JPH03169488A - Method for controlling friction welding pressure - Google Patents

Abstract

PURPOSE:To surely perform welding by weakening the holding power of one side at least of a chuck or a clamp during the welding stage and strengthening the holding power during the preliminary pressure stage to perform friction welding. CONSTITUTION:A work 4 at the rotation side is held by the chuck 5 and pressure oil from a hydraulic pump 6 is supplied via a valve 7 to regulate the holding power by the chuck 5. A work 12 at the fixed side is held by jaws provided on a clamping device 3 and the holding power is regulated via a valve 14 by the pressure oil from the hydraulic pump 6. During the welding stage, the holding power of one side at least of the chuck or the clamp is weakened and during the preliminary pressure stage, the holding power is strengthened and the work is held sufficiently without looseness and during welding, an error of moving allowance control caused by looseness is minimized. In addition, the pressurizing force in the direction of a main spindle is increased in order and the generation of a big frictional sound and a stop of rotation due to rotational torque shortage are prevented. By this method, welding can be surely performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a friction welding pressure control method.

[Conventional technology]

In friction welding, it is known to press the workpieces together before heating them by friction. It is also known to control the pressure of the heating process by friction into two stages: preheating pressure and heating pressure.

[Problem to be solved by the invention]

However, since the above-mentioned method does not involve rotation, it is difficult for both the chuck that grips one workpiece and the clamp that grips the other workpiece to grip the workpiece sufficiently without loosening, and it is difficult to hold the workpiece during friction welding. Vibrations caused by the rotation of the main shaft may cause the grip to slip or the jig to loosen.
When controlling the movement of the main shaft image during pressure welding, the above-mentioned loosening is added and there is a problem in that the workpiece cannot be controlled to be accurately twisted.

Furthermore, when pressing a workpiece, if the gripping force on the workpiece is too weak, the workpiece may slip due to the thrust during pressing, making it impossible to grip it properly, and if the gripping force is too strong, the gripping jig may scratch the surface of the workpiece. This may cause problems in friction welding as it may stick or the roundness may deteriorate.

The gripping force in this case varies depending on the workpiece and pressure welding conditions.
There is a problem in that the settings are easy to make mistakes and are time consuming.

Furthermore, if the heating pressure is suddenly increased from the preheating pressure, a loud friction noise may be generated or rotation may stop due to insufficient rotational torque.

If the work is carried out at a higher heating pressure, there is a problem that when a hardenable material such as Cr-Mo steel is pressure-welded, the hardness becomes viscous hardness {vα0)≧400 and hardens. Further, there was a problem in that a very high rotational torque was required during phase control.

Therefore, an object of the present invention is to provide a friction welding pressure control method that can freely control the gripping force and perform reliable pressure welding by controlling the pressure in the main axis direction according to the welding process.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention uses a friction welding method in which one workpiece is fixed and the other workpiece is rotated while applying pressure to each other to weld the two workpieces. This is a friction welding pressure control method in which at least one of the gripping forces is weakened and the gripping force is increased during the preloading process to perform friction welding.

In addition, in the friction welding method in which one workpiece is fixed and the other workpiece is rotated, pressure is applied to press them together, the pressure in the direction of the rotation axis is applied between the preheating pressure and the upset pressure, and the heating This is a friction welding method that changes the pressure in three or more stages: pressure and post-heat pressure.

Furthermore, a friction welding pressure control method is provided in which the post-heating pressure is lower than the heating pressure.

(Function) In the method of the present invention, the gripping force of either the chuck or the clamp is weakened, and the gripping force is strengthened during the preloading period, so that the workpiece is gripped sufficiently without loosening, and the gripping force caused by loosening during pressure welding is reduced. Minimize control errors.

In addition, the pressing force in the direction of the main shaft is gradually increased to prevent generation of large friction noise and rotation stoppage due to insufficient rotational torque.

Alternatively, phase control can be easily performed by setting the final post-heating pressure lower than the heating pressure in the previous step.

[Example] The present invention will be specifically described below based on the apparatus shown in the drawings.

[1] FIG. 1 is a longitudinal sectional side view of a friction welding machine showing one embodiment of the present invention, and FIG. 2 is a front view showing a clamping device.

The friction welding machine A consists of a main shaft housing 2 that is slidably installed on a base 1, and a clamping device 3 that moves on the base 1 in a direction perpendicular to the moving direction of the main shaft housing 2. There is.

The method of the present invention will be specifically explained using the friction welding machine A mentioned above. The workpiece 4 on the rotating side is mounted on the chuck 5 provided on the main shaft M2.
The gripping force of the chuck 5 can be adjusted by supplying pressure oil from a hydraulic pump 6 through a valve 7. The main shaft M2 can slide in a groove 9 provided on the base 1 by a rotor 8 of a cylinder (not shown). In addition, 10 in FIG. 1 is a motor that drives the main shaft 11.

On the other hand, the workpiece 12 on the fixed side is gripped by claws 13.
5 to move both claws 13, 13 and adjust the gripping force. During friction welding, as shown in FIG. ), and use the claws 13, 13 to hold the workpiece 1 on the fixed side.
2 with a predetermined gripping force (30 kgf/cra, cylinder pressure).

Next, when the main shaft housing 2 is moved forward at a fast speed by a cylinder (not shown), the clamp device 3 may be moved forward.

) Both works 4 and 12 come into contact with each other, but when a preset detection pressure is reached, the contact position is confirmed and stored in a storage device (not shown). Further pressurization is continued (main shaft casing 2 continues to move forward), and the preset pressure Po is increased.
o (6 to 20 kgf/mm"), the gripping force of the chuck 5 is increased to 45 kgf/cIIt, and the gripping force of the claws 13.13 is increased to l75 kgf/cd. This increase is caused by the valve 7. Drive motor l for l4 respectively.
6 to increase the supply of pressure oil.

The preload force P0. for about 2 seconds. The main shaft housing 2 is moved backward, the main shaft starts rotating at a predetermined rotation speed (750 rpm), and is moved forward again at a fast speed to reach the contact detection position.

The forward time varies depending on the retreat distance of the main shaft housing 2, but it is approximately 3
It reaches the contact detection position in seconds. After reaching the contact detection position, a preheating pressure P o (0.7 to 2 kgf) is applied to relieve rotational friction and discharge impurities attached to the groove.
/iffI") for about 5 seconds to rotate the rotating side workpiece 4,
Next, both workpieces are heated in earnest and the heating pressure P1 (4 to 10 kgf/
Multiply by mm2). At this heating pressure P1, after about 5 seconds, the post-heating pressure P+' (9 to 12 kgf/mm2)
is carried out for about 5 seconds, the rotation of the main shaft is started to be stopped, and after maintaining the upset pressure Pz (6 to 15 kgf/mm'') for about 5 seconds, the pressure welding is completed.

After that, the main shaft stops pressurizing the pressure generated inside and outside the workpiece after the holding time of the upset pressure P2 has elapsed.
The chuck is opened, and the cutting tool is supplied and deleted at the rotational speed and feeding speed of the cutting tool set in advance.

When the deburring is completed, the claws (clamps) are released and the workpiece is released from the pressure welding machine.

In this embodiment, before applying the preheating pressure P0, the preheating pressure P is
. Contact pressure lower than PL. 0.6 kgf/mm”
It may also be applied at lower pressures.

[2] Next, another example will be explained based on FIG. 4. Preheating pressure P. The steps up to this point are the same as those in the previous example, but the heating pressure P is set at 6 to 12 kgf, which is slightly higher than that in the previous example.
/mm" for about 5 seconds, and then rotated for about 3 seconds at a post-thermal pressure p, L of 2 to 4 kgf/mm",
The spindle starts to stop rotating, and after applying and maintaining the upset pressure P2 for about 5 seconds, the pressure welding is finished.

In addition, when controlling the phase of both workpieces, the post-thermal pressure P1
``Do not apply the upset pressure P2 immediately after ``, but set the post-heat pressure P1'' to a low value to sufficiently heat the pressure contact surface, prevent a sudden temperature drop, lower the frictional rotation torque, and easily perform phase control. . Then, either start stopping the rotation of the spindle before the end of the post-thermal pressure Pl' and match the phase just before the rotation of the workpiece stops, or match the phase immediately after the rotation stops, and after confirming that the phase matching is completed, the upset pressure P
2 and complete the pressure welding.

The rest is the same as in the previous embodiment, so the explanation will be omitted.

[3] In Fig. 3, instead of increasing the gripping force of the chuck or clamp during the excess pressure, the gripping force of the chuck or clamp is increased from the beginning and the gripping force is temporarily increased during the excess pressure. Attenuation is also an embodiment of the invention.

The present invention is particularly effective as a phase control method when fixing one side of a deformed steel hollow part for piping and performing friction welding.

In other words, (1) In the case of piping parts, since they are hollow, the cooling rate at the pressure contact surface before and after the end of rotational heating is greater than in the case of solid materials, and the frictional resistance increases rapidly, so the direction between the parts It becomes difficult to reconcile genders.

In particular, in the case of steel, this becomes difficult when the diameter of the welded portion is 3 inches or more.

(2) When the flange is in pressure contact with another hollow part, the heat capacity of the flange is large, so the cooling rate on the flange side before and after rotation stops becomes large, making phase control difficult.

In the present invention, the heating pressure P1 or post-heating pressure P is 4 kg.
f/mm” or less, and the heating time is preferably 4 seconds or more.

In addition, when the flange and other hollow parts are pressed together, it is effective to make the protrusion length from the flange 5 mm or more.

Example When press-welding flanges on both sides of carbon steel pipe STPG3 8.4BXSch40 Rotation speed N = 75 Orpm Preheating pressure Po = 0.5 Kgf/mm Heating pressure P + = 2 Kgf/mm Post heating pressure P + = 3 Kgf /mm” Upset pressure P z = 1 0 Kgf/mm” Total twist
δ=10+u Heating time t+=6 sec [Effects of the invention] In the present invention, the gripping force of the chuck or clamp is weakened until the preload force is reached, and the gripping force is increased midway through the preload force, so that the workpiece is sufficiently loosened. It can be held without any problems, and it will not come loose during pressure welding work, and errors in displacement control can be minimized. In addition, since the pressure applied in the direction of the main shaft is sequentially changed in three or more stages, large frictional noise and a significant reduction in rotational torque can be achieved, there is no shortage of rotational torque, and rotation does not stop during pressure welding.

In addition, if sufficient time is allowed for post-heat pressure, the hardness of the pressure welded part will remain HvαG)≦30 even if large heating pressure and upset pressure are applied.
0, no abnormal hardness is exhibited, and reliable pressure contact is possible.

Further, since the post-heating pressure is lower than the heating pressure, phase control is easy.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a friction welding machine used in the friction welding method according to the present invention, Fig. 2 is a front view showing the clamp portion, Fig. 3 is an explanatory view showing the process order, and Fig. 4 is FIG. 7 is an explanatory diagram showing another process order. A...Friction welding machine, 1...Base, 2...Main shaft casing,
3... Clamp device, 4... Workpiece, 5... Chuck, 6... Hydraulic pump, 7... Valve, 8...
Rondo, 9... Groove, l 0... Motor, ■ 1... Main shaft, 1 2... Workpiece, 1 3... Claw, 1 4... Valve, 1 5... Cylinder. Meuta Enkan

Claims (3)

[Claims] (1) In the friction welding method, in which one workpiece is fixed and the other workpiece is rotated, the two workpieces are pressed together by applying pressure to each other, and the gripping force of at least one of the chuck or clamp is weakened during the welding process. A friction welding pressure control method characterized in that friction welding is performed by increasing the gripping force during the preloading process. (2) In the friction welding method, in which one workpiece is fixed and the other workpiece is rotated while pressurizing the two workpieces, the pressure in the direction of the rotational axis is applied between the preheating pressure and the upset pressure, and the heating A friction welding pressure control method characterized by changing the pressure in three or more stages of pressure and post-heat pressure. (3) The friction welding pressure control method according to item 2, characterized in that the post-heating pressure is lower than the heating pressure.