece. Therefore, adjusting the upset pressure to control the upset speed becomes an important factor for the welder.

Therefore, the following hydraulic pressure circuits have been generally used.

In the hydraulic circuit of FIG. 1, check valves 3 and 4 and direction switching valves 5 and 6 are connected to the clamp pressure supply circuits of the clamp cylinders 1 and 2 of the fixed side clamp and the movable side clamp, respectively.
A primary pressure hydraulic pump 8 is connected to a primary side of the direction switching valves 5 and 6 via a pressure reducing valve 7. On the other hand, in the servo pressure supply circuit of the drive cylinder 9 for advancing the movable side clamp at the time of welding, the servo valve 10 for generating the servo pressure at the time of welding and the pressure reducing valve 11 at the primary side thereof are connected, and at the time of upset, A direction switching valve 12 and a pressure reducing valve 13 are connected to an upset pressure supply circuit that generates upset pressure, and the primary sides of the pressure reducing valves 7, 11, 13 are connected to a common hydraulic circuit via a relief valve 14 to form one electric motor. It is connected to an original hydraulic pump 8 driven by 15.

Next, the hydraulic circuit of FIG. 2 is a hydraulic supply circuit for upset that is generally on the market, and in this case, the feedback of the pressure reducing valve 13 is taken from the secondary side of the direction switching valve 12. Is.

The hydraulic circuit shown in FIG. 3 has an accumulation letter 17 connected between the direction switching valve 12 and the pressure reducing valve 13 in the upset pressure supply circuit.

(Problems to be Solved by the Invention) However, in the conventional hydraulic circuit shown in FIG. 1, when the upset is performed, the upset speed becomes slow due to the characteristic of the pressure reducing valve 13, and the predetermined speed cannot be controlled.
That is, the secondary pressure of the pressure reducing valve has a set value because the direction switching valve 12 is closed, and the inside of the pressure reducing valve is in a closed state after the pressure setting is completed. Direction switching valve in this state
Even if 12 is switched, it takes time for the inside of the pressure reducing valve to open. Therefore, the predetermined upset speed cannot be obtained, and the welding quality is not stable.

Next, in the case of FIG. 2, the flush pressure is set lower than the upset pressure, so that the pressure reducing valve 13 is normally fully opened. Therefore, it is considered that the source pressure is almost applied between the pressure reducing valve and the direction switching valve. If the direction switching valve is switched here, the source pressure is momentarily applied to the cylinder, and the upset speed becomes maximum.

In this way, the feedback of the upset pressure reducing valve is not pulled from the secondary side of the pressure reducing valve and is taken from the secondary side of the direction switching valve, so the pressure of the upset is not the pressure set by the pressure reducing valve and the original pressure is applied. The purpose of the pressure reducing valve has not been fully fulfilled, such as the fact that it will end up. Since the upset process is completed in a short time of about 0.1 seconds, the fact that this pressure cannot be set makes it very difficult to obtain welding conditions.

Next, in the case of Fig. 3, the upset pressure is determined by the gas set pressure in the accumulation letter, and even if the set pressure is changed by the pressure reducing valve 13, the upset pressure cannot be changed, and the original meaning of the pressure reducing valve is It's gone. Therefore, a predetermined upset speed cannot be obtained again, and there remains a problem to be solved in order to obtain stable welding quality.

Therefore, by controlling the upset speed as described above, the upset current can be increased or decreased, so that not only the welding quality can be improved but also the energy saving effect can be obtained, and the upset pressure can be set without any problem. What you do is very significant today.

(Means for Solving the Problem) The present invention has been made in view of the trends described above, in which the members to be welded are held in abutting relation by the fixed side clamp and the movable side clamp, and a welding current is applied to the ends held by the butting. In a butt welder that energizes and press-contacts by applying upset force when both ends reach the welding temperature due to its Joule heat, in the primary side of the clamp cylinder of the fixed side clamp and the movable side clamp, check valve and direction A clamp pressure supply circuit connected to the hydraulic pump via a switching valve, and a servo pressure supply circuit connected to the hydraulic pump via a servo valve on the primary side of the drive cylinder that advances the movable clamp during welding. , An upset pressure supply circuit connected to the hydraulic pump via a switching valve between the drive cylinder and the servo valve, The hydraulic pump provided on the road is linked by one electric motor, and the pressure of the two circuits of the servo pressure supply circuit and the upset pressure supply circuit can be controlled separately by the relief valve provided on the secondary side of the hydraulic pump. I did it.

(Operation) In the present invention, the hydraulic pressure pumps connected to the clamp pressure supply circuit, the servo pressure supply circuit, and the upset pressure supply circuit are linked by a single electric motor, and the servo pressure and the upset pressure are connected to the relief valve. Since it is possible to set independently from the original pressure via the setting, the upset force setting, which was difficult in the past, can be set up according to the welding conditions regardless of the shape of the work piece, the cross-sectional area, etc. It is possible to improve the welding quality.

(Embodiment) An embodiment of the present invention will be described with reference to FIG.

In the figure, the same components as those of the conventional hydraulic circuit are designated by the same reference numerals.

The clamp cylinder 1 on the fixed side and the clamp cylinder 2 on the moving side clamp and hold two objects to be welded in abutment with each other. The check valves 3 and 4 and the direction switching valves 5 and 6 are connected to the hydraulic pressure supply circuits of the clamp cylinders 1 and 2, respectively, and by opening and closing the direction switching valves 5 and 6 in response to a command signal from the welding control device. The pressure oil supplied from the hydraulic pump 8 connected to the hydraulic circuit is supplied to the piston working chamber A or the piston return chamber B of each cylinder 1 and 2 to clamp and release the workpiece.

In the case of the figure, the relief valve 18 is not necessarily provided in the clamp pressure supply circuit, but when the pressure oil to the clamp cylinder reaches the set value, the relief valve provided on the secondary side of the hydraulic pump 8 is provided. The valve 18 works to maintain a constant pressure. Therefore, when a load acts on the primary side of the directional control valve, excess oil is returned to the oil tank 19.

The drive cylinder 9 that moves the moving side clamp during welding is
A servo pressure supply circuit in which a direction switching valve 13 and a servo valve 10 are connected to a hydraulic circuit connected to the piston working chamber C and the piston return chamber D, and a relief valve 20 is connected to the primary side of the servo valve 10 , Hydraulic pumps 22 and 23 are respectively connected to an upset pressure supply circuit in which a relief valve 21 is connected to the primary side of the directional control valve, and these three hydraulic pumps 8, 22 and 23 are connected to one motor 24. The structure is linked.

The operation of the present invention will be described with the above configuration. After the two members to be welded are set at the positions where the clamp cylinders are opened, a command signal is sent from the welding program control device to the directional control valves 5, 6 for clamping. The direction switching valves 5 and 6 are switched by their electric signals to supply pressure oil to the piston working chambers A of the clamp cylinders 1 and 2, and the work to be welded is fixed and movable by pressing the cylinder rod. Hold firmly on.

Next, a welding start signal is sent from the welding program control device to the servo valve, the servo valve 10 is opened by the input signal, the piston working chamber C of the drive cylinder 9 is filled with pressure oil, the moving side clamp is advanced, and the flash is performed. Enter the welding process.

The moving side clamp 2 gradually moves to the fixed side clamp while flashing the work to be welded by the movement of the servo mechanism, and it is detected from the moving amount of the moving side clamp that the butt end temperature rises to the welding temperature. Alternatively, the direction switching valve 13 of the upset pressure supply circuit is opened by a signal from a timer or the like to supply pressure oil to the piston working chamber C of the drive cylinder 9, and immediately enter the upset process, and the upset force set in the relief valve 21 is applied to the butt end. The part is shrunk and welding is completed.

Hereinafter, since the clamp cylinders 1 and 2 and the drive cylinder 9 are prepared for the next operation, the operation of each hydraulic system is returned.

(Effects of the Invention) As described above, according to the present invention, the clamp pressure supply circuit, the servo pressure supply circuit, and the upset pressure supply circuit of the butt welding machine are provided with independent hydraulic pumps by one electric motor. Since it is possible to set each pressure independently from the original pressure via the relief valve in at least the hydraulic circuit of at least the servo system and the upset system by interlocking, the upset force that could not be set independently as in the past, Regardless of the shape of the work piece or the size of the cross-sectional area, it can be set with accuracy matching the welding conditions, and the upset current can be controlled accordingly, greatly improving the welding quality. be able to.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a conventional hydraulic pressure supply circuit of a flash welding machine. FIG. 2 shows another conventional hydraulic pressure supply circuit. FIG. 3 is a conventional hydraulic pressure supply circuit diagram. FIG. 4 is a circuit diagram showing an embodiment of a hydraulic pressure supply circuit according to the present invention. [Explanation of symbols] 1 ... Fixed side clamp cylinder, 2 ... Moving side clamp cylinder, 5, 6 ... Clamp pressure direction switching valve,
8, 22, 23 ... Hydraulic pump, 9 ... Drive cylinder, 10 ...
… Servo valve, 13 …… Direction switching valve, 18,20,21 …… Relief valve, 24 …… One electric motor

Claims (2)

[Scope of utility model registration request] 1. A member to be welded is butt-held by a fixed-side clamp and a movable-side clamp, a welding current is applied to the butt-held end, and both ends reach the welding temperature by Joule heat or flash heating. In a butt welding machine that sometimes applies an upset force to make a pressure contact, a clamp pressure supply circuit that is respectively connected to a hydraulic pump via a direction switching valve on the primary side of the clamp cylinder of the fixed side clamp and the movable side clamp, and A servo pressure supply circuit connected to a hydraulic pump via a servo valve, and a hydraulic pump via a switching valve between the drive cylinder and the servo valve on the primary side of the drive cylinder for advancing the movable side clamp during welding. With the upset pressure supply circuit connected, the hydraulic pumps provided in these separate circuits are linked by a single electric motor. Hydraulic supply circuit of the servo pressure supply circuit and upset pressure second circuit respectively by the relief valve provided on the secondary side of the hydraulic pump pressure of the supply circuit is butt is characterized in that to be set separately welder. 2. The butt welding according to claim 1, wherein the pressure of the clamp pressure supply circuit is controlled by a relief valve provided on the secondary side of the hydraulic pump. Hydraulic supply circuit of the machine.