JP2001287052A - Joint and method for friction pressure welding of tubular member made of carbon steel and solid round bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint of a tubular member and a solid round bar made of carbon steel which can withstand a heavy load and to provide a friction pressure welding method by which this joint can be realized. SOLUTION: When welding the tip member 3 of a rod which is the solid round bar made of the carbon steel whose outer diameter is almost the same as that of a rod main body 2 to the end face of the rod main body 2 which is a tubular member made of carbon steel, the friction pressure welding is performed by a friction pressure and an upset pressure lower than standard conditions. Consequently, a burr 7 having a rise part 8 and a notch part 9 is formed, and the burr 7 is formed which has following dimensions: the radius of curvature of a starting end part 8a of the rise part 8 is almost 1 mm or above and the distance L between a sharp-pointed angle apex 9a in the notch part 9 and a virtual surface S obtained by connecting the surfaces 2a, 3a of materials 2, 3 to be subjected to pressure welding is almost 0.5 mm or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint suitably applied to a cylinder rod or the like formed by joining a rod end member to one end surface of a rod body as a tubular member and joining a rod end member to the other end surface. About
The present invention also relates to a method for friction welding a carbon steel tubular member and a solid round bar, which is preferably used when manufacturing the cylinder rod.

[0002]

2. Description of the Related Art Hydraulic cylinders are often used as actuators in construction machines such as hydraulic shovels. However, from the viewpoint of reducing manufacturing costs, the hydraulic cylinders can be reduced in weight without deteriorating mechanical properties. There is a strong demand for this. The most effective measure against this demand for weight reduction is to reduce the weight of the cylinder rod.

As shown in FIG. 8, a conventional cylinder rod 21 has a rod end member 23 integrally formed with a rod body portion 22 and a rod end portion 23 which are solid round bars. 25 are joined. Therefore, by making the rod body portion 22 which is a solid material a hollow material, it is possible to reduce the weight by reducing the material and also reduce the manufacturing cost. Therefore, as shown in FIG. 2, a hollow cylindrical tubular member is used as a rod body 2, and a rod end member 3 and a rod end member 4 are joined to both end surfaces of the rod body 2, respectively.
Is being used.

[0004] Incidentally, as a joining method of the rod body 2, the rod tip member 3 and the rod end member 4, arc welding, electron beam welding, friction welding, or the like is used. Among these, friction welding tends to be frequently used because it has advantages such as less joining defects and faster joining speed than the welding method.

[0005] As a material of the cylinder rod 1, carbon steel is generally used. Standard friction welding conditions for carbon steel are defined in JIS (Japanese Industrial Standards). The friction welding conditions shown in Tables 1 and 2 below are based on JIS Z36.
This is an excerpt from 2007.

[0006]

[Table 1]

[0007]

[Table 2]

[0008] Type 1 of the joint type in Table 1 and Table 2
9A is a type in which solid round bars having the same outer diameter are pressed against each other as shown in FIG. 9A, and type 2 has both an outer diameter and an inner diameter as shown in FIG. 9B. Tubular member of same diameter (hollow material)
This is a type in which they are pressed against each other, and type 3 is as shown in FIG.
As shown in (1), a tubular member having the same outer diameter is pressed against a solid round bar. In addition, type 4 is a type in which solid round bars having different outer diameters or solid round bars and a plate material are pressed against each other as shown in FIG. As shown in e), a tubular member having an outer diameter different from that of a solid round bar or a tubular member and a plate material are pressed against each other.

In the rod end member 3 and the rod end member 4 of the above-described cylinder rod 1, the joint-side ends 3c, 4c are both formed in a cylindrical shape, and the joint-side ends 3c, 4c are provided on the outer peripheral side. A flange is formed over the entire circumference, and the flange and the rod body 2 are joined. Therefore, the type of joint between the rod body 2 and the rod end member 3 and the rod end member 4 is as follows.
If attention is paid only to the vicinity, it can be considered to correspond to type 2, but considering the heat capacity of the entire member, type 3 is considered to be the closest. Then, the carbon content C of the base material is 0.38 to 0.42%, and the outer diameter D of the bonding surface of the base material is 70 to 8%.
In the case of 5 mm, the standard conditions are, based on Tables 1 and 2, a peripheral speed of 2 to 10 m / sec, a friction pressure of 80 MPa, an upset pressure of 140 MPa, a friction allowance of 5 to 7 mm, and a total allowance of 12 to 14 mm. In addition, peripheral speed 2-10m / s
ec is about 480 when the outer diameter D of the joining surface is 80 mm.
２2400 rpm.

FIG. 10 is a time chart showing a pressure welding cycle when friction welding is performed based on standard conditions. Here, the rotation speed N of the material to be pressed N = 700 rpm, the friction pressure P1 = 80 MPa, and the upset pressure P2 = 140 MPa.
a, friction allowance Wr = 5 mm, total allowance W = 13 mm, friction time Tr = 8 sec, upset time Ta = 8
Friction welding was performed in sec.

FIG. 11 is a partially enlarged cross-sectional view showing the shape of the burr 26 formed on the press-contact portion 5 when friction press-contact is performed according to the press-contact cycle of FIG. As a result of inspecting the press-contact portion 5 by ultrasonic flaw detection, no defective bonding was recognized at all, and it was confirmed that the bonding was good.

[0012]

However, when a high load required for a hydraulic cylinder for a construction machine is applied to the press-contact portion 5, the burrs 26 cause the outer peripheral surfaces 2a, 3a of the press-contact members 2, 3 to be pressed. Fatigue fracture occurred due to stress concentration on the starting end portion 27a of the rising portion 27 rising from the bottom. Further, depending on the shape of the burr 26, there is a possibility that fatigue breakdown may occur due to stress concentration at the substantially V-shaped notch portion 28 generated substantially at the center of the press contact portion 5.

In a process after the friction welding process, a burr 26 is formed.
Can be avoided, but the cylinder rod 1 presses the rod end member 3 and the rod end member 4, which are solid members, to both end surfaces of the rod body 2, which is a tubular member. Therefore, it is impossible to remove the burr 26 generated on at least one inner diameter side surface.

[0014] Since the pressure contact portion 5 at the time of friction welding is limited in strength, the above-mentioned hollow member (tubular member) is used in a hydraulic cylinder to which a high load is applied, such as for construction machinery. At present, it is difficult to apply the cylinder rod 1 that has been used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has as its object to provide a joint between a carbon steel tubular member and a solid round bar which can withstand a high load. Another object of the present invention is to provide a method of friction welding a carbon steel tubular member and a solid round bar, which can realize the above joint.

[0016]

Means and Effects for Solving the Problems Claim 1
Is a joint formed by friction-welding an end face of a tubular member 2 made of carbon steel to a solid round bar 3 made of carbon steel having an outer diameter substantially the same as that of the tubular member 2 described above. The burr 7 has a rising portion 8 rising from the surfaces 2a, 3a of the materials to be pressed 2, 3 and a substantially V-shaped notch portion 9 formed substantially at the center of the pressing portion 5, and a starting end of the rising portion 8 The radius of curvature R of the portion 8a is approximately 1 mm or more, and the apex 9a of the notch 9 and the surface 2a of the pressure-contact members 2, 3;
The distance L from the virtual plane S connecting the 3a to each other is approximately 0.5 mm
It is characterized by the above.

In the joint according to the first aspect, the burr 7 is shaped so that stress is not excessively concentrated, so that fatigue strength can be improved. As a result, a joint that can withstand a high load can be realized.

The cylinder rod according to a second aspect of the present invention is formed by frictionally pressing a rod tip member 3 on one end surface of a rod body 2 which is a tubular member made of carbon steel, and frictionally pressing a rod end member 4 on the other end surface. In the cylinder rod 1, at least one of a joint between the rod body 2 and the rod tip member 3 and a joint between the rod body 2 and the rod end member 4 is the joint according to claim 1.

According to the cylinder rod 1 of the second aspect, the fatigue strength of the joint can be improved as described above. Thereby, the cylinder rod 1 that can withstand a high load can be realized. Therefore, by applying the cylinder rod 1 of the present invention to a hydraulic cylinder for construction equipment, it is possible to reduce the weight without deteriorating the mechanical properties of the hydraulic cylinder, and to reduce the manufacturing cost by reducing the material. It becomes possible.

Further, in the method of friction welding a tubular member made of carbon steel and a solid round bar according to a third aspect of the present invention, an end face of the tubular member 2 made of carbon steel is provided on the end surface of the tubular member 2 having substantially the same outer diameter as the tubular member 2. When the solid round bar 3 made by welding is friction-welded, the standard rotation speed,
In the upset process, the materials to be pressed 2 and 3 are contacted and rotated at a friction pressure lower than the standard friction pressure and the standard friction shift allowance, and in the upset process, the upset pressure lower than the standard upset pressure and the standard upset shift allowance. It is characterized by upsetting.

According to a fourth aspect of the present invention, in the method for friction welding a tubular member made of carbon steel and a solid round bar, the friction pressure is about 30 to 50% of the standard friction pressure, and the upset pressure is the friction pressure. It is characterized by being about twice the pressure.

In the friction welding method of claim 3 and claim 4, the friction pressure is lower than the standard friction pressure, and the upset pressure is lower than the standard upset pressure. Because of the lowering, the burrs 7 are formed more slowly than in the case of the standard pressure. Thus, the press-contact portion 5 having the burr shape described in claim 1 can be realized. This is because the burr 7 is formed slowly, and it is considered that the tip side of the burr 7 can be suppressed from falling down toward the outer peripheral surfaces of the pressure-contact members 2 and 3.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of a joint and a friction welding method for a carbon steel tubular member and a solid round bar according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partially enlarged cross-sectional view of a press contact portion according to the present invention,
FIG. 2 is a schematic view of a cylinder rod 1 to which the present invention is applied.

The cylinder rod 1 is, as shown in FIG.
A tubular member which is a hollow member is defined as a rod body 2, and a rod end member 3 and a rod end member 4 are provided on both end surfaces of the rod body 2.
Are friction-welded to each other. The rod tip member 3 and the rod end member 4 are both joined side ends 3c, 4c.
Since c is formed in a columnar shape, friction welding can be treated as a solid round bar. Joining end 3c, 4
The outer diameter of c is substantially the same as the outer diameter of the rod body 2. The rod body 2, the rod tip member 3, and the rod end member 4
Each of them is formed of carbon steel having a carbon content C of about 0.38 to 0.42%. The rod body 2 has an outer diameter of 70
８５85 mm, and the wall thickness is about 12.5-18 mm. Therefore, the joint surface outer diameter D is equal to the outer diameter of the rod body 2 and is 70 to 85 mm.

FIG. 1 shows a rod body 2 and a rod tip member 3.
FIG. 3 is an enlarged cross-sectional view showing a shape of an outer peripheral side of a press contact portion 5 of the first embodiment, and an outer peripheral shape of a press contact portion 6 between the rod body 2 and the rod end member 4 is the same as that of FIG.

The burr 7 generated on the outer peripheral side of the press contact portion 5 includes a rising portion 8 rising from the outer peripheral surfaces 2a, 3a of the press contact members 2, 3, and a substantially V-shaped notch formed substantially in the center of the press contact portion 5. A part 9. The radius of curvature R of the start end portion 8a in the rising portion 8 is approximately 1 mm or more, and the distance L between the cusp 9a and the virtual plane S in the notch portion 9 is approximately 0.5 mm or more. The virtual plane S is a plane that connects the outer peripheral surfaces 2a and 3a of the materials to be pressed 2 and 3 with each other.

As shown in FIG. 3, a flange 10 is formed over the entire outer peripheral side at the joint side end 3c of the rod tip member 3 which is a solid material. The thickness of the flange 10 is substantially the same as the thickness of the rod body 2. And
A region W between the joining-side end 3c and a plane CS including the joining surface (the end surface of the flange 10) has a loose portion (12 mm to 15 m).
m), and since the inner peripheral surface 10b of the flange 10 and the inner peripheral surface 2b of the rod body 2 substantially coincide with each other, the shape of the inner peripheral burr 7 is the same as that of the outer peripheral burr 7 shown in FIG. They are almost the same. In addition, the shape of the burr on the inner peripheral side in the press contact portion 6 between the rod body 2 and the rod end member 4 is the same as that in FIG. Therefore, the analysis result of the burr 7 described below applies to both the outer peripheral side and the inner peripheral side. In FIG. 3, the burrs 7 on the outer peripheral side are omitted.

By the way, in the cylinder rod 1 using the tubular member (rod body 2) which is a hollow material, the cross-sectional dimensions are determined by the buckling strength according to the maximum load condition. This is because the buckling limit stress is sufficiently larger than the fatigue limit stress. In the cylinder rod 1 designed in this manner, the base material stress of the rod body 2 is １ ／ to １ ／ or less of the fatigue limit stress. Therefore, if the stress coefficient at the stress concentration portion is 2 or less, the stress at the stress concentration portion can also be set to a stress equal to or less than the fatigue limit stress.

Therefore, in order to quantify the critical shape of the burr 7 such that the stress concentration coefficient is 2 or less, the radius of curvature R of the starting end portion 8a in the rising portion 8, the apex 9a in the notch portion 9, and the virtual plane Regarding the distance L to S, the influence of these on the stress concentration was examined by stress analysis using a computer. The results are shown in FIGS.

FIG. 4 is a graph showing the result of numerical analysis of the effect of the radius of curvature R on the stress concentration coefficient. Note that the distance L
Was set to 2.0 mm. According to FIG. 4, it is understood that the stress concentration coefficient can be set to 2 or less when the radius of curvature R is approximately 1 mm or more.

FIG. 5 is a graph showing the results of numerical analysis of the effect of the distance L on the stress concentration coefficient. The radius of curvature R
Was set to 1.0 mm. According to FIG. 5, it can be seen that when the distance L is about 0.5 mm or more, the stress concentration coefficient can be made 2 or less.

Based on the above analysis results, by performing friction welding so that the radius of curvature R is 1 mm or more and the distance L is 0.5 mm or more, the fatigue strength of the joint can be improved. Further, if this joint is applied to the cylinder rod 1, it is possible to design it to have a fatigue limit stress or less.

In the friction welding method, the materials to be pressed are rotated while being brought into contact with each other at a constant pressure, thereby increasing the temperature of the pressed portion and softening the pressed portion. The method is divided into an upset process in which materials are pressed against each other with a constant pressure to generate burrs in a press-contact portion and to join new surfaces together.

Here, as a friction welding method in which the starting end portion 8a of the rising portion 8 of the burr 7 draws a gentle curve,
A method for reducing the friction pressure P1 is known. This is thought to be because the burr 7 is formed slowly by reducing the friction pressure P1, and it is possible to suppress the tip side of the burr 7 from falling down toward the outer peripheral surfaces 2a, 3a of the pressure-contact members 2, 3. Because it can be done. FIG. 6 is a graph showing the relationship between the friction pressure P1 and the radius of curvature R of the start end portion 8a of the rising portion 8. In addition, the upset pressure P2 was set to twice the friction pressure P1, and other conditions were set to standard conditions defined by JIS. According to FIG. 6, if the friction pressure P1 is approximately 50 MPa or less, the radius of curvature R is set to 1.
It can be seen that it can be made 0 mm or more. Preferably, the pressure may be set to about 30 to 50% of the standard friction pressure.

FIG. 7 is a time chart showing a pressure welding cycle when friction welding is performed according to the present invention. In the present embodiment, as described above, the carbon content C of the material to be pressed is set to 0.1.
38 to 0.42%, the outer diameter D of the joining surface of the material to be pressed is 70 to 8
In the case of 5 mm, the friction welding condition is set as the rotation speed N = 700.
rpm, friction pressure P1 = 30 MPa, upset pressure P
2 = 60MPa, Friction side allowance Wr = 5mm, All side allowance W
= 13 mm and friction welding was performed. Here, in the friction welding, in order to obtain a sound joining, the frictional allowance Wr is required.
It is important to manage. In the present embodiment, since the friction pressure P1 is smaller than the standard condition, the friction time Tr needs to be increased in order to obtain the same friction deviation as the standard condition. Therefore, the friction time Tr under the standard condition is 8
Seconds, the friction time Tr in the present embodiment is 50 seconds. The upset time Ta is 8 seconds as in the case of the standard condition.

As described above, according to the present embodiment, since the shape of the burr 7 is such that stress is not excessively concentrated, the fatigue strength of the press contact portions 5 and 6 can be improved. As a result, a joint that can withstand a high load can be realized.

The above joint is applied to a cylinder rod 1 in which a rod end member 3 and a rod end member 4 which are solid members are friction-welded to both end surfaces of a rod body 2 which is a hollow member. A cylinder rod 1 that can withstand a load can be realized. Therefore, by applying the cylinder rod 1 to a hydraulic cylinder for construction machinery, it is possible to reduce the weight without deteriorating the mechanical properties of the hydraulic cylinder, and it is possible to reduce the manufacturing cost by reducing the material. .

In the case where the rod tip member 3 and the rod end member 4 are friction-welded to the rod body 2 at the same time when the cylinder rod 1 is manufactured, the joints and friction-welding of the present invention are applied to both the pressure-contact portions 5 and 6 respectively. The method needs to be applied.
This is because the burrs on the inner peripheral side cannot be removed after the friction welding. On the other hand, when the rod tip member 3 and the rod end member 4 are friction-welded to the rod body 2 one by one, it is necessary to apply the joint and the friction welding method of the present invention to at least the pressure-welded portion to be friction-welded later. This is because the burrs on the inner peripheral side can be removed from the press-contact portion that has been friction-welded first.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of an outer peripheral side of a press contact portion according to the present invention.

FIG. 2 is a schematic view of a cylinder rod to which the present invention is applied.

FIG. 3 is a partially enlarged sectional view of an inner peripheral side of the press contact portion.

FIG. 4 is a graph showing a result of a numerical analysis of an influence of a radius of curvature of a start end portion at a rising portion of a burr on a stress concentration coefficient.

FIG. 5 is a graph showing a numerical analysis result of an influence of a distance between a vertex at a notch portion of a burr and an imaginary plane connecting surfaces of a material to be pressed on a stress concentration coefficient.

FIG. 6 is a graph showing a relationship between friction pressure and the radius of curvature.

FIG. 7 is a time chart showing a pressure welding cycle when friction welding is performed based on the present invention.

FIG. 8 is a schematic view of a conventional cylinder rod.

FIG. 9 is a side view for explaining a joint type.

FIG. 10 is a time chart showing a pressure welding cycle when friction welding is performed based on standard conditions.

FIG. 11 is a partially enlarged cross-sectional view showing a shape of a burr generated at a joint when friction welding is performed according to the pressure welding cycle of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder rod 2 Rod main body 2a Outer peripheral surface 3 Rod tip member 3a Outer peripheral surface 4 Rod end member 5 Press contact portion 6 Press contact portion 7 Burr 8 Rise portion 8a Start end portion 9 Notch portion 9a Sharp vertex R Curvature radius of start end portion S Virtual plane L Distance between the cusp and the virtual plane

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyoshi Masumoto 3-1-1 Ueno, Hirakata City, Osaka Prefecture F-term in Komatsu Manufacturing Technology Development Center (reference) 3J023 EA03 FA03 GA03 4E067 AA02 BG00 DC02 DC07 EA09 EB00

Claims (4)

[Claims] 1. A joint comprising a carbon steel tubular member (2) frictionally welded to an end face of a carbon steel solid round bar (3) having substantially the same outer diameter as the tubular member (2). , Crimping part (5)
The burr (7) generated on the surface of the material to be pressed (2) (3) rises from the surface (2a) (3a),
A substantially V-shaped notch portion (9) formed substantially at the center of the press contact portion (5), and a radius of curvature (R) of a starting end portion (8a) in the rising portion (8) is approximately 1 mm or more. ,
The distance (L) between the apex (9a) of the notch (9) and the virtual plane (S) connecting the surfaces (2a) and (3a) of the materials to be pressed (2) and (3) is approximately 0. A joint characterized by being at least 5 mm. 2. A cylinder in which a rod tip member (3) is friction-welded to one end surface of a rod body (2), which is a tubular member made of carbon steel, and a rod end member (4) is friction-welded to the other end surface. The rod (1) according to claim 1, wherein at least one of a joint between the rod body (2) and the rod tip member (3) and a joint between the rod body (2) and the rod end member (4). A cylinder rod, which is a joint. 3. A friction step in which a solid round bar (3) made of carbon steel having substantially the same outer diameter as the tubular member (2) is friction-welded to an end face of the tubular member (2) made of carbon steel. Now, the standard speed,
In the upset process, the material to be pressed (2) and (3) is brought into contact with and rotated at a friction pressure lower than the standard friction pressure and at the standard friction shift, and at the upset pressure lower than the standard upset pressure and at the standard upset shift, 2) A method of friction welding a carbon steel tubular member and a solid round bar, wherein the method of (3) is upset. 4. The carbon steel according to claim 3, wherein the friction pressure is about 30 to 50% of the standard friction pressure, and the upset pressure is about twice the friction pressure. A friction welding method between a tubular member and a solid round bar.