JPH0699290A - Friction welding method for copper member and aluminium member - Google Patents

Abstract

PURPOSE:To execute the friction welding of metals having a poor joining property by making an appearance pressurizing force to plural stages by changing the feeding velocity to plural stages during the friction welding. CONSTITUTION:At the time point storing the prescribed energy at the prescribed number of revolution in a fly wheel, a hydraulic cylinder is revolved, the Al alloy material of a un-revolving side is pressed to the copper material of the revolving side with comparative slow speed, the frictional heat is generated and the number of revolution is rapidly reduced. During transmitting from the first stage feeding speed v1 to the second stage feeding speed v2, the delay time of 0.1-1.0sec is set, and the second stage feeding speed v2 is made to the value of 1.5 times larger than the first stage feeding speed v1. Further, the start position t2 is executed during the fly wheel revolving, and the set pressing load is made to be applied at the same time stopping the revolution of the fly wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction welding method for aluminum and its alloys and copper and its alloys.

[0002]

2. Description of the Related Art Many inventions have been applied for patents because friction welding of aluminum and copper is not easily joined as described in some cases (Japanese Patent Laid-Open No. 52-59053). For example, in the aluminum pressure welding connection method using copper (Japanese Patent Laid-Open No. 51-86045), when the upsetting step, which is the second step of pressing to reduce intermetallic compounds, is performed, water is applied to the joint. Coolant bodies such as oil and liquefied gas are enclosed and rapidly cooled to reduce intermetallic compounds generated during cooling. This is because a thin intermetallic compound cannot be uniformly generated on the surfaces to be joined because it is not suitable for the joining conditions, and the friction temperature is increased because it is attempted to obtain by increasing the uniformity. There are drawbacks that workability is deteriorated by using a refrigerant and instability of the joint strength is unavoidable.

According to Japanese Patent Laid-Open Publication No. 54-52648, copper having a high melting point is preheated before friction welding, but since copper having good thermal conductivity is heated, it is bonded at a constant temperature. It is difficult to do so, and since hot ones are handled, productivity is impaired, and instability of joint strength is unavoidable.

Further, in Japanese Patent Laid-Open No. 52-59053, a thermal spray coating or powder of a thermal spray material is adhered to each pressure contact interface between aluminum and copper, and friction heat is used as a medium to make friction adhesion impossible in the past. As described above, the frictional pressure bonding of dissimilar metals has been made possible, which results in joining via a medium, which has a drawback that productivity is impaired and a decrease in strength of the joined portion cannot be avoided.

In the friction welding according to the prior art, it is difficult to directly join dissimilar metals such as aluminum and copper to each other, so that rapid cooling is performed after the friction welding, preheating of the copper side having a high melting point is performed, and further through a medium. However, the cost increases due to the increased number of work processes. Further, there is a problem in that the productivity is hindered by the increase of extra work steps, and the strength and instability of the joint strength are reduced.

In each of JP-A-51-86045 and JP-A-2-30386, the braking method is used, but as an example, the friction welding conditions are shown in graph form as shown in FIG.
In FIG. 3, the pressurization of the upset pressure P2 starts the load at the same time when the rotation is stopped. Upset pressure P shown in FIG.
The start time of 2 is general as shown in the literature (Latest Joining Technology Guide, P306, published by Industrial Technology Service Center, S59). However, in the present invention, there is a problem in that the second stage feed speed cannot be sufficiently joined by increasing the feed speed at the same time as the rotation stop as shown in FIG.

The joint surfaces shown in the above publications are flat on the copper material side and the aluminum alloy material side. Generally, the shape of the joint surface (joint shape) also shows only two types of flat joints or conical slant joints mainly having a pipe even in the literature (friction welding, P109, published by Colon Co., S54). Generally, a flat surface is often used as the shape of the joining surface, but when friction welding is performed in a flat state, the outer diameter side of the pressure-welded product tends to be joined and the inner diameter side is difficult to join. In the case of, there is a drawback that the inner diameter side is not joined.

[0008]

It is difficult to directly bond dissimilar metals such as aluminum and copper by a friction welding method as shown in the above prior art. The following 5
Items can be pointed out.

(A) The ratio of the area actually bonded to the entire bonding surface is called the bonding rate. Generally, it is difficult to obtain a bonding rate of 100%.

(A) In the joined state, when friction welding is performed, the outer diameter side of the product to be pressure-welded tends to be easily joined, and the inner diameter side tends to be difficult to be joined.

(C) The reason for joining is to form an intermetallic compound such as CuAl _{2 at the} joining interface. Joining rate 100%
However, if the intermetallic compound at the joint interface becomes thicker, the strength of the joint decreases, so it is better to make it thinner, but generally the proper thickness is not known.

(D) It is difficult to uniformly form an intermetallic compound on the surfaces to be joined. In particular, if the intermetallic compound is made thin, it is difficult to obtain uniformity under normal friction welding conditions.

(E) Cu at the joint interface under proper friction welding conditions
Even when an intermetallic compound such as Al ₂ is thinly and uniformly produced, it is difficult to obtain the accuracy of the friction welding device which is stably obtained every time.

In the present invention, the flywheel method is selected from the above-mentioned friction welding methods in view of the accuracy of the friction welding apparatus. Furthermore, in order to improve the accuracy, the pressure system is 2
This is limited because stepwise pressurization is better joined, but the pressurization pattern is not stable if the conventional pressurization is changed to two steps. Therefore, FIG. 1 shows the friction welding conditions of the present invention. The apparent pressing force is set to two steps by changing the feed speed during friction welding to two steps while the set pressing force is one step pressing. It is a thing. Moreover, it is 0.1 during the transition from the first stage feed speed v ₁ to the second stage feed speed v ₂ .
A delay time of up to 1.0 second is provided, and the feeding speed v ₂ of the _second stage is a value 1.5 times or more larger than the feeding speed v ₁ of the first stage, and its starting position t ₂ is a fly. While the wheel is rotating and the set load is applied at the same time as the flywheel is stopped, it is possible to perform rational friction welding to improve the strength, reliability and productivity of the joined objects in aluminum and copper. It is intended.

Further, in the case of joining materials having relatively good joining properties, the joining surface of copper is not a flat surface even if the two-step pressing method is not applied, and an arcuate concave curved surface is formed as shown in FIG. By providing it, the same effect as above can be obtained even with the one-stage pressurization method.

[0016]

The friction welding method is roughly classified into two methods, a brake method and a flywheel method.
The condition for obtaining a high tensile strength of 20 kgf / mm ² as the bonding strength is to form a thin intermetallic compound such as CuAl ₂ at the bonding interface at a bonding rate of 100%. Therefore, the friction welding time is 0.5-2.
It is necessary to join in a short time of about 5 seconds. This is because the flywheel method can stably obtain such a short time. In addition, there are two types of pressurization methods in the friction welding method: one-stage pressurization and two-stage pressurization. Each pressurizing method is shown in FIG. 3 and FIG. Generally, a two-stage pressurization system is mainly used in the brake system, and a one-stage pressurization system is mainly used in the flywheel system.

In the two-stage pressurization by the general brake system shown in FIG. 3, the applied pressure is changed in two stages. At the beginning (first stage), a relatively low pressure P ₁ (referred to as heating pressure) is used. Press with. When the two metals come into contact with each other, a predetermined pressure is reached in a short time, and thereafter, the same heating pressure is maintained until immediately before the brake is applied to stop the rotation, and at the same time when the rotation is stopped, a pressure P ₂ (second stage) higher than the heating pressure is reached. It is called up-set pressure). However, changing the pressurizing force in two steps in this manner requires control of two factors of the position and the pressurizing force as a control mechanism, which is inferior in accuracy. As a result, the strength of the joint member varies.
Further, the one-step pressurization shown in FIG. 4 is to maintain the initial applied pressure P ₁ until the rotation is stopped. However, there is a drawback in that the combination cannot be sufficiently joined with the combination in which joining is difficult if the pressing force is set to one step.

Therefore, in the present invention, the pressure is kept constant and
It is characterized in that the apparent pressing force is changed in two steps by changing the speed at which the non-rotating aluminum alloy member is fed and pressed against the rotating copper member in two steps. That is, when the feed speed in the first stage is set to be slow, the feed does not follow the plastic flow of the aluminum alloy, so that the predetermined pressing force cannot be maintained on the friction surface, resulting in a low pressure. Subsequently, the second stage is set at a higher feed speed than the first stage, and the feed follows, so that a predetermined pressure is maintained.

It is not possible to distribute the intermetallic compound thinly and uniformly by simply applying the pressure in two steps, and when changing the feed rate from the first step to the second step, the feed rate is kept constant for a certain period of time. It is necessary to stop with zero between. During the stop of the feed rate, since no burrs are generated, the joining temperature is made uniform and the joining surfaces are softened, and the conditions for uniformly producing the intermetallic compound of copper and aluminum alloy are prepared.

In friction welding of copper and aluminum alloy, A6063-T6 treated material as Al member and C102 as Cu member.
When 0-tempered H is used, the bonding state is the most difficult, and the above means is required. However, when using A1080-0 material as the Al member and C1020-tempered 1 / 4H for the Cu member, the joining ratio on the Cu member side is set to be an arcuate concave curved surface.
0% can be obtained by one-stage pressurization.

[0021]

In the friction welding method according to the present invention, the start position of the feed speed in the second stage is adjusted so that the set pressure is obtained at the same time when the rotation of the flywheel is stopped. This is because the pressure exerts the greatest effect on the joint. As a result,
Since the entire bonding surface is in close contact, it is effective to obtain a bonding rate of 100%. Further, when changing the feed rate from the first stage to the second stage, it is specified that the feed rate is stopped at zero for a certain time in order to obtain a strong joint.

In order to obtain a high tensile strength of 20 kgf / mm ² by friction welding of dissimilar metals of aluminum alloy and copper alloy, the bonding rate is 100% and Cu is bonded to the bonding interface.
It is necessary to thinly form an intermetallic compound such as Al ₂ .
However, the thicker the intermetallic compound at the joint interface, the lower the strength of the joint, so it is better to make it thinner, but if the intermetallic compound is thin, it becomes difficult to form it uniformly on the surfaces to be joined. For this reason, the proper friction welding conditions are limited to a narrow range, which makes the work unstable. The friction welding method of the present invention is limited to the flywheel method because the thickness of the intermetallic compound of copper and aluminum alloy is adjusted by the friction welding time, and the intermetallic compound of copper and aluminum alloy is formed thinly. Therefore, it is necessary to join in a short time of about 0.5 to 2.5 seconds. The flywheel method was selected as a method that can stably and accurately obtain such a short time, and was selected. Also, the limitation to the two-stage pressurization method is 1
This is because a high bonding rate can be stably obtained as compared with the stepwise pressing method. In particular, as a method of obtaining a two-step pressurization, the apparent pressurizing force is changed to two steps by changing the speed at which the non-rotating aluminum alloy member is pressed against the rotating copper member to two steps while keeping the pressurizing force constant. It is changing. This is low because the feed does not follow the plastic flow of the aluminum alloy by setting the feed speed at the first stage to be slow, and a predetermined pressing force cannot be maintained on the friction surface. The 2nd stage has a higher feed rate than the 1st stage (usually 1.5 times the feed rate of the 1st stage).
This is because the feed follows when the number of times is set to 2 times or more), so that a predetermined pressing force can be maintained. As a result, the feed rate is 1
Since it is only a factor, the precision of control can be improved, and the program becomes simple.

The feed speed of the second stage is 1.5 times or more higher than the feed speed of the first stage in order to obtain the strongest and stable strength of the joint portion, and the start position is the flywheel. It is rotating and the set load is applied at the same time as the flywheel rotation is stopped.
There is an effect that can be obtained stably. If the rotation stops and the load does not match, the tensile strength will fluctuate.

In the case of friction welding of copper and aluminum alloy, Al
A6063-T6 treated material as member, C10 as Cu member
It is difficult to obtain the maximum bonding rate of 100% when materials that belong to the harder ones such as 20-Temperature H are used, and the above-mentioned invention conditions are required. However, when an A1080-0 material is used as the Al member, and a relatively soft material such as C1020-tempered 1 / 4H is used for the Cu member, the above-mentioned present invention provides the above-mentioned claims 1, 2 and 3. Needless to say, the bonding rate of 100% can be obtained by making the bonding surface on the Cu member side the arcuate concave curved surface of claim 4.

[0025]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows the results of measurement of the flywheel rotational speed, the pressing force, the deviation, and the temperature of the copper material surface during friction welding of the flywheel method. For friction welding, after fixing the copper material on the rotating side and the Al alloy material on the non-rotating side with chucks, respectively, the spindle motor is rotated to store the rotational energy in the flywheel, and the hydraulic cylinder is reached when the specified rotational speed is reached. When the Al alloy material on the non-rotating side is pressed against the copper material on the rotating side at a comparatively low feed rate by operating, the frictional heat is generated and at the same time the rotational speed is rapidly reduced. When the two metals come into contact with each other, the applied pressure rapidly increases from zero in a time of about 0.2 seconds, but after that, it tends to slightly decrease. Then pressurize at a higher feed rate than the first step. At this time, the feed of the hydraulic cylinder is stopped for about 0.4 seconds when switching from the first stage to the second stage. The resulting pressure is
Although the pressure decreases, the pressure increases again when the second-stage feed starts, and indicates the pressing force set when the rotation stops.

The crossing margin increases with the pressure applied in the first step,
It becomes 0 while the pressure at the time of switching to the second stage pressurization decreases, then increases again with the second stage pressurization, and when the cutoff speed is reached, the fastening part between the flywheel and the spindle motor is changed. The rotation stops all at once by removing it, and after that, there is a two-step tendency in which the crossing margin becomes zero. The temperature of the copper surface shows a maximum value near the rotation stop of the flywheel and then cools rapidly.

As a result of this joining, the joining rate is 98% and the tensile strength is 19.6 kgf / mm ² .

(Embodiment 2) An embodiment in which one-step pressurization is applied by friction welding of a flywheel system will be described with reference to FIG. The hydraulic cylinder is operated to press the non-rotating Al alloy material against the rotating copper material at a predetermined feed rate. When the two joining materials come into contact with each other, the pressure on the pressure contact surface increases to a predetermined pressure in a short time, and after reaching the predetermined pressure, it does not change thereafter. On the other hand, the rotational speed decreases linearly with time. The crossing margin increases unitarily, but when the rotation of the flywheel is stopped, there is a one-step tendency that does not change thereafter. This joining result shows that the joining rate is 46%,
The tensile strength is 9.2 kgf / mm ² .

(Embodiment 3) In the friction welding of copper and aluminum alloy, when A6063-T6 treated material as Al member and C1020-Temperature H of Cu member are used, respectively, the joining state is the most difficult. Therefore, FIG. 7 shows the result of comparison between the two-stage pressurization of the present invention and the general one-stage pressurization performed by friction welding using the respective members by the flywheel method. In the figure, the effect of the rotational energy density on the bonding rate is compared. From the figure, each pressurizing method has an appropriate rotational energy density, but even in that case, the joining rate is 60% or less in the first-stage pressurization, whereas it is 95% to 100% in the second-stage pressurization of the present invention. The values show that the two-stage pressurization shows a stable bonding rate with less variation.

[0030]

According to the present invention, the following effects are listed.

(1) Copper and an aluminum alloy can be directly joined without performing extra work such as rapid cooling after friction welding, preheating of a copper side having a high melting point, and further through a medium.

(2) The pressing force is set to one step and the pressing speed is changed to two steps. The control is simplified with only one factor, resulting in high friction welding accuracy.

(3) By providing a stop time when the pressing speed changes from the first step to the second step, the intermetallic compound at the joint interface can be uniformly formed with an appropriate thickness.

(4) The pressing speed of the second step is set to 1.
The welding rate is 100% or more by adjusting the timing so that the set pressure is applied at the same time as the rotation is stopped.
% Is stably obtained.

(5) According to the above inventions (1) to (4), the tensile strength of the joint portion of 20 kgf / mm ² can be stably obtained.

(6) By forming the joining surface on the copper member side into a concave curved surface, the joining property of friction welding can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a friction welding condition of the present invention as a graph.

FIG. 2 is a sectional view showing a copper-side joint shape of the present invention.

FIG. 3 is an explanatory diagram showing a graph of two-stage pressure friction welding conditions used in a braking system.

FIG. 4 is an explanatory view showing a graph of a one-step pressure friction welding condition used in a flywheel system.

FIG. 5 is a characteristic diagram showing transition of each friction welding condition of the present invention used in Example 1.

FIG. 6 is a characteristic diagram showing transition of each condition of the one-step pressure friction welding used in Example 2.

FIG. 7 is an explanatory view showing the influence of the rotational energy density on the bonding rate in comparison with the two-step pressing according to the present invention and the general one-step pressing.

[Explanation of symbols]

1 ... Arc shape, 2 ... Two-stage pressure according to the present invention, 3 ... One-stage pressure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Osamu Isshiki 1-1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture Inside the Kokubun Plant, Hitachi, Ltd. (72) Inventor Masayoshi Hashiura 1-1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture No. 1 Stock company Hitachi Kokubu factory

Claims (4)

[Claims] 1. The apparent pressing force is changed to two steps by changing the feeding speed to two steps during friction welding of the members to be welded while the set pressing force remains constant. The second stage is performed under the condition of 1.0 mm / sec to 30 mm / sec, the second stage is performed within the condition range of 5.0 mm to 60 mm / sec, and the feed speed of the second stage is the feed of the first stage. From speed 1.
A friction welding method for a copper member and an aluminum member, which is set to a large value of 5 times or more. 2. The method according to claim 1, wherein during the transition from the feed speed of the first stage to the feed speed of the second stage, 0.05.
A friction welding method of a copper member and an aluminum member with a delay time of ~ 1.0 seconds. 3. The first feed speed start position of the second stage is in the flywheel rotation, and the copper member and the aluminum member are loaded with a load set at the same time when the flywheel rotation is stopped. Friction welding method. 4. The joining surface on the copper member side is not a flat surface but a concave curved surface is provided as a joining surface, and the shape of the concave curved surface has a radius equal to or more than ½ of the joining surface distance as a radius. A friction welding method for forming a circular arc shape between a copper member and an aluminum member.