JPH1177338A - Friction joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable joining of high-strength materials with high reliability in a state approximate to room temp. without elevating the temp. of the joining materials themselves as far as possible at the time of friction joining of the high-strength materials. SOLUTION: This method consists in forming joint surfaces by forming the end faces of the two high-strength materials 1, 2 which are the joining materials to roughness of about Rmax<=0.5 μm, more preferably Rmax<=0.1 μm, then bringing the end faces of the two high-strength materials 1, 2 into direct contact with each other. The joining materials are joined with each other by rotating both relatively in a pressurized state to generate the prescribed friction heat on the joint surfaces, then stopping the rotating motion and further applying pressurizing force thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a friction welding method capable of joining at a lower temperature than conventional friction welding. In particular, the present invention relates to regeneration of a monitoring specimen of a nuclear reactor and superconducting wire in addition to carbon steel and low alloy steel. The present invention relates to a friction joining method suitable for joining.

[0002]

2. Description of the Related Art Friction welding is a type of solid-phase welding method in which atoms of a joining material need to be close to the interatomic distance, and the joining surface of the joining material must be plastically deformed. . As one of means for plastically deforming the joining material, a high pressure may be applied to the joining surface. However, if the joining material is a rod, the entire joining material may be buckled and deformed by high pressure. Therefore, the joining surfaces of the joining materials are relatively rotated at a high speed, heated by frictional heat due to frictional contact, and when the joining material is easily deformed, the joining is performed while applying pressure and pressing.

[0003] In the conventional friction welding method, the end face is kept in a machined state, and is pressed as shown by a dotted line B in Fig. 3 showing the time development of the rotation speed, pressure and temperature in friction welding. bonding material mutually contacting the oppositely disposed end faces, and one to rotate the one with relatively predetermined rotational speed N ₁ of the joining material. After reaching a predetermined rotational speed N _1, adding a predetermined frictional pressure P _1, a predetermined friction time ta ₁
When the time elapses, frictional heat is generated. The frictional heat is stopped rotating at both the bonding material becomes Ta reaches an appropriate softened state, then, in a predetermined upset time ta _2, to perform the pressure by applying upset pressure P ₂ 'to each other It was done.

In friction welding, the rise in frictional heat is
Usually, the melting point of the joining material is the limit for the same kind of material, and the lower melting point is the limit for the friction of different materials. Therefore,
In the conventional friction joining method, when the two joining materials are high-strength materials such as steel materials, the temperature of the joining materials has reached 800 ° C. or more. Furthermore, according to the conventional friction joining method, it is easy to join relatively soft materials such as aluminum and copper, but it is difficult to join relatively high-strength materials such as titanium, stainless steel and ceramics. Was. In addition, oxides, dirt, and the like that hinder the bonding were generated at the bonding portions.

Therefore, Japanese Patent Application Laid-Open No. 3-184683 has proposed the following friction joining method. That is, first, as shown in FIG. 6, one of the bonding materials 17 is gripped by the rotary chuck table 4, the soft intermediate material 19 is gripped by the fixed chuck table 5, and the end face 17 a of the one bonding material 17 is The contact surface 12 is brought into contact with the end face 19a,
a is hermetically surrounded by an airtight chamber 14;
The inside of the airtight chamber 14 is maintained in an inert atmosphere and the arrow P
As shown in the figure, pressure is applied to the bonding surface 12a, and the bonding material 17 is pressed.
Were rotated and joined by frictional heat. Next, as shown in FIG. 7, the other joining material 18 is gripped by the fixed chuck table 5, and the other end surface 19 b of the intermediate material 19 joined to the one joining material 17 is brought into contact with the end surface 18 a of the other joining material 18. I let it. Further, this joint surface 12b is connected to the airtight chamber 1
4, the inside of the airtight chamber 14 is kept in an inert atmosphere, pressurized toward the bonding surface 12b as indicated by an arrow P, and the bonding is performed by frictional heat while the bonding material 17 is rotated. This enabled joining of high-strength materials that were difficult to perform.

As another pressure welding method, diffusion bonding for bonding materials at a low temperature has also been performed. In this method, after the bonding surface is finished to a mirror surface, the bonding surface is cleaned by irradiating an Ar ion beam in a vacuum, and bonding is performed by applying pressure. Further, they may be joined by soldering. Further, there is also a method in which a bonding surface is coated with a soft material in advance before bonding and the bonding is performed in the atmosphere as disclosed in Japanese Patent Application No. 8-3554537.

[0007]

The above-mentioned conventional method of the type described above has the following problems. That is, the rise in frictional heat is generally limited to the melting point of the joining material for the same type of material,
In the friction of different materials, the lower melting point is the limit. Therefore, in the conventional friction welding, when the two joining materials are high-strength materials such as steel materials, the temperature of the joining materials reaches 800 ° C. or more. As a result, the steel material is transformed to change properties such as strength, and easily deformed by a small force.

Further, in the case described in the above-mentioned Japanese Patent Application Laid-Open No. 3-184683, since the joining operation needs to be performed in a vacuum chamber, a vacuuming operation is required before joining each time. It takes a lot of time, the workability is poor, and the cost is disadvantageous. Also,
According to the low-temperature diffusion bonding method described above, not only a large-scale special bonding device is required, but also it is impossible to bond a high-strength material such as a steel material.
Is limited to the joining of soft materials. Also,
Although soldering is a simple method, it has a problem that it cannot be applied to joining structural materials due to low joining strength. on the other hand,
As disclosed in Japanese Patent Application No. 8-3554537, the method of coating the end face with a soft material in advance can be bonded in the air, but the coating process requires time.

An object of the present invention is to solve the above problem by frictionally joining a high-strength material without increasing the temperature of the joining material itself as much as possible, while maintaining the reliability of the high-strength material near room temperature. An object of the present invention is to provide a friction joining method that enables high joining.

[0010]

SUMMARY OF THE INVENTION According to the present invention, two joining materials are relatively rotated in a pressurized state, and after a predetermined frictional heat is generated on the joining surface, the rotating motion is stopped to further apply a pressing force. In addition, in the friction joining method for joining the joining materials, the end surface roughness of the two high-strength materials as the joining material is reduced by about R
max 0.5 μm or less, preferably Rmax 0.1 μm
After forming the joining surface in the following, the end surfaces of the two high-strength materials are brought into direct contact with each other, and the two are relatively rotated in a pressurized state to generate a predetermined frictional heat on the joining surface. The rotational members are stopped, and a pressing force (upset pressure) is further applied to join the joining materials to each other.

In the friction joining method according to the present invention, one of the two high-strength materials, which is a joining material, is fixed, and the other is rotated by a driving device to bring the two high-strength materials into direct end-face contact. When the joint between both joining materials reaches a predetermined temperature, the rotation is stopped using a brake, and the upset pressure is further reduced. Brake type welding method in which both joining materials are joined by adding a joint, or one of the joining materials is fixed and the other is attached to a shaft with a flywheel and rotated, and the frictional part consumes rotational energy and rotates And a variety of friction welding methods such as a flywheel type welding method in which an upset pressure is applied after the rotation is stopped.

High-strength materials include materials having strength against plastic deformation, such as carbon steel, low alloy steel, structural alloy steel, tool steel, stainless steel and other steel materials, cemented carbide, cermet, and polycarbonate. And synthetic resins such as polyacetal. Further, it goes without saying that the friction joining method of the present invention includes a case where different kinds of high-strength materials are joined by friction.

[0013]

According to the present invention, prior to the joining in the joining step described above, the joining is easily performed even in the air by precision polishing in advance. Therefore, the joining surface is surrounded by an airtight chamber or the like, and friction joining is performed under an inert atmosphere. It is not necessary to perform the operation, and the operation can be easily performed with a simple device. Therefore, according to the friction joining method of the present invention, first, the end faces of the high-strength joining material are precisely polished, then the two joining materials are arranged to face each other, and the two high-strength materials are brought into direct end-face contact and joined. Form a surface. Next, when the joining materials are pressed against each other at a predetermined friction pressure and then relatively rotated, the polished portion of the joining surface reaches a softened state early due to frictional heat. At this time, the rotation is stopped, and the upset pressure is further increased to frictionally join the joining materials.

As a technique similar to the present invention, the present applicant first coats an end surface of a joining material with a soft material of Au, Ag, or Cu to form a joining surface, and then enters the friction joining step. A friction joining method characterized by deforming and joining only the soft material is proposed (Japanese Patent Application No. 8-3545).
37, non-known prior application technology). However, in the prior art, the joining materials are not directly in contact with each other, but are joined via a soft material, so that the strength of the joining material portion is reduced. On the other hand, according to the present invention, since the joining materials are not joined via the soft material but are in direct contact with each other, the strength of the joining material portion does not decrease.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only. FIG. 1 is an explanatory view of an example of a friction welding apparatus according to an embodiment of the present invention, and the apparatus is indicated by reference numeral 16. FIG. 2 is a side view of a main part showing a joining state at the time of friction joining according to the present invention, and FIG. 3 is a graph showing rotation speed, pressure, and temperature over time of the friction welding method of the present invention and the conventional example. It is a friction welding cycle diagram which shows a change. In FIG. 1, the friction welding device 16 includes a rotary chuck table 4 that is driven to rotate by a motor 3 via a pulley / belt 8 and a rotating shaft 9. Is gripping. Further, the rotary chuck table 4
A stationary chuck table 5 is disposed to face the other and grips the other high-strength material 2.

The fixed chuck base 5 is mounted on a base 6, and is provided with an arrow 1 by a pressing means 7 comprising a hydraulic cylinder 7a and a piston 7b inserted through the hydraulic cylinder 7a.
As shown by reference numeral 1, the base 6 can be slid. For this purpose, an end surface 1a of the high-strength material 1 and an end surface 2a of the high-strength material 2 are brought into contact with each other to form a joint surface 12,
By rotating the chuck of the rotary chuck table 4 via the electric motor 3, frictional heat can be generated on the joint surface 12. A brake 10 is installed around a rotary shaft 9 coaxial with the rotary chuck table 4 and stops rotating when the joint surface 12 of the high-strength materials 1 and 2 reaches a predetermined softened state.
Further, an upset pressure is further applied by the pressing means 7, so that the high strength materials 1 and 2 can be joined.

A first embodiment of the friction joining method of the present invention will be described. First, as shown in FIG. 2, a high-strength material (joining material)
16 mmφ × 40 mmL round bar (low alloy steel (example: JIS G 3120 SQV2A material)) 1 and 1 as 1 and 2
Using a square bar (carbon steel material) 2 of 0 mm square × 40 mmL, Rmax roughness 0.1 μm to 0.03 μm is applied to the end surfaces 1 a and 2 a.
Prepare the processed one. Next, the rotary chuck table 4
The round bar 1 made of the above-mentioned steel material is attached to the above. Subsequently, the other carbon steel square bar 2 is attached to the fixed chuck base 5, and the two joining materials 1 and 2 are opposed to each other. Further, the hydraulic chuck 7a and the piston 7b, which are the pressing means 7, are driven to move the fixed chuck base 5 on the base 6 to form a contact surface. Next, the rotation speed N and the pressure P ₁ are changed by the pressing means 7 as shown by the solid line A in FIG.

That is, in the friction joining method of the present embodiment, the end faces 1a, 2a of the two joining materials 1, 2 are processed to have a Rmax roughness of 0.1 μm to 0.03 μm, and then the joining materials 1, 2 the end faces into contact with each other, rotating with a small rotational speed N than the bonding material 1 rotational speed N ₁ of the prior art. After reaching a predetermined number of revolutions N, a predetermined friction pressure P ₁ is applied, and when a predetermined friction time t ₁ elapses, frictional heat is generated. The frictional heat is stopped rotating at both bonding materials 1 and 2 becomes T has reached the appropriate softened state, then, in a predetermined upset time t _2, performing bonding by mutually make a upset pressure P ₂ .

Accordingly, in the friction welding cycle diagram of FIG. 3, when comparing the friction joining method of the present invention indicated by the solid line A with the conventional friction joining method indicated by the dotted line B, the number of revolutions is equal to the number of revolutions of the prior art. friction contact with the region of small rotational speed N than _1, since the soft material in the frictional heat is softened in a short time, to stop the rotation in a short period of time t ₁ compared to the conventional friction time ta _1. At this time, the bonding is performed at a temperature T lower than that of the conventional Ta. For this reason, the press-contact time is ta ₁ + ta ₂ in the conventional example, but is t ₁ + t _{2 in the} present invention.
And the bonding is completed in a very short time. Incidentally, there is no significant difference in the frictional pressure P ₁ and the upset pressure P _2.

Therefore, according to the present embodiment, the dotted line B in FIG.
The heating temperature can be greatly reduced compared to the conventional technology shown in the above, and in friction welding of high strength materials, the high strength materials can be kept close to room temperature without raising the temperature of the joining materials themselves as much as possible. Enables highly reliable bonding.

FIG. 5 is a graph for confirming the effect of this embodiment. The graph of FIG. 5 shows the surface temperature distribution of the square bar 2 at the position of 2 mm and 4 mm away from the joint surface and the joint surface. The temperature measurement position is shown at the upper right of this graph. In the case of this embodiment, 80 as the pressure P ₁
Rotate in the direction of arrow 13 while changing from 0 to 50 kgf. The rotation speed was 3,600 rpm.

Here, the deviation refers to the length of wear of the joining material 1 (high-strength material) and the joining material 2 (square bar) when "burrs", which are bulges on the joining surface, occur. more white is (wear in friction time ta ₁₎ white friction near the upset near white (wear in upsetting time ta ₂₎
And the sum of the two is said to be all-out.

In FIG. 5, the conventional technology in which the end surfaces 1a and 1b are machined (roughness Rmax: 3 μm) has a large total deviation at the time of joining as a maximum of 3.28 mm and an angle 2 mm away from the joining surface. The surface temperature of the rod 2 is as high as 860 ° C. On the other hand, in the case of precision polishing (Rmax = 0.1 μm), the total deviation at the time of joining is 0.46 mm at the maximum and the surface temperature is around 410 ° C.
= 0.03 μm), a square rod 2 with a maximum total deviation of 0.17 mm at the time of joining and 2 mm away from the joining surface.
Has a surface temperature of about 260 ° C. and a bonding temperature of about 30 ° C.
The temperature could be lowered to 0 ° C or less.

As a result of an impact test of these joining materials 1 and 2 at 100 ° C., it was confirmed that toughness of 20 kgf-m or more was obtained, and that they had the same properties as the base material.

Next, a comparative example of the friction joining method of the present invention will be described with reference to FIG. FIG. 4 shows the device of FIG.
A hermetic chamber 14 is provided surrounding 2. The airtight chamber 14 is supported on the base 6 by legs. Further, the air-tight chamber 14 contains He or Ar.
And the like are introduced from an inert gas source 15. The same effect as that of the present invention could be obtained by using the friction pressure welding device 16 having such a structure and joining it in an inert atmosphere by a method substantially similar to that of the first embodiment.
Therefore, the embodiment shown in FIG. 1 can obtain the same effect as the comparative example shown in FIG. 4 in which the bonding surface 12 is surrounded by the airtight chamber 14 and the inside of the airtight chamber 14 is kept in an inert atmosphere.

[0026]

As described above, according to the friction joining method of the present invention, the joining end face of the joining material is precisely polished or ultra-precision polished, so that joining can be performed at a lower temperature than conventional friction welding. , And the characteristics of the high-strength material are not lost. Further, according to the present invention, since the joining materials are in direct contact with each other, not joined via the soft material, the strength of the joined portion does not decrease. Further, it is not necessary to surround the joint surface with the airtight chamber and keep the inside of the airtight chamber in an inert atmosphere, so that a device having a simple structure can be used. In addition, a troublesome operation for creating an inert atmosphere is not required, a supply path for an inert gas, a vacuum pump, and the like are not required, and friction joining of a high-strength material can be performed at low cost. Note that the present invention does not exclude application to a device in which the joint surface is surrounded by an airtight chamber and the inside of the airtight chamber is maintained in an inert atmosphere, and such a device is naturally included in the technical scope of the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a friction welding device used in an embodiment of the present invention.

FIG. 2 is an enlarged side view of a joining portion of FIG.

FIG. 3 is a friction welding cycle diagram of the present invention (solid line A) and a conventional example (dotted line B).

FIG. 4 is an explanatory view of a friction welding device used as a comparative example of the present invention.

FIG. 5 is a graph showing the relationship between the maximum heating temperature of the heat-affected zone and the total margin in the present invention and the conventional method.

FIG. 6 is an explanatory view showing a first joining step of the conventional friction welding method.

FIG. 7 is an explanatory view showing a second step of the conventional friction welding method shown in FIG.

[Description of Signs] 1, 2 High-strength material (joining material) 1a, 2a End face 4 Rotating chuck table 5 Fixed chuck table 6 Base 7 Pressing means 7a Hydraulic cylinder 7b Piston 9 Rotating shaft 10 Brake

Claims (1)

[Claims] 1. A method according to claim 1, further comprising: rotating the two joining members in a pressurized state to generate a predetermined frictional heat on the joining surface; In the friction joining method for joining the two, the end surface roughness of the two high-strength materials as joining materials is set to about Rmax
After forming a joining surface with 0.5 μm or less, preferably Rmax 0.1 μm or less, the end surfaces of the two high-strength materials are brought into direct contact with each other, and both are relatively rotated in a pressurized state,
A friction joining method comprising joining the joining materials by generating a predetermined frictional heat on the joining surface, and then stopping the rotational movement and further applying a pressing force.