Linear friction joining device

Abstract

The present invention provides a linear friction joining device that is compact and inexpensive. In addition, provided is a linear friction joining device that is suitable for joining different materials and manufacturing a large-sized structure. The linear friction joining device according to the present invention for joining one member and another member, is characterized by: being provided with a holding mechanism that causes the one member to abut against the other member so as to form a joined interface, a vibration mechanism that causes the one member and the other member to be relatively excited, and a pressing mechanism that applies joining pressure to the joined interface substantially perpendicularly to the joined interface; and using an electric motor as a driving source of the vibration mechanism.

Description

Technical Field

[0001] The present invention relates to a linear friction joining apparatus that joins workpieces using frictional heat.

Background Art

[0002] With the increase in strength of metal materials such as steel and aluminum alloys, a significant decrease in strength at the joint that determines the mechanical properties of the joined structure has become a serious problem. In contrast, in recent years, a solid-phase joining method in which the maximum temperature reached during joining does not reach the melting point of the workpiece and the decrease in strength at the joint is smaller compared to conventional fusion welding has attracted attention and is rapidly being put into practical use.

[0003] In particular, "linear friction joining" in which the workpieces are joined by linearly reciprocating them in a state of being in contact with each other does not require a tool for pressing into the workpiece like friction stir joining, and thus can be easily applied to high-melting-point and high-strength metals such as steel and titanium. Development of a linear friction joining apparatus used for such linear friction joining is underway.

[0004] For example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2017-42772), a first holding part that holds a first workpiece, a first actuator that can vibrate the first holding part, a second holding part that holds a second workpiece, a second actuator that can press the second workpiece against the first workpiece, and a control part that drives and controls the first actuator and the second actuator are provided. The control part vibrates the first workpiece in a direction orthogonal to the axis of the second workpiece by the first actuator while pressing the second workpiece against the first workpiece, presses the second workpiece against the first workpiece with a first pressing load for a preset low load time from the start of joining by the second actuator, and controls so as to press the second workpiece against the first workpiece with a second pressing load greater than the first pressing load after the low load time has elapsed. A linear friction joining apparatus is disclosed.

[0005] In the linear friction welding device described in the above Patent Document 1, since the pressing load by the second actuator is reduced for a preset low load time from the start of linear friction welding, the vibration load at the start of linear friction welding, which requires the most vibration load, can be suppressed, the size of the first actuator can be reduced, the size of the device itself can be reduced, and an excellent effect of reducing the manufacturing cost can be exhibited.

[0006] Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2018-75591), a linear friction welding device having a pressing device for pressing one member against the other member and a vibration device for vibrating the one member relative to the other member, a position sensor for detecting the displacement amount of the other member in the pressing direction, and a control device for controlling the vibration device so as to switch the amplitude for vibrating the one member from a first amplitude to a second amplitude smaller than the first amplitude based on the detection result of the position sensor are disclosed.

[0007] In the linear friction welding device described in the above Patent Document 2, the displacement amount of the other member pressed against one member in the pressing direction is detected, and based on the displacement amount, the amplitude for vibrating one member is switched from a first amplitude to a second amplitude smaller than the first amplitude. In this way, by detecting the displacement amount of the other member, that is, the burn-off amount, by the position sensor, the vibration amplitude can be switched to a smaller value immediately before the end of the linear friction welding process. When the vibration amplitude becomes smaller, the burn-off amount per unit time (burn-off speed) becomes smaller. As a result, even if the number of vibrations varies slightly when the vibration stops, since the burn-off speed is small, the variation in the burn-off amount becomes small. Therefore, it is said that a decrease in dimensional accuracy due to variation in the number of vibrations can be suppressed.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

[0009] Linear friction joining is a joining method having many advantages, and linear friction joining devices have also been improved from various viewpoints. However, due to their complex mechanisms, linear friction joining devices are expensive and large-sized, and despite many applications being envisioned, the technical barriers to introduction are becoming higher.

[0010] In the linear friction joining device disclosed in Patent Document 1 above, the size reduction of the device itself and the reduction of manufacturing costs are achieved by suppressing the vibration load. In the linear friction joining device disclosed in Patent Document 2 above, by switching the vibration amplitude to a small value immediately before the end of the linear friction joining process, the suppression of the reduction in dimensional accuracy due to variations in the number of vibrations is attempted. However, in terms of using a complex hydraulic mechanism with an accumulator in the vibration mechanism, it is the same as the conventional linear friction joining device, and it is ultimately difficult to significantly reduce the cost and size of the linear friction joining device.

[0011] In view of the problems in the prior art as described above, an object of the present invention is to provide an inexpensive and compact linear friction joining device. Another object of the present invention is also to provide a linear friction joining device suitable for joining different materials and manufacturing large-sized structures. [Means for Solving the Problems]

[0012] In order to achieve the above object, the present inventor conducted intensive research on each component of the linear friction joining device based on the joining conditions of linear friction joining that can obtain a good joint. As a result, the inventor found that it is extremely important to use a high-performance electric motor as the drive source of the vibration mechanism, and thus arrived at the present invention.

[0013] That is, the present invention is A linear friction joining device for joining one member and another member, a gripping mechanism for bringing the one member and the other member into contact with each other to form a joint interface, a vibration mechanism for relatively vibrating the one member and the other member, and a pressing mechanism for applying a joining pressure substantially perpendicular to the joint interface, and using an electric motor as a drive source of the vibration mechanism, characterized in that it provides a linear friction joining device.

[0014] Further, the present invention is a linear friction joining device for joining one member and another member, a gripping mechanism for bringing the one member and the other member into contact with each other via an insert material to form a joint interface (1) where the one member and the insert material are in contact with each other and a joint interface (2) where the other member and the insert material are in contact with each other, a vibration mechanism for relatively vibrating the insert material between the one member and the other member, and a pressing mechanism for applying a joining pressure substantially perpendicular to the joint interface (1) and the joint interface (2), and using an electric motor as a drive source of the vibration mechanism, characterized in that it also provides a linear friction joining device.

[0015] Since the size of the insert material can be easily controlled (miniaturized) compared to the joined material, a more suitable linear friction joining device can be obtained when using an electric motor that is weaker than a hydraulic mechanism. Here, by making the insert material the same material as the joined material, even a large joint structure can be easily manufactured. Further, when performing dissimilar material joining, an insert material of an appropriate material can be selected in view of the joinability with each joined material.

[0016] In the linear friction joining device of the present invention, an electric motor is used as a drive source for the vibration mechanism. In a conventional linear friction joining device, a complicated hydraulic mechanism involving an accumulator called an accumulator is used. Since a large number of high-pressure tanks and hydraulic pumps are required for this mechanism, the device inevitably becomes larger in size and the price also increases. The accumulator is used for the purpose of sliding the workpieces at high speed with a large force. However, when the present inventor conducted linear friction joining experiments on various workpieces (materials, shapes, and sizes), it became clear that a joining device can be sufficiently established even by driving with an electric motor. Further, in the hydraulic mechanism, maintenance such as regular oil replacement is indispensable, but it is not required for an electric motor, and the use of an electric motor is also advantageous in terms of running costs. From the viewpoint of accurately controlling the moving speed, position of the workpieces during linear friction joining, and the force applied to the workpieces, it is preferable that the electric motor be an electric servo motor.

[0017] Further, by using an electric servo motor as a drive source for the vibration mechanism, within the range of the capabilities of the electric servo motor, the amplitude and frequency of sliding can be set to desired values.

[0018] In the linear friction joining device of the present invention, it is preferable to convert the rotational motion of the electric motor into a linear motion using a ball screw or a feed screw. By using a ball screw or a feed screw, high repetitive position accuracy can be achieved. Further, it is possible to generate the maximum pressing force at all stroke positions, and linear friction joining can be performed based on a more accurate sliding operation.

[0019] Further, in the linear friction joining device of the present invention, it is preferable to convert the rotational motion of the electric motor into a linear motion using any one of a crank mechanism, a link mechanism, and a knuckle mechanism, or a combination thereof. These mechanisms are simpler than the mechanism using a ball screw, and an inexpensive linear friction joining device can be realized.

[0020] In addition, in the linear friction joining device of the present invention, when an electric servo motor is used as the drive source of the vibration mechanism, it is preferable to make the amplitude and / or frequency of the vibration by the vibration mechanism variable. By making the amplitude and / or frequency of the vibration variable, it is possible to cope with the joining of various workpieces with one linear friction joining device.

[0021] In addition, in the linear friction joining device of the present invention, it is preferable to fix the amplitude and / or frequency of the vibration by the vibration mechanism. When an electric servo motor is not used as the drive source of the vibration mechanism, it is difficult to make the amplitude and / or frequency of the vibration by the vibration mechanism variable. On the other hand, when the workpiece is determined, the linear friction joining conditions are basically the same. That is, by using an electric motor having a simple mechanism and fixing the amplitude and / or frequency of the vibration by the vibration mechanism, a linear friction joining device for mass production that is cheaper and smaller can be realized. Here, "fixing the amplitude and / or frequency" is a concept including having a plurality of values (for example, a combination of amplitudes and frequencies of three patterns).

[0022] In addition, in the linear friction joining device of the present invention, it is preferable that the amplitude of the vibration by the vibration mechanism is 0.1 to 5 mm and the frequency is 10 to 100 Hz. By setting the amplitude of the vibration to 0.1 to 5 mm and the frequency to 10 to 100 Hz, linear friction joining can be achieved even when an electric motor is used as the drive source of the vibration mechanism. Here, when the amplitude is increased, the upper limit of the frequency decreases, but within the above numerical range, it can be realized by using an electric motor.

[0023] Furthermore, in the linear friction joining device of the present invention, it is preferable that the pressing force by the pressing mechanism is 1.5×10 4 kg or less. It is necessary to slide by the vibration mechanism in a state where a pressing force is applied to the workpiece or the insert material. When the pressing force is 1.5×10 4By setting it to less than [[kg]], even when an electric motor is used as the drive source of the vibration mechanism, the sliding required for linear friction joining can be achieved. Note that the force required to slide the material to be joined or the insert material can also be adjusted according to the linear friction joining conditions such as amplitude and / or frequency. Further, when it is desired to further reduce the force for sliding the material to be joined or the insert material, the material to be joined or the insert material may be softened by using external heating by various conventionally known methods.

Advantages of the Invention

[0024] According to the present invention, an inexpensive and compact linear friction joining device can be provided. Further, according to the present invention, a linear friction joining device suitable for joining different materials and manufacturing large structures can also be provided.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0026] Hereinafter, representative embodiments of the linear friction joining device of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. In the following description, the same or corresponding parts may be denoted by the same reference numerals, and duplicate descriptions may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions of each component shown and their ratios may be different from the actual ones.

[0027] (1) Linear friction welding apparatus for vibrating a workpiece Fig. 1 shows a schematic diagram illustrating the situation during linear friction welding. Linear friction welding is a solid-state welding method that uses frictional heat generated when workpieces are rubbed against each other in a linear motion as the main heat source. By discharging the softened material from the joint interface as burrs during heating, oxide films and the like formed on the joint interface are removed, and the joint can be obtained by bringing the newly formed surfaces into contact with each other.

[0028] The linear friction welding apparatus of the present invention is an apparatus for achieving the welding process shown in Fig. 1, and includes a gripping mechanism for bringing one member into contact with the other member to form a joint interface, a vibration mechanism for relatively vibrating one member and the other member, and a pressing mechanism for applying a welding pressure substantially perpendicular to the joint interface, and is characterized in that an electric motor is used as a drive source of the vibration mechanism.

[0029] Mechanisms other than the vibration mechanism using an electric motor are not particularly limited as long as the effects of the present invention are not impaired, and mechanisms used in various conventionally known linear friction welding apparatuses can be used. In addition, for the control of the vibration mechanism using an electric motor, for example, a control system of a press machine using a conventionally known electric motor can be used.

[0030] It is preferable to use an electric servo motor as the electric motor. By using an electric servo motor, the amplitude and frequency of vibration can be set to desired values within the capabilities of the electric servo motor.

[0031] In order to convert the rotational motion of the electric motor into a linear motion, it is preferable to use a ball screw or a feed screw. By using a ball screw or a feed screw, high repetitive positioning accuracy can be achieved. In addition, the maximum pressing force can be generated at all stroke positions, and linear friction welding can be performed based on a more accurate sliding operation.

[0032] In addition, by using any one of a crank mechanism, a link mechanism, and a knuckle mechanism, or a combination thereof, to convert the rotational motion of the electric motor into linear motion, an inexpensive linear friction joining device can be realized.

[0033] Further, by fixing the amplitude and / or frequency of vibration by the vibration mechanism and using an electric motor having a simple mechanism, a linear friction joining device for mass production that is cheaper and smaller can be realized.

[0034] The amplitude of vibration by the vibration mechanism is preferably 0.1 to 5 mm, more preferably 0.5 to 3 mm, and most preferably 1 to 2 mm. Also, the frequency of vibration by the vibration mechanism is preferably 10 to 100 Hz, more preferably 15 to 75 Hz, and most preferably 25 to 50 Hz. When the amplitude is increased, the upper limit of the frequency decreases, but within the above numerical range, it can be realized using an electric motor. In particular, by setting the amplitude to 1 to 2 mm and the frequency to 25 to 50 Hz, in addition to being able to fully utilize the characteristics of the electric motor, it is possible to cope with the joining of a wide variety of materials to be joined.

[0035] The pressing force by the pressing mechanism is preferably 1.5×10 4 kg or less, more preferably 1.0×10 4 kg or less, and most preferably 0.5×10 4 kg or less. By setting the pressing force within these ranges, even when an electric motor is used as the drive source of the vibration mechanism, the sliding necessary for linear friction joining can be achieved. Here, the force required to slide the material to be joined or the insert material at high speed may be assumed to be about the pressing force to 2 / 3 of the pressing force.

[0036] (2) Linear friction joining device for vibrating the insert material (center drive method) In the linear friction device of the present invention using the center drive method, one member and the other member are brought into contact with each other via an insert material, and a joined interface (1) where the one member and the insert material are in contact, and a joined interface (2) where the other member and the insert material are in contact are formed. The device includes a gripping mechanism, a vibration mechanism for relatively vibrating the insert material between the one member and the other member, and a pressing mechanism for applying a joining pressure substantially perpendicular to the joined interface (1) and the joined interface (2). An electric motor is used as the drive source of the vibration mechanism.

[0037] Even when the center drive method is adopted, mechanisms other than the vibration mechanism using an electric motor are not particularly limited as long as the effects of the present invention are not impaired, and mechanisms used in various conventionally known linear friction joining devices can be used. In addition, for the control of the vibration mechanism using an electric motor, for example, a control system of a press machine using a conventionally known electric motor can be used.

[0038] In the center drive method, since the insert material needs to be moved at high speed, a gripping mechanism for fixing the insert material is required. However, the features regarding the vibration mechanism and the pressing mechanism are basically the same as those in the case of moving the joined material at high speed described above. On the other hand, since the insert material can be relatively easily miniaturized, it has an advantageous configuration in a linear friction joining device using a relatively weak electric motor compared with a hydraulic mechanism. Further, when the center drive method is used, it is preferable to provide a pressing mechanism capable of applying different joining pressures substantially perpendicular to the joined interface (1) and the joined interface (2). Although details will be described later, by applying different joining pressures substantially perpendicular to the joined interface (1) and the joined interface (2), a good dissimilar material linear friction joining joint can be obtained.

[0039] Hereinafter, taking the case of controlling the joining temperature for dissimilar material joining as an example, a specific example of the linear friction joining device of the present invention using the center drive method will be described. The linear friction joining device of the present invention can realize the following linear friction joining.

[0040] The relationship between the situation during dissimilar material joining and the joining temperature is schematically shown in Fig. 2. One member 2 and the other member 4 with different compositions are brought into contact via an insert material 6, and a joined interface (1) where one member 2 and the insert material 6 are in contact, and a joined interface (2) where the other member 4 and the insert material 6 are in contact, are formed.

[0041] In this state, by repeatedly sliding the insert material 6 up and down, frictional heat is generated at the joined interface (1) and the joined interface (2). Here, when controlling the joining temperature at each joined interface in dissimilar material joining, a joining pressure (1) is applied substantially perpendicular to the joined interface (1), a joining pressure (2) is applied substantially perpendicular to the joined interface (2), and the joining pressure (1) and the joining pressure (2) are set to different values. The graph shown on the upper side of Fig. 2 schematically shows the temperature dependence of the strength of one member 2, the other member 4, and the insert material 6. When one member 2 and the other member 4 have the temperature dependence of strength as shown in Fig. 2, since there is no temperature at which the strengths of one member 2 and the other member 4 are the same, it is not possible to deform one member 2 and the other member 4 to the same extent at the joined interface. On the other hand, by using the insert material 6 having the temperature dependence of strength as shown in Fig. 2, at the joined interface (1) and the joined interface (2), a good joint can be obtained by the contact of the newly formed surfaces with each other. When one member 2, the other member 4, and the insert material 6 are the same, the joining pressure (1) and the joining pressure (2) are set to the same value.

[0042] More specifically, the line showing the temperature dependence of the strength of the insert material 6 has an intersection with the line showing the temperature dependence of the strength of one member 2 and the line showing the temperature dependence of the strength of the other member 4. Here, at the joined interface (1), the joining pressure (1) corresponding to the intersection of one member 2 and the insert material 6 may be set, and at the joined interface (2), the joining pressure (2) corresponding to the intersection of the other member 4 and the insert material 6 may be set.

[0043] The relationship of the temperature dependence of the strength shown in Fig. 2 is an example. For example, a combination of a workpiece to be joined and the insert member 6 having the temperature dependence of the strength as shown in Fig. 3 may be used. The insert member 6 only needs to have an "intersection" with one member 2 and the other member 4, and can be selected from various conventionally known metal materials. Although not limited to this, generally, many metals having a bcc crystal structure have a large temperature dependence of strength and are candidates for insert materials when joining metals having an fcc crystal structure. On the other hand, when joining metals having a bcc crystal structure, metals having an fcc crystal structure are candidates for insert materials.

[0044] Fig. 4 is a schematic diagram showing the joining process when joining dissimilar materials using a center drive type linear friction joining device. A first step of bringing one member 2 and the other member 4 into contact with each other via the insert member 6 to form a joined interface (1) where one member 2 and the insert member 6 are in contact and a joined interface (2) where the other member 4 and the insert member 6 are in contact; a second step of applying a joining pressure (1) substantially perpendicular to the joined interface (1) and a joining pressure (2) substantially perpendicular to the joined interface (2), setting the joining pressure (1) and the joining pressure (2) to different values, generating frictional heat by the sliding of one member 2, the other member 4, and the insert member 6, raising the temperature of the joined interface (1) and the joined interface (2), and discharging burrs 8 from the joined interface substantially parallel and substantially perpendicular to the sliding direction; and a third step of stopping the sliding to form a joined surface. The joining temperature can be accurately controlled by the joining load applied substantially perpendicular to the joined interface. Hereinafter, each step will be described in detail.

[0045] (1-1) First step The first step is a step of bringing one member 2 and the other member 4 into contact with each other via the insert member 6 to form a joined interface (1) where one member 2 and the insert member 6 are in contact and a joined interface (2) where the other member 4 and the insert member 6 are in contact. Move one member 2 and / or the other member 4 to a desired location for forming the joined portion, bring the joined surfaces into contact with each other via the insert member 6, and form the joined interface 10.

[0046] The shapes and sizes of one member 2 and the other member 4 are not particularly limited as long as the effects of the present invention are not impaired, and any member capable of raising the temperature in the vicinity of the joint interface 10 by the sliding of the insert material 6 is acceptable.

[0047] (1-2) Second step In the second step, a joining pressure (1) is applied substantially perpendicular to the joint interface (1), a joining pressure (2) is applied substantially perpendicular to the joint interface (2), the joining pressure (1) and the joining pressure (2) are set to different values, and frictional heat is generated by the sliding of one member 2 and the other member 4 and the insert material 6, the joint interfaces (1) and (2) are heated, and the burrs 8 are discharged from the joint interface substantially parallel and substantially perpendicular to the sliding direction.

[0048] It is preferable that the joining pressure (1) be a value equal to or greater than the yield stress and equal to or less than the tensile strength of the insert material 6 and one member 2 at the temperature (1), and the joining pressure (2) be a value equal to or greater than the yield strength and equal to or less than the tensile strength of the insert material 6 and the other member 4 at the temperature (2). By setting the pressure during solid-phase joining to be equal to or greater than the yield stress of the joined material, the discharge of the burrs 8 from the joint interface 10 is started, and if the pressure is increased between the yield stress and the tensile strength, the discharge of the burrs 8 is accelerated. Similar to the yield stress, since the tensile strength at a specific temperature is also substantially constant depending on the joined material, the joining temperature corresponding to the set pressure can be realized.

[0049] Both members are deformed at the joint interface 6, and new surfaces are formed on the joint surfaces of both members. By bringing these new surfaces into contact with each other, a good joint portion can be obtained. Here, since the temperature dependence of the strength is different between one member 2 and the other member 4, the deformation behavior and the discharge state of the burrs 8 in the vicinity of the joint interface 10 are also different, but as long as new surfaces are formed on the joint interface 10 by the deformation and the discharge of the burrs, it is acceptable.

[0050] (1-3) Third step The third step is to stop the sliding in the second step to form a joint surface. By stopping the sliding after the burrs 8 are discharged from the entire surface of the joint interface 10, a good joined body can be obtained. Note that the joining pressures (1) and (2) applied to each joined material in the second step may be maintained as they are, or may be set to higher values for the purpose of discharging the burrs 8 and bringing the new surfaces into closer contact with each other.

[0051] Here, the timing of stopping the sliding is not limited as long as it is after the burrs 8 are discharged from the entire surface of the joint interface 10. However, at the joint interfaces (1) and (2), it is preferable to set the approach amounts of one member 2 and the other member 4 so that new surfaces are formed over substantially the entire area of these joint interfaces. More preferably, new surfaces are formed over the entire area of the joint interface 10 in both one member 2 and the other member 4. By bringing the new surfaces of one member 2 and the other member 4 into contact with the new surface of the insert material 6, a strong joint portion can be obtained. Here, it is more preferable to stop the increase in the approach amount at the timing when new surfaces are formed over the entire area of the joint interface 10 in both members. By ending the joining process at this timing, a good joint in which the entire area of the joint interface 10 is joined by contact between the new surfaces can be obtained most efficiently. By making the total of the surface area of the discharged burrs 8 and the increased portion of the joint interface 10 increased due to the deformation of the joined materials approximately twice the area of the joint interface 10 before joining, new surfaces can be formed over the entire area of the joint interface 10.

[0052] As described above, the representative embodiments of the present invention have been explained. However, the present invention is not limited to these alone, and various design changes are possible, and all of these design changes are included in the technical scope of the present invention.

Explanation of reference numerals

[0053] 2 ··· One member, 4 ··· The other member, 6 ··· Insert material, 8 ··· Burrs, 10 ··· Joint interface.

Claims

1. A linear friction joining device for joining one member and another member, wherein the one member and the other member are brought into contact via an insert material, and a joining interface (1) where the one member and the insert material are in contact and a joining interface (2) where the other member and the insert material are in contact are formed by a gripping mechanism, a vibration mechanism for relatively vibrating the insert material between the one member and the other member, and a pressing mechanism for applying a joining pressure substantially perpendicular to the joining interface (1) and the joining interface (2), wherein an electric motor is used as a drive source of the vibration mechanism, and the electric motor is an electric servo motor, characterized in that it is a linear friction joining device.

2. Converting the rotational motion of the electric motor into a linear motion using a ball screw or a feed screw, characterized in that it is the linear friction joining device according to Claim 1.

3. Making the amplitude and / or frequency of the vibration by the vibration mechanism variable, characterized in that it is the linear friction joining device according to Claim 1 or 2.

4. Making the amplitude and / or frequency of the vibration by the vibration mechanism fixed, characterized in that it is the linear friction joining device according to Claim 1 or 2.

5. Making the amplitude of the vibration by the vibration mechanism 0.1 to 5 mm and the frequency 10 to 100 Hz, characterized in that it is the linear friction joining device according to any one of Claims 1 to 3.

6. Set the pressing force by the pressing mechanism to 1.5 × 10 ４ kg or less, characterized in that it is the linear friction joining device according to any one of Claims 1 to 3.

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