JP6187247B2 - Joining method that combines press-fitting and brazing - Google Patents

Description

  The present invention relates to a joining method that combines press-fitting and brazing, and more particularly to a joining method that combines press-fitting and brazing in which an inner metal member is press-fitted into an outer metal member and then joined by brazing.

  Conventionally, as a joining method combining press-fitting and brazing in which an inner metal member is press-fitted into an outer metal member and then joined, there is one disclosed in Patent Document 1. This press-fits the press-fitting fitting portion (outer metal member) of the fitting shaft hole of the clutch cone into the fitting shaft portion (inner metal member) of the transmission gear body, and brazes both parts. . When the fitting shaft portion and the press-fitting fitting portion are press-fitted, the space portion sealed by the press-fitting portion and the contact portion between the seat surface of the transmission gear body and the seat surface of the clutch cone is formed between the transmission gear body and the clutch cone. Formed between. And brazing is performed by the brazing material previously set so that it may arrange | position in the said space part. Therefore, brazing is performed in the range of the space portion. That is, a portion sandwiched between a press-fitting portion between the fitting shaft portion and the press-fitting fitting portion and a contact portion between the transmission gear main body and the seat surface of the clutch cone is brazed.

JP 2001-129661 A (see in particular paragraphs 0025, 0027, 0030, 0042 and 0043)

  In the technique disclosed in Patent Document 1, the press-fitted portion between the inner metal member and the outer metal member and the portion (space portion) brazed by the brazing material are different from each other. That is, the press-fitted portion between the inner metal member and the outer metal member is not brazed. Therefore, there exists a problem that a joining component with larger joining strength cannot be obtained.

  The present invention has been made in view of the above-described present situation in a joining method that combines press-fitting and brazing. A joining method that combines press-fitting and brazing can provide a joining component with higher joining strength. For the purpose of provision.

In order to solve the above-mentioned problems, the present invention is a joining method that combines press-fitting and brazing, in which an inner metal member is press-fitted into an outer metal member and then joined by brazing. A brazing material loading step of loading a brazing material into a recess formed on the surface of the press-fitting portion so as not to protrude from the surface; and an inner metal member loaded with the brazing material is inserted into the outer metal member to press-fit the inner metal member A press-fitting process in which a part is press-fitted into a press-fitted part of the outer metal member, and the inner metal member is brazed to the outer metal member by heating the workpiece obtained in the press-fitting process to a melting point or higher of the brazing material And the outer metal of the press-fitted part of the inner metal member is 0.05 to 50 μm, and the surface roughness of the press-fitted part of the outer metal member is 0.05 to 50 μm Member pressure Press-fitting margin to parts is at 10μm or less than 0 .mu.m, in the above brazing process, and the surface roughness of the press-fitted portion of the surface roughness and the outer metal member of the press-fitting portion of the inner metal member is set within the above range As a result, the molten brazing material penetrates and expands between the press-fit portion of the inner metal member and the press-fit portion of the outer metal member by a capillary phenomenon.

  According to the present invention, the brazing material is loaded on the surface of the press-fitted portion of the inner metal member, the press-fitted portion of the inner metal member is press-fitted into the press-fitted portion of the outer metal member, and the obtained workpiece is equal to or higher than the melting point of the brazing material. Therefore, the press-fitted portion between the inner metal member and the outer metal member matches the portion to be brazed with the brazing material, and the press-fitted portion between the inner metal member and the outer metal member is brazed. Is done. Therefore, the bonding strength of the obtained bonded component is further increased.

  As described above, according to the present invention, there is provided a joining method combining press-fitting and brazing, in which a joined part having a greater joining strength can be obtained.

  Moreover, in the present invention, since the surface roughness of the press-fitted portion of the inner metal member and the surface roughness of the pressed-in portion of the outer metal member are 0.05 μm or more, the surface tension of the brazing material is greatly reduced. For this reason, the brazing material becomes wet, and the molten brazing material penetrates sufficiently between the press-fitted portion of the inner metal member and the press-fitted portion of the outer metal member by capillary action. This leads to favorable results for improving the brazing joint strength.

Further, in the present invention, since the surface roughness of the press-fitted portion of the inner metal member and the surface roughness of the press-fitted portion of the outer metal member are 50 μm or less, the brazing material has irregularities on the surface of the press-fitted portion of the inner metal member and The unevenness on the surface of the pressed-in portion of the outer metal member can be overcome sufficiently satisfactorily. Also in this case, the brazing material becomes wet, and the molten brazing material penetrates sufficiently between the press-fitted portion of the inner metal member and the press-fitted portion of the outer metal member.

Furthermore, in the present invention, since the press-fitting allowance of the press-fitted portion of the inner metal member to the press-fitted portion of the outer metal member is 10 μm or less, the press-fitted portion of the inner metal member can be used even when the workpiece is heated in the brazing process. An appropriate gap is secured between the outer metal member and the pressed-in portion, and the gap is prevented from becoming too small. Also in this case, the brazing material becomes wet, and the molten brazing material penetrates sufficiently between the press-fitted portion of the inner metal member and the press-fitted portion of the outer metal member.

  In the present invention, the press-fitting allowance of the press-fitted portion of the inner metal member to the press-fitted portion of the outer metal member may be zero (zero) or more. When the press-fitting allowance is negative (negative value), the relative positions of the inner metal member and the outer metal member are shifted, and the product accuracy is not satisfied.

  In the present invention, it is preferable that the carburizing process of the workpiece is simultaneously performed in the brazing step.

  According to this structure, a workpiece | work can be carburized simultaneously with brazing using the heating of a brazing process. Therefore, the production efficiency is improved.

  In the present invention, in the brazing step, the work obtained in the press-fitting step is put in a heat treatment furnace, the pressure in the heat treatment furnace is reduced to 10 Pa or less, and the work is heated to 900 to 950 ° C. Then, the chain unsaturated hydrocarbon gas is introduced into the heat treatment furnace, the pressure in the heat treatment furnace is reduced to 10 Pa or less, and the introduction and depressurization of the chain unsaturated hydrocarbon gas are repeated a plurality of times. It is preferable to lower the temperature of the workpiece to 830 to 870 ° C.

  According to this configuration, carburizing with less unevenness of carburization can be performed by a so-called vacuum carburizing technique compared to, for example, gas carburizing. Further, by repeating the introduction and decompression of the chain unsaturated hydrocarbon gas a plurality of times, it is possible to reliably carburize fine and narrow portions where the chain unsaturated hydrocarbon gas is difficult to reach.

  In the present invention, the chain unsaturated hydrocarbon gas is preferably acetylene gas.

  According to this configuration, by using acetylene gas as the chain unsaturated hydrocarbon gas, generation of soot can be suppressed as compared with the case where a chain saturated hydrocarbon gas such as propane gas is used. .

  In this invention, it is preferable to provide the hardening process which quenches the temperature-fall workpiece | work after the said brazing process.

  According to this configuration, since the workpiece is quenched after the workpiece is carburized simultaneously with the brazing process, the surface of the workpiece can be hardened by so-called carburizing and quenching, and the surface hardness of the workpiece can be increased.

  In the present invention, the brazing material is preferably a copper-manganese alloy brazing material having a copper content higher than the manganese content.

  According to this configuration, a brazing material having a melting point near 880 ° C. can be obtained. Therefore, this brazing material is in a liquid phase state at a heating temperature of 900 to 950 ° C. in the brazing step, and is in a solid phase state at a temperature immediately before quenching of 830 to 870 ° C. Therefore, by using this brazing material, brazing and carburizing and quenching can be performed sufficiently satisfactorily in parallel under the above conditions, and as a result, a bonded part having excellent resistance and greater bonding strength can be obtained.

  In the present invention, the inner metal member includes a large-diameter portion having a predetermined outer diameter, a medium-diameter portion having an outer diameter smaller than the large-diameter portion, and a small-diameter portion having an outer diameter smaller than the medium-diameter portion. Is a dynamic vibration absorber formed in the order of the medium diameter portion, the small diameter portion, the large diameter portion, the small diameter portion, and the medium diameter portion in the axial direction, and the outer metal member is a large diameter portion of the inner metal member. A through hole having an inner diameter larger than the outer diameter extends in the axial direction, and the inner peripheral surface of the through hole bulges toward the axial center at the axial center of the through hole. The piston pin of the engine, wherein the central portion in the direction is an attachment portion having an inner diameter smaller than the outer diameter of the large-diameter portion and larger than the outer diameter of the medium-diameter portion, and the press-fitting portion of the inner metal member is the inner metal member The press-fitted portion of the outer metal member is the outer metal It is preferably a mounting portion of the timber.

  According to this configuration, the dynamic vibration absorber can be firmly joined to the piston pin of the engine that is used in an environment where heat load and vibration are severe, so that the dynamic vibration absorber can be detached from the piston pin even in such an environment. Is suppressed.

  The present invention provides a joining method that combines press-fitting and brazing to obtain a joined part with higher joint strength. Therefore, the development of a technique for joining by press-fitting an inner metal member into an outer metal member and then joining them.・ Contribute to improvement.

It is a front view of a piston and a connecting rod of an engine for explaining an inner metal member and an outer metal member according to an embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is a process figure of the joining method which combined press fit and brazing based on the embodiment of the present invention. It is a time chart which shows the change of the furnace temperature in the case of performing brazing and vacuum carburizing simultaneously. It is a map for demonstrating the influence with respect to the joint strength of the surface roughness of the press-fit part before press-fit, and the press-fitting allowance. It is a table | surface of the experimental result for demonstrating the effect of this invention.

(1) Explanation of members In the joining method according to this embodiment, which combines press-fitting and brazing, the inner metal member is a dynamic damper for reducing combustion noise of the engine, and the outer metal The member is an engine piston pin.

  Referring to FIGS. 1 and 2, a cavity 1 a is formed on the top surface of the piston 1, and a piston ring 1 b is fitted on the outer peripheral surface of the piston 1. The piston 1 is connected to the small end portion 10 a of the connecting rod 10 via the piston pin 2. A shaft insertion hole 10e is formed in the large end portion 10b of the connecting rod 10, and a crankshaft (not shown) is inserted through the shaft insertion hole 10e. The small end portion 10a and the large end portion 10b of the connecting rod 10 are connected by a connecting portion 10c. The reciprocating motion of the piston 1 is transmitted to the crankshaft via the connecting rod 10, and the crankshaft rotates.

  As shown in FIG. 2, a pin insertion hole 10 d is formed in the small end portion 10 a of the connecting rod 10, and the axial center portion of the piston pin 2 is rotatably inserted through the pin insertion hole 10 d via a bush 11. Yes. Two bosses 1 c are formed to bulge on the back surface of the piston 1 so as to sandwich the small end 10 a of the connecting rod 10. A pin support hole 1d is formed in each of the two bosses 1c, and each end of the piston pin 2 is rotatably inserted into each pin support hole 1d. Each pin support hole 1d is provided with a snap ring 1e for restricting movement of the piston pin 2 in the axial direction.

  The piston pin 2 has a cylindrical shape, and a through hole 2a extends in the axial direction. A central portion in the axial direction of the inner peripheral surface of the through hole 2a bulges toward the axial center side, whereby a large-diameter portion (press-fit portion) 20a of the dynamic vibration absorber 20 is press-fitted (press-fit portion) 2b Has been. The through-hole 2a and the attachment portion 2b each have a circular cross-sectional shape and are arranged concentrically with each other. The material of the piston pin 2 is steel, and specific examples thereof include alloy steel such as SCr420H.

  The dynamic vibration absorber 20 is accommodated in the through hole 2a. As shown in FIG. 2, the dynamic vibration absorber 20 includes a large-diameter portion 20a that is press-fitted into the mounting portion 2b, a pair of medium-diameter portions 20b that extend in the axial direction of the through hole 2a, and the medium-diameter portion 20b. The large-diameter portion 20a has a pair of small-diameter portions 20c that are supported so as to vibrate in the radial direction of the piston pin 2.

  The dynamic vibration absorber 20 is formed in the order of the medium diameter portion 20b, the small diameter portion 20c, the large diameter portion 20a, the small diameter portion 20c, and the medium diameter portion 20b in the axial direction. The large-diameter portion 20a, the medium-diameter portion 20b, and the small-diameter portion 20c each have a circular cross-sectional shape and are arranged concentrically with each other. The pair of medium diameter portions 20b have the same length and diameter, and the pair of small diameter portions 20c have the same length and diameter.

The inner diameter φ _2a of the through hole 2a is larger than the outer diameter φ _20a of the large diameter portion 20a. The inner diameter φ _2b of the attachment portion 2b is smaller than the outer diameter φ _20a of the large diameter portion 20a and larger than the outer diameter φ _20b of the medium diameter portion 20b. The outer diameter φ _20b of the intermediate-diameter portion 20b is smaller than the outer diameter φ _20a of the large-diameter portion 20a. Outer diameter phi _20c of the small diameter portion 20c is smaller than the outside diameter phi _20b of the middle-diameter portion 20b. That is, the relation of φ _2a > φ _20a > φ _2b > φ _20b > φ _20c is set. Here, the outer diameter φ _20a of the large diameter portion 20a is, for example, about 7 to ₂₀ mm.

  The large-diameter portion 20 a of the dynamic vibration absorber 20 is press-fitted into the attachment portion 2 b of the piston pin 2. Thereby, a pair of small diameter part 20c and a pair of medium diameter part 20b of the dynamic vibration damper 20 are arrange | positioned mutually symmetrically on the boundary of the axial direction center part of the through-hole 2a.

  The dynamic vibration absorber 20 is integrally formed of metal. The material of the dynamic vibration absorber 20 is steel, and specific examples thereof include alloy steel such as SCM435.

  Here, the surface roughness (arithmetic average roughness Ra) of the outer peripheral surface of the large-diameter portion 20a of the dynamic vibration absorber 20 and the surface roughness (arithmetic average roughness Ra) of the inner peripheral surface of the mounting portion 2b of the piston pin 2 are described. ) Are each prepared in the range of 0.05 to 100 μm. In addition, the press-fitting allowance (the press-fitting allowance at the radius) of the large-diameter portion 20a to the attachment portion 2b is adjusted within a range of 0 to 20 μm.

  In the spring mass model of the piston 1 and the connecting rod 10, the piston 1, the piston pin 2, and the small end portion 10 a of the connecting rod 10 correspond to a mass point (mass = M (kg)) as a whole, and the small end portion 10 a of the connecting rod 10 The connecting portion 10c that connects the large end portion 10b corresponds to a spring (spring constant = K (N / m)) that supports the mass point with respect to the large end portion 10b. In the combustion stroke, since the piston 1 is pressed with a large force, the piston 1, the piston pin 2, and the small end portion 10a of the connecting rod 10 are integrated with each other with respect to the large end portion 10b of the connecting rod 10 (1 / 2π). ) · (K / M) Resonates at a resonance frequency of 1/2 Hz (stretching resonance of the connecting rod 10). As a result, a peak due to expansion / contraction resonance of the connecting rod 10 is generated in the engine sound, and combustion noise is generated.

  On the other hand, since the dynamic vibration absorber 20 suppresses expansion / contraction resonance of the connecting rod 10 due to the vibration of the middle diameter portion 20b (reducing vibration at the resonance frequency), combustion noise of the engine due to the resonance is reduced. .

(2) Joining method As shown in an enlarged view in FIG. 2, the large-diameter portion 20 a of the dynamic vibration absorber 20 is press-fitted into the mounting portion 2 b of the piston pin 2, and the press-fitted portion is brazed with a brazing material M. ing. Therefore, the dynamic vibration absorber 20 and the piston pin 2 are joined with a greater joining strength. Next, a joining method that combines press-fitting and brazing that can braze the press-fitted portions of the dynamic vibration absorber 20 and the piston pin 2 will be described.

  As shown in FIG. 3, first, the dynamic vibration absorber 20 and the piston pin 2 are degreased and cleaned so that brazing can be performed satisfactorily.

  Next, the brazing material M is loaded into the concave groove 20x formed on the outer peripheral surface of the large-diameter portion 20a of the dynamic vibration absorber 20. In that case, the brazing material M is loaded so as not to protrude outward from the outer peripheral surface of the large diameter portion 20a (a brazing material loading step).

  Next, the dynamic vibration absorber 20 loaded with the brazing material M is inserted into the piston pin 2 and the large-diameter portion 20a of the dynamic vibration absorber 20 is press-fitted into the mounting portion 2b of the piston pin 2 (press-fitting process).

  Next, the obtained workpiece W is heated to the melting point or higher of the brazing material M. Thereby, the brazing filler metal M loaded on the outer peripheral surface of the large-diameter portion 20a is melted to be in a liquid phase state. The brazing material M that has become a liquid phase penetrates into the gap between the large-diameter portion 20a and the attachment portion 2b at the press-fitted portion between the dynamic vibration absorber 20 and the piston pin 2 due to capillary action. Then, by lowering the temperature of the workpiece W below the melting point of the brazing material M, the penetrated brazing material M is solidified and becomes a solid phase. As a result, the dynamic vibration absorber 20 is brazed to the piston pin 2 with the brazing material M at the press-fitted portion between the large diameter portion 20a and the attachment portion 2b (brazing step).

  After that, the penetration rate of the brazing material M (wetting of the brazing material M) is inspected with ultrasonic waves, and only the good workpiece W having a penetration rate larger than a predetermined reference value is subjected to polishing, and the large diameter portion 20a and the attachment portion The brazing material M protruding from the press-fitted portion with 2b is removed. Finally, the entire workpiece W is cleaned.

  Here, in the brazing process, the carburizing process of the workpiece W can be performed simultaneously. FIG. 4 is a time chart showing changes in the furnace temperature when brazing and vacuum carburizing are performed simultaneously in the brazing step. This time chart shows an atmosphere in which the operating pressure is 4 kPa or less, the operating temperature is 800 to 1050 ° C. (maximum 1100 ° C.), the heating method is electric resistance heating, the heater capacity is 87 kW, and the quenching oil amount is 4800 L as a heat treatment furnace. Using a controlled vacuum carburizing furnace, using acetylene gas as the carburizing gas, as the brazing material M, copper-manganese (70% copper content, 30% manganese content, melting point of about 880 ° C.) This is the case where a Cu—Mn) -based alloy brazing material is used.

  In the illustrated example, in the brazing process, first, at a predetermined time when the furnace temperature is maintained at 780 ° C., the workpiece W obtained in the press-fitting process is placed in a heat treatment furnace (reference number a). At this temperature, the brazing material M is not yet melted.

  Next, the pressure in the heat treatment furnace is reduced to 10 Pa or less, for example, 1 Pa. Further, the furnace temperature is raised to 900 to 950 ° C., for example, 930 ° C. That is, the workpiece W is heated to 930 ° C. At this temperature, the brazing filler metal M melts and becomes a liquid phase. The molten brazing material M permeates between the large-diameter portion 20a of the dynamic vibration absorber 20 and the mounting portion 2b of the piston pin 2 by capillary action.

  A predetermined amount of acetylene gas is introduced into the heat treatment furnace in the soaking state at the furnace pressure of 1 Pa and the furnace temperature of 930 ° C. (symbol A). By introducing the acetylene gas, the degree of vacuum in the furnace is temporarily reduced. However, since the atmosphere control type vacuum carburizing furnace automatically reduces the pressure in the furnace to 1 Pa, the degree of vacuum in the furnace is immediately recovered and maintained. Such introduction of acetylene gas and decompression are repeated two more times (symbols C and D). That is, acetylene gas is introduced into the heat treatment furnace three times in total. Thereby, acetylene gas diffuses in the furnace, and the workpiece W is carburized by the vacuum carburizing technique. In addition, the fine and narrow portions of the work W to which acetylene gas is difficult to reach are reliably carburized.

  Next, the temperature in the furnace is lowered to 830 to 870 ° C., for example, 850 ° C. (reference number o). That is, the workpiece W is cooled to 850 ° C. At this temperature, the brazing material M is solidified and becomes a solid phase. Here, the brazing with the brazing material M at the press-fitted portion between the large-diameter portion 20a and the attachment portion 2b is completed, and the brazing process for simultaneously performing the brazing and the carburizing process of the workpiece W is completed.

  In the present embodiment, after the brazing step, the workpiece W that has been cooled to 850 ° C. and is in a soaked state is quenched (quenched) (quenching process, code number). Here, the carburizing and quenching of the workpiece W is completed. The temperature after quenching is 230 ° C., for example. Further, after quenching, the workpiece W is further tempered (slowly cooled). The temperature after tempering is room temperature, for example.

(3) Experimental Example FIG. 5 shows brazing of the surface roughness of the press-fitted portion before press-fitting (that is, the surface roughness of the large diameter portion 20a of the dynamic vibration absorber 20 and the surface roughness of the mounting portion 2b of the piston pin 2). It is a map for demonstrating the influence with respect to joining strength and the influence with respect to the joining strength of the brazing of the press fit allowance to the said attaching part 2b of the said large diameter part 20a. The surface roughness is an arithmetic average roughness Ra (μm). Moreover, it is not the surface roughness of either one of the large diameter part 20a and the attachment part 2b, but the surface roughness of both. The press-fitting allowance is a press-fitting allowance at the radius of the large-diameter portion 20a. It is not a press fit in diameter.

The outer diameter phi _20a of the large-diameter portion 20a and 14 mm, point (i) ~ shown in FIG. 5 (v) and (a) ~ (d) is to achieve, to produce a dynamic vibration absorber 20 and the piston pin 2 . Then, the dynamic vibration absorber 20 and the piston pin 2 are joined by the joining method described with reference to FIGS. 3 and 4, and the obtained workpiece is wetted with the brazing material (penetration rate of the brazing material) and the center accuracy. And the unloading load were evaluated. Furthermore, these evaluations were integrated to finally make a pass / fail judgment. The results are shown in FIG.

  The wetness of the brazing material is inspected with ultrasonic waves, and the percentage of the brazing material penetrating into the contact area between the large diameter portion 20a and the mounting portion 2b (penetration rate) is examined. "Large", 50% or more and less than 90% was "Medium", and less than 50% was "Small". The center accuracy is measured with a three-dimensional measuring instrument to determine how much the axial center of the joined dynamic vibration absorber 20 is displaced from the axial center of the piston pin 2 in the radial direction. The thing over 20 micrometers was made into "defect." The extraction load was measured by pulling the bonded dynamic vibration absorber 20 and the piston pin 2 in the opposite directions in the axial direction, and measuring the load (ton) when the dynamic vibration absorber 20 was removed from the piston pin 2. In the final pass / fail judgment, emphasis was placed on the evaluation of the center accuracy and the extraction load, and the evaluation of the wetting of the brazing material was set to a reference level.

  As apparent from FIG. 6, the points (i) to (v) in which the surface roughness is in the range of 0.05 to 100 μm and the press-fitting allowance is in the range of 0 to 20 μm have good quality determination. (Examples 1 to 5). On the other hand, the points (a) and (b) where the surface roughness is not in the range of 0.05 to 100 μm and the points (c) and (d) where the press-fitting allowance is not in the range of 0 to 20 μm Was poor (Comparative Examples 1 to 4). The reason is considered as follows.

  When the surface roughness is less than 0.05 μm, the outer peripheral surface of the large diameter portion 20a and the inner peripheral surface of the attachment portion 2b are close to a mirror surface. As a result, the surface tension of the brazing material tends to be difficult to decrease, the wetting of the brazing material decreases, and the bonding strength decreases. In addition, the anchor effect tends to be difficult to obtain, and the joint strength also decreases. These lead to a reduction in the punching load.

  When the surface roughness is 0.05 μm or more, the outer peripheral surface of the large-diameter portion 20a and the inner peripheral surface of the attachment portion 2b are ground glass. As a result, the surface tension of the brazing material tends to decrease, the wetting of the brazing material increases, and the bonding strength increases. In addition, the anchor effect tends to be easily obtained, and the joint strength is also increased. These lead to an increase in the punching load.

  When the surface roughness exceeds 100 μm, the molten brazing material tends to hardly get over the irregularities on the outer peripheral surface of the large-diameter portion 20a and the inner peripheral surface of the mounting portion 2b, so that wetting of the brazing material is reduced and the bonding strength Decreases.

  When the press-fitting allowance exceeds 20 μm, the gap between the large-diameter portion 20a and the attachment portion 2b becomes too small during heating of the workpiece W in the brazing process, so that wetting of the brazing material is reduced and bonding strength is increased. Decreases.

  When the press-fitting allowance is less than 0 μm (minus), the relative position between the dynamic vibration absorber 20 and the piston pin 2 is shifted when the work W is heated in the brazing process, and the product accuracy is not satisfied. This leads to a decrease in center accuracy.

  As described above, Examples 1 to 5 satisfying all the preferable ranges of the surface roughness and the press-fit allowance were satisfactory, whereas the preferred ranges of the press-fit allowance were satisfied even if the preferable ranges of the press allowance were satisfied. The comparative examples 1 and 2 and the comparative examples 3 and 4 that do not satisfy the preferable range of the press-fitting allowance even if the preferable range of the surface roughness is satisfied are considered to be poor.

  In addition, it can be seen from FIG. 6 that in Examples 2 and 3 and Comparative Example 4 where the wetting of the brazing material is “large”, the extraction load is significantly larger than the others. Moreover, it turns out that the center precision is not good in the comparative example 3 whose press-fitting allowance is excessively large. This is presumably because the pressure input becomes too large at the time of press-fitting, the dynamic vibration absorber 20 is buckled, and the dynamic vibration absorber 20 and the piston pin 2 are displaced from each other.

(4) Operation, etc. In the present embodiment, a large diameter portion 20a having a predetermined outer diameter, a medium diameter portion 20b having an outer diameter smaller than the large diameter portion 20a, and a small diameter portion having an outer diameter smaller than the medium diameter portion 20b. 20c is the outer diameter of the large-diameter portion 20a. The dynamic vibration absorber 20 is formed by arranging the medium-diameter portion 20b, the small-diameter portion 20c, the large-diameter portion 20a, the small-diameter portion 20c, and the medium-diameter portion 20b in this order. A through-hole 2a having a larger inner diameter is formed extending in the axial direction, and the inner peripheral surface of the through-hole 2a bulges toward the axial center at the axial center of the through-hole 2a. After being press-fitted into the piston pin 2 of the engine, which is an attachment portion 2b having a central portion smaller than the outer diameter of the large-diameter portion 20a and larger than the outer diameter of the medium-diameter portion 20b, and then joined by brazing. For joining methods that combine press-fitting and brazing Therefore, the following characteristic configuration was adopted.

  That is, a brazing material loading step of loading the brazing material M into the concave groove 20x formed on the outer circumferential surface of the large diameter portion 20a of the dynamic vibration absorber 20 so as not to protrude from the outer circumferential surface of the large diameter portion 20a, and loading the brazing material M The dynamic vibration absorber 20 is inserted into the piston pin 2 and the large diameter portion 20a of the dynamic vibration absorber 20 is press-fitted into the mounting portion 2b of the piston pin 2, and the workpiece W obtained in the press-fitting step is inserted into the brazing material M. A brazing step of brazing the dynamic vibration absorber 20 to the piston pin 2 by heating to above the melting point.

  According to this configuration, the press-fitted portion between the dynamic vibration absorber 20 and the piston pin 2 and the portion to be brazed by the brazing material M coincide, and the press-fitted portion between the dynamic vibration absorber 20 and the piston pin 2 is brazed. The Therefore, the joining strength (pull load) of the obtained joining component is further increased.

  Therefore, since the dynamic vibration absorber 20 can be firmly joined to the piston pin 2 which is an operating part used in an environment where heat load and vibration are severe, the dynamic vibration absorber 20 is separated from the piston pin 2 even in such an environment. It is suppressed from coming off.

  Moreover, the surface roughness of the outer peripheral surface of the large-diameter portion 20a of the dynamic vibration absorber 20 and the surface roughness of the inner peripheral surface of the mounting portion 2b of the piston pin 2 are adjusted to 0.05 to 100 μm, and the large-diameter portion 20a is attached. Since the allowance for press-fitting into the part 2b is adjusted to 0 to 20 μm, the brazing material M becomes better wetted for the reasons described above, and the molten brazing material M is interposed between the large-diameter part 20a and the attachment part 2b by capillary action. It penetrates sufficiently well and increases the brazing joint strength (pull-out load). Moreover, the shift | offset | difference (decrease in center precision) of the relative position of the dynamic vibration absorber 20 and the piston pin 2 is suppressed. Furthermore, since the press-fitting allowance is adjusted to 20 μm or less, a problem that the pressure input becomes too large at the time of press-fitting and the small-diameter portion 20c of the dynamic vibration absorber 20 is buckled is suppressed.

  In the present embodiment, the carburizing process of the workpiece W is simultaneously performed in the brazing process.

  According to this structure, the workpiece | work W can be carburized simultaneously with brazing using the heating of a brazing process. Therefore, the production efficiency is improved.

  In this embodiment, in the brazing step, the workpiece W obtained in the press-fitting step is put into a heat treatment furnace, the pressure in the heat treatment furnace is reduced to 10 Pa or less, and the workpiece W is heated to 900 to 950 ° C., In this state, the chain unsaturated hydrocarbon gas is introduced into the heat treatment furnace, the pressure in the heat treatment furnace is reduced to 10 Pa or less, and the introduction and decompression of the chain unsaturated hydrocarbon gas are performed a plurality of times (total 3 The temperature of the workpiece W is lowered to 830 to 870 ° C.

  According to this configuration, carburizing with less unevenness of carburization can be performed by a so-called vacuum carburizing technique compared to, for example, gas carburizing. Further, by repeating the introduction and decompression of the chain unsaturated hydrocarbon gas a plurality of times, it is possible to reliably carburize fine and narrow portions where the chain unsaturated hydrocarbon gas is difficult to reach.

  In the present embodiment, the chain unsaturated hydrocarbon gas is acetylene gas.

  According to this configuration, by using acetylene gas as the chain unsaturated hydrocarbon gas, generation of soot can be suppressed as compared with the case where a chain saturated hydrocarbon gas such as propane gas is used. .

  In the present embodiment, after the brazing step, a quenching process for quenching the workpiece W that has been cooled is provided.

  According to this configuration, since the workpiece W is quenched after the workpiece W is carburized simultaneously with the brazing process, the surface of the workpiece W is hardened by so-called carburizing and quenching, and the surface hardness of the workpiece W is increased. Can do.

  In the present embodiment, the brazing material M is a copper-manganese alloy brazing material having a copper content higher than the manganese content.

  According to this configuration, a brazing material M having a melting point near 880 ° C. is obtained. Therefore, the brazing material M is in a liquid phase state at a heating temperature of 900 to 950 ° C. in the brazing step, and is in a solid state at a temperature immediately before quenching of 830 to 870 ° C. Therefore, by using this brazing material M, brazing and carburizing and quenching can be performed in a sufficiently satisfactory manner under the above conditions, and as a result, a joined part having excellent durability and greater joining strength (pull load). Is obtained.

  By the way, the stress of three-point bending continues to be applied to the piston pin 2 according to the present embodiment during operation. That is, the central portion of the piston pin 2 in the axial direction is inserted into and supported by the pin insertion hole 10 d of the small end portion 10 a of the connecting rod 10. On the other hand, both ends of the piston pin 2 are inserted into and supported by the pin support holes 1d of the boss 1c of the piston 1. Therefore, distortion / deflection continues to occur in the attachment portion 2b of the dynamic vibration absorber 20 located at the axial center of the piston pin 2. Therefore, the dynamic vibration absorber 20 may come off due to fatigue of the attachment portion 2b. Therefore, since a three-point bending load is applied to the piston pin 2, it is preferable to improve the surface hardness in order to increase the fatigue strength of the piston pin 2. Therefore, in this embodiment, the surface of the piston pin 2 is hardened by performing brazing and carburizing quenching in parallel.

  In addition, as shown in FIG. 2 in an enlarged manner, in the dynamic vibration absorber 20, since the joint (see the broken line circle X) between the large diameter portion 20 a and the small diameter portion 20 c is easily broken, it is necessary to increase the strength of this portion X. is there. Therefore, in this embodiment, the surface of the dynamic vibration absorber 20 is also hardened by performing brazing and carburizing quenching in parallel. However, since the portion X is in the back of a narrow space between the through hole 2a of the piston pin 2 and the middle diameter portion 20b of the dynamic vibration absorber 20, the carburizing gas is difficult to reach. Therefore, in the present embodiment, the introduction of the carburizing gas into the heat treatment furnace and the pressure reduction in the heat treatment furnace are performed a plurality of times (3 times in total). Thereby, the said part X to which carburizing gas cannot reach can be carburized reliably, and the target intensity | strength can be expressed in the said part X.

  Further, as shown in an enlarged view in FIG. 2, the corner of the outer peripheral edge of the large-diameter portion 20a of the dynamic vibration absorber 20 is a taper surface, and between this taper surface and the inner peripheral surface of the mounting portion 2b of the piston pin 2 The brazing reservoir Y is formed so that the molten brazing filler metal M accumulates in the space. When the molten brazing material M flows into the small-diameter portion 20c and the medium-diameter portion 20b of the dynamic vibration absorber 20 and hardens, the dynamic vibration absorber 20 characteristics change, and the function of suppressing the expansion and contraction resonance of the connecting rod 10 decreases. Therefore, in the present embodiment, the brazing material Y prevents the brazing material M from flowing into the dynamic vibration absorber 20.

  In the above embodiment, the inner metal member is a dynamic vibration absorber and the outer metal member is a piston pin. However, the inner metal member is not limited to this as long as the inner metal member is press-fitted into the outer metal member and then joined by brazing.

  Moreover, it is needless to say that the various numerical values given in the above embodiment are merely examples, and are not limited thereto.

2 Piston pin (outer metal member)
2a Through-hole 2b Mounting part (press-fit part)
20 Dynamic vibration absorber (inner metal member)
20a Large diameter part (press-fit part)
20b Medium diameter part 20c Small diameter part 20x Concave groove (concave part)
M Brazing material W Workpiece

Claims (7)

The inner metal member is press-fitted into the outer metal member and then joined by brazing, which is a joining method that combines press-fitting and brazing,
A brazing material loading step of loading a brazing material so as not to protrude from the surface into a recess formed on the surface of the press-fitting portion of the inner metal member;
A press-fitting step of inserting the inner metal member loaded with the brazing material into the outer metal member and press-fitting the press-fitted portion of the inner metal member into the press-fitted portion of the outer metal member;
A brazing step of brazing the inner metal member to the outer metal member by heating the workpiece obtained in the press-fitting step to a melting point or higher of the brazing material,
The surface roughness of the press-fitting part of the inner metal member and the surface roughness of the press-fitted part of the outer metal member are 0.05 to 50 μm,
The press-fitting allowance of the press-fitted portion of the inner metal member to the press-fitted portion of the outer metal member is 0 μm or more and 10 μm or less,
In the brazing step, due to setting the surface roughness of the press-fitted portion of the inner metal member and the surface roughness of the press-fitted portion of the outer metal member within the above range, the molten brazing material is Between the press-fitted portion of the inner metal member and the press-fitted portion of the outer metal member, infiltrate and expand by capillary action,
A joining method that combines press-fitting and brazing. In the joining method combining the press-fitting and brazing according to claim 1,
In the brazing process, the carburizing process of the workpiece is performed at the same time.
A joining method that combines press-fitting and brazing. In the joining method combining the press-fitting and brazing according to claim 2,
In the above brazing process,
The work obtained in the press-fitting step is put in a heat treatment furnace, the pressure in the heat treatment furnace is reduced to 10 Pa or less, the work is heated to 900 to 950 ° C., and in this state, the chain unsaturated hydrocarbon gas is heat treated. Introducing into the furnace, reducing the pressure in the heat treatment furnace to 10 Pa or less, repeating the introduction and decompression of this chain unsaturated hydrocarbon gas a plurality of times, and then lowering the temperature of the work to 830-870 ° C.,
A joining method that combines press-fitting and brazing. In the joining method combining press-fitting and brazing according to claim 3,
The chain unsaturated hydrocarbon gas is acetylene gas,
A joining method that combines press-fitting and brazing. In the joining method combining press-fit and brazing according to claim 3 or 4,
After the brazing step, it includes a quenching process for quenching the cooled workpiece.
A joining method that combines press-fitting and brazing. In the joining method which combined press-fit and brazing according to any one of claims 1 to 5,
The brazing material is a copper-manganese alloy brazing material in which the copper content is higher than the manganese content.
A joining method that combines press-fitting and brazing. In the joining method which combined press-fit and brazing according to any one of claims 1 to 6,
The inner metal member includes a large-diameter portion having a predetermined outer diameter, a medium-diameter portion having an outer diameter smaller than the large-diameter portion, and a small-diameter portion having an outer diameter smaller than the medium-diameter portion. It is a dynamic vibration absorber formed in the order of the diameter part, the small diameter part, the large diameter part, the small diameter part, and the medium diameter part,
The outer metal member is formed such that a through-hole having an inner diameter larger than the outer diameter of the large-diameter portion of the inner metal member extends in the axial direction, and an inner peripheral surface of the through-hole in an axial central portion of the through-hole. The piston pin of the engine is an attachment part having an inner diameter that is smaller than the outer diameter of the large diameter part and larger than the outer diameter of the medium diameter part. Yes,
The press-fitted portion of the inner metal member is a large diameter portion of the inner metal member,
The pressed-in portion of the outer metal member is an attachment portion of the outer metal member.
A joining method that combines press-fitting and brazing.

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