JP2012154421A - Method for manufacturing assembly shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an assembly shaft capable of reducing manufacturing cost by the decrease of man days, as a method for manufacturing an assembly shaft such as an assembly camshaft.SOLUTION: An outer circumferential surface 2A of a hollow shaft 2 is plastically deformed for its diameter to be expanded into a deformed cross sectional shape similar to the cross sectional shape of a specified plug, by way of a specified plug penetrating through along an inner surface 2B of the hollow shaft 2, while an outer circumferential surface of an end piece 3 is also plastically deformed for its diameter to be expanded into a deformed cross sectional shape similar to the cross sectional shape of the outer circumferential surface 2A of the hollow shaft 2. As a result, the outer circumferential surface of the hollow shaft 2 is brought to have the end piece 3, cam lobes 4, and journals 5 integrally and tightly attached thereto, while the outer circumferential surface of the end piece 3 has end piece flanges 6 integrally and tightly attached.

Description

  The present invention relates to a method for manufacturing an assembly shaft such as an assembly camshaft, and more particularly to a method for manufacturing an assembly shaft by a plug tube expansion method.

  In general, camshafts for automobile engines are generally integrated camshafts that are manufactured by heat treatment such as machining and surface hardening of semi-finished products for casting and forging. In recent years, assembly camshafts that can contribute to the improvement of the acceleration performance and fuel consumption and that can achieve a reduction in price are becoming popular.

  An assembly camshaft is an assembly in which assembly parts such as cams (cam lobes, cam pieces) and journals are fitted and fixed integrally on the outer peripheral surface of a pipe-shaped hollow shaft. Various manufacturing methods such as a hydraulic expansion method, a diffusion bonding method, a bulge tube expansion method, and a plug tube expansion method are known.

  Each of these manufacturing methods has advantages and disadvantages. Among them, the plug expansion method expands the diameter of the hollow shaft by penetrating the plug (punch) along the inner peripheral surface of the hollow shaft, and the cam ( This is a manufacturing method in which assembly parts such as a cam lobe and a cam piece and a journal are integrally fixed (for example, see Patent Documents 1 to 3), and has an advantage that the working time is extremely short.

  Here, in the manufacture of the assembly-type camshaft, a plurality of concave grooves are formed in advance on the inner peripheral surface of the cam lobe and journal that are fitted to the outer peripheral surface of the hollow shaft. It is described that the cam lobe and the journal are firmly fixed to the outer periphery of the hollow shaft by enlarging the surface with a plug and engaging with the plurality of concave grooves on the inner peripheral surface of the cam lobe and the journal.

  Further, in Patent Document 2, when manufacturing a cam shaft for an engine, a plurality of grooves are formed in advance on the inner peripheral surface of a cam and a bearing ring that are fitted to the outer peripheral surface of the tube (hollow shaft). ) By expanding the outer peripheral surface of the tube (hollow shaft) into a plurality of grooves on the inner peripheral surface of the cam and the bearing ring by the protrusion of the plug (expander tool) inserted along the inner peripheral surface of It is described that a cam and a bearing ring are fixed to the outer peripheral surface of a hollow shaft.

  Further, in Patent Document 3, in manufacturing a camshaft, a steel inner piece is diffusion-bonded in advance to an inner peripheral surface of a sintered metal cam piece fitted to an outer peripheral surface of a shaft (hollow shaft), By making the inner peripheral surface of the inner piece into a polygonal cross-sectional shape, the outer peripheral surface of the shaft (hollow shaft) whose diameter is expanded by the plug is plastically deformed into a polygonal cross-sectional shape that is in close contact with the inner peripheral surface of the inner piece. The cam piece is fixed to the outer periphery of the shaft (hollow shaft).

JP 2000-145411 A JP-A-6-341304 Japanese Patent Laid-Open No. 5-288014

  By the way, in the assembly type camshaft described in Patent Document 1, a plurality of concave grooves are formed in advance on the inner peripheral surface of an assembly part such as a cam lobe or a journal fitted to the outer peripheral surface of the hollow shaft. It is necessary to keep it. Similarly, in the engine camshaft described in Patent Document 2, a plurality of grooves are formed in advance on the inner peripheral surface of an assembly part such as a cam or a bearing ring that fits on the outer peripheral surface of the hollow shaft. It is necessary to keep.

  In addition, in the engine camshaft described in Patent Document 2, the plug (expander tool) projections inserted along the inner peripheral surface of the pipe (hollow shaft), the cam and the bearing ring It is necessary to align the plurality of grooves on the inner peripheral surface in the rotation direction.

  On the other hand, in the camshaft described in Patent Document 3, the inner peripheral surface of the inner piece that is diffusion-bonded in advance to the inner periphery of the sintered metal cam piece is formed in a polygonal cross-sectional shape. There is a need.

  That is, in a plug tube expansion method that is generally known as a manufacturing method of an assembly cam shaft, a plurality of concave grooves or the like are previously provided on the inner peripheral surface of an assembly part such as a cam fitted to the outer peripheral surface of the hollow shaft. The inner peripheral surface of the assembly part must be formed in a polygonal cross-sectional shape, and the assembly part such as a cam is surrounded by the plug inserted through the hollow shaft. There is a problem that a complicated operation of aligning in the direction is necessary, and the number of manufacturing steps is large and the manufacturing cost is increased.

  In addition, as can be seen in Patent Document 1 and the like, in the assembly camshaft that is generally known in the past, it is necessary to connect the end piece to the end of the hollow shaft by a separate means such as friction welding, press-fitting, or shrink fitting. From this point, there is a problem that the number of manufacturing steps is large and the manufacturing cost increases.

  Further, such an end piece is cut out from a solid round bar by a cutting process, and has a problem that it takes a long time to process and the material yield is as low as about 30%.

  The present invention has been made in response to such problems of the prior art, and as a method of manufacturing an assembly shaft such as an assembly camshaft, an assembly shaft manufacturing method capable of reducing the manufacturing cost by reducing the number of manufacturing steps is provided. The issue is to provide.

  In order to solve such a problem, the manufacturing method of the assembly shaft according to the present invention allows a specific plug to pass through the inner peripheral surface of the hollow shaft in a state where the assembly part is fitted to the outer peripheral surface of the hollow shaft. This is a method of manufacturing an assembly shaft of the plug tube expansion method in which the hollow shaft is expanded and the assembly parts are integrally fixed to the outer peripheral surface of the hollow shaft, and the taper that expands the inner peripheral surface of the hollow shaft as a specific plug A plurality of diameter-enlarged circumferential surfaces having an arc-shaped cross-sectional shape that expands the inner circumferential surface of the hollow shaft to a predetermined dimension continuously with the tapered surface, and the inner circumferential surface of the hollow shaft is prevented from being reduced in diameter. A plurality of backup peripheral surfaces having a flat cross-sectional shape, and a plug having an irregular cross-sectional shape in which a plurality of enlarged diameter peripheral surfaces and a plurality of backup peripheral surfaces are alternately arranged is used. .

  In the manufacturing method of the assembly shaft according to the present invention, the specific plug penetrates along the inner peripheral surface of the hollow shaft, so that the tapered surface of the specific plug expands the inner peripheral surface of the hollow shaft, and A plurality of diameter-enlarged peripheral surfaces having an arcuate cross-sectional shape expand the inner peripheral surface of the hollow shaft to a predetermined size. At that time, the plurality of backup peripheral surfaces having a flat cross-sectional shape of the specific plug prevent the inner peripheral surface of the hollow shaft from being reduced in diameter.

  As a result, the inner peripheral surface of the hollow shaft is plastically deformed into a deformed cross-sectional shape that follows the deformed cross-sectional shape of the specific plug, and the diameter of the hollow shaft is expanded. The cross-sectional shape, that is, a deformed cross-sectional shape similar to a specific cross-sectional shape of a specific plug, is plastically deformed and expanded in diameter. As a result, the assembly part fitted to the outer peripheral surface of the hollow shaft is firmly and integrally fixed in the axial direction and the circumferential direction of the hollow shaft.

  A manufacturing method of an assembly shaft according to the present invention includes a cylindrical end piece fitted to an end of a hollow shaft, a ring-shaped end piece flange fitted to the outer periphery of the end piece, and an intermediate portion of the hollow shaft. The present invention can be applied to a method of manufacturing an assembled camshaft that includes a cam lobe and a journal that are fitted to the part as assembly parts.

  In this case, the specific plug penetrates along the inner peripheral surface of the hollow shaft, so that the outer peripheral surface of the hollow shaft is plastically deformed into an irregular cross-sectional shape similar to the irregular cross-sectional shape of the specific plug and is expanded in diameter. . At that time, the inner peripheral surface of the cylindrical end piece fitted to the hollow shaft is plastically deformed into an irregular cross-sectional shape that follows the irregular cross-sectional shape of the outer peripheral surface of the hollow shaft, and the diameter is expanded accordingly. The outer peripheral surface of the end piece is plastically deformed into an irregular cross-sectional shape similar to the irregular cross-sectional shape of the inner peripheral surface, and the diameter is expanded.

  As a result, a cylindrical end piece is integrally fixed to the outer periphery of the end portion of the hollow shaft, and a cam piece and a journal are integrally fixed to the outer periphery of the intermediate portion of the hollow shaft. Shaped end piece flanges are secured together.

  According to the method of manufacturing the assembly shaft according to the present invention, the specific plug is penetrated along the inner peripheral surface of the hollow shaft, so that the outer peripheral surface of the hollow shaft has an irregular shape similar to the irregular sectional shape of the specific plug. The cross-sectional shape can be plastically deformed to expand the diameter, and the assembly part fitted to the outer peripheral surface of the hollow shaft can be firmly and integrally fixed in the axial direction and the peripheral direction of the hollow shaft.

  In particular, according to the manufacturing method of the assembly shaft of the present invention, the cross-sectional shape of the fitting surface of the hollow shaft and the assembly component prepared as a component may remain circular, and the inner peripheral surface of the assembly component may be a polygonal cross-section. Manufacturing of hollow shafts and assembly parts is not necessary because it does not require any additional processing such as forming the shape, forming grooves or protrusions on the inner peripheral surface of the assembly part or the outer peripheral surface of the hollow shaft, or performing knurling. Man-hours can be greatly reduced. Further, the operation of aligning the assembly parts in the circumferential direction of the hollow shaft can be extremely simplified, and the manufacturing cost of the assembly shaft can be greatly reduced.

  Here, a cylindrical end piece fitted to the end portion of the hollow shaft, a ring-shaped end piece flange fitted to the outer periphery of the end piece, a cam lobe fitted to the middle portion of the hollow shaft, and When the assembly shaft manufacturing method of the present invention is applied to the manufacture of an assembly camshaft having a journal as an assembly part, a specific plug is passed through the inner peripheral surface of the hollow shaft to thereby end the hollow shaft. Cylindrical end piece is fixed to the outer periphery of the part, cam lobe and journal are fixed to the outer periphery of the middle part of the hollow shaft, and ring-shaped end piece flange is fixed to the outer periphery of the end piece. it can.

It is sectional drawing which shows schematic structure of the finished product of the assembly camshaft manufactured by the manufacturing method of the assembly shaft which concerns on one Embodiment of this invention. It is a disassembled perspective view of the assembly camshaft shown in FIG. It is sectional drawing which shows the assembly | attachment state of each component of the assembly camshaft shown in FIG. It is a side view which shows the structure of the specific plug used for the manufacturing method of the assembly camshaft shown in FIG. It is the enlarged front view which looked at the specific plug shown in FIG. 4 from the arrow direction. It is explanatory drawing of the radial direction position of the diameter expansion surrounding surface and backup surrounding surface of the specific plug shown in FIG. It is sectional drawing which shows the diameter expansion state of the hollow shaft shown in FIG.

  Hereinafter, an embodiment of a manufacturing method of an assembly shaft according to the present invention will be described with reference to the drawings. An assembly shaft manufacturing method according to an embodiment is a method of manufacturing an assembly camshaft 1 as shown in FIG. 1, for example. First, the assembly camshaft 1 will be described.

  The assembly camshaft 1 constitutes a valve system for an automobile engine (not shown), and is fitted to an outer peripheral surface 2A of one end of a pipe-shaped hollow shaft 2 as shown in FIGS. A cylindrical end piece 3 and a plurality of cam lobes 4, 4... And a plurality of journals 5, 5... Fitted to the outer peripheral surface 2 A of the portion extending from the intermediate portion to the other end of the hollow shaft 2 are provided as assembly parts. ing.

  In addition, the assembly camshaft 1 includes a pair of end piece flanges 6 and 6 fitted to the outer peripheral surface of the end piece 3 as an assembly part.

  The hollow shaft 2 is made of a steel pipe in which the outer peripheral surface 2A and the inner peripheral surface 2B are plastically processed to an appropriate surface roughness, the outer diameter dimension is set to 26 mm, for example, and the inner diameter dimension is set to 16 mm, for example. Yes. On the other hand, the end piece 3 is made of a steel pipe whose outer peripheral surface and inner peripheral surface are plastically processed to an appropriate surface roughness, and the inner diameter dimension thereof can be easily fitted to the outer peripheral surface 2A of the hollow shaft 2. The outer diameter of the hollow shaft 2 is 0.1 to 0.2 mm larger.

  The cam lobes 4, 4... Are forged products or sintered products each having a mounting hole (reference numeral omitted) that fits into the outer peripheral surface 2A of the hollow shaft 2. The inner diameter of the mounting hole is the outer peripheral surface of the hollow shaft 2. The outer diameter of the hollow shaft 2 is 0.1 to 0.2 mm larger so that it can be easily fitted to 2A. The outer peripheral surfaces of the cam lobes 4, 4... Are subjected to appropriate surface hardening treatment such as surface hardening, and the outer peripheral surfaces are ground into a predetermined cam profile after the assembly camshaft 1 is assembled.

  On the other hand, the end piece flanges 6 and 6 are pressed into a ring shape using a plate material, and the inner peripheral surface thereof is the outer diameter of the end piece 3 so that it can be easily fitted to the outer peripheral surface of the end piece 3. 0.1 to 0.2 mm larger than the dimensions.

  Here, the specific plug P shown in FIG. 4 is used for the manufacturing method of the assembly shaft of one Embodiment. This specific plug P is used for expanding the diameter of the hollow shaft 2 shown in FIG. 3, and the plug body P2 is integrally connected to the tip of the shaft portion P1 having a diameter smaller than the inner diameter of the hollow shaft 2. Yes.

  The plug main body P2 is made of, for example, alloy tool steel, and an appropriate surface hardening treatment such as surface hardening is performed on the peripheral surface thereof. As shown in FIG. 5, on the peripheral surface of the plug body P2, a tapered surface P3 for expanding the inner peripheral surface 2B of the hollow shaft 2, and an inner peripheral surface of the hollow shaft 2 continuous with the tapered surface P3. A plurality of enlarged diameter peripheral surfaces P4 having an arc-shaped cross-sectional shape for expanding the diameter of 2B to a predetermined dimension and a plurality of flat sectional shapes for preventing the diameter reduction of the inner peripheral surface 2B of the hollow shaft 2 A backup peripheral surface P5 is formed.

  The taper surface P3 of the plug body P2 has a slope on one side set to 10 °, for example. As shown in FIG. 6, the plurality of diameter-enlarged peripheral surfaces P4 of the plug body P2 are formed along concentric cross-sectional circles whose diameter is about 1 mm larger than the cross-sectional circle of the inner peripheral surface 2B of the hollow shaft 2. . Further, the plurality of backup peripheral surfaces P5 of the plug main body P2 are formed on a flat surface extending along the tangent to the cross-sectional circle of the inner peripheral surface 2B of the hollow shaft 2.

  The plurality of enlarged diameter peripheral surfaces P4 and the plurality of backup peripheral surfaces P5 of the plug body P2 are alternately formed in the circumferential direction, and the plug body P2 has an irregular cross-sectional shape. In the illustrated example, five backup peripheral surfaces P5 are formed along a regular pentagonal outline, and five enlarged peripheral surfaces P4 are formed between the backup peripheral surfaces P5.

  Next, steps of the method for manufacturing the assembly shaft according to the embodiment will be described. First, as shown in FIG. 3, the end piece 3, the cam lobes 4, 4... And the journals 5, 5. At that time, the cam lobes 4, 4... Are held at predetermined positions in the circumferential direction of the hollow shaft 2. The pair of end piece flanges 6 and 6 are fitted in advance at predetermined positions in the axial direction of the end piece 3.

  As described above, the work of assembling the hollow shaft 2, the end piece 3, the cam lobes 4, 4,..., The journals 5, 5,. This is performed using a dedicated bonding machine (not shown) having a plurality of robot hands.

  Next, the plug body P2 of the specific plug P is pressed onto the inner peripheral surface 2B of the hollow shaft 2 by pressing the shaft portion P1 of the specific plug P shown in FIG. Penetrate along.

  Thereby, the taper surface P3 of the plug body P2 pushes and expands the inner peripheral surface 2B of the hollow shaft 2, and a plurality of enlarged diameter peripheral surfaces P4 having a circular cross-sectional shape of the specific plug P are the inner peripheral surface of the hollow shaft 2. The diameter of 2B is increased by about 1 mm in the passing diameter and about 0.5 mm on one side. At that time, the plurality of backup peripheral surfaces P5 having a flat cross-sectional shape of the specific plug P prevent the inner peripheral surface 2B of the hollow shaft 2 from being reduced in diameter.

  As a result, the inner peripheral surface 2B of the hollow shaft 2 is plastically deformed into a deformed cross-sectional shape that follows the deformed cross-sectional shape of the plug body P2, and the diameter is expanded, and the outer peripheral surface 2A of the hollow shaft 2 is The diameter is expanded by plastic deformation to an irregular cross-sectional shape similar to the cross-sectional shape. That is, as shown in FIG. 7, the inner peripheral surface 2B and the outer peripheral surface 2A of the hollow shaft 2 are plastically deformed from a circular cross-sectional shape indicated by a two-dot chain line to an irregular cross-sectional shape indicated by a solid line, and the diameter is increased.

  Similarly, the inner peripheral surface of the end piece 3 is plastically deformed into a deformed cross-sectional shape that follows the deformed cross-sectional shape of the outer peripheral surface 2A of the hollow shaft 2 and expanded in diameter, and the outer peripheral surface of the end piece 3 is its inner peripheral surface. The diameter is expanded by plastic deformation to an irregular cross-sectional shape similar to the irregular cross-sectional shape.

  Here, the inner peripheral surfaces of the end piece 3, the cam lobes 4, 4... And the journals 5, 5... Are plastically deformed into an irregular cross-sectional shape following the outer peripheral surface 2A of the hollow shaft 2, so that the end piece 3, The cam lobes 4, 4 ... and the journals 5, 5 ... are firmly fixed to the outer peripheral surface 2A of the hollow shaft 2 in the circumferential direction.

  Further, the end piece 3, cam lobes 4, 4... And the journals 5, 5. ... and the journals 5, 5, ... are firmly fixed in the axial direction of the hollow shaft 2.

  Furthermore, the outer peripheral surface of the end piece 3 is plastically deformed into an irregular cross-sectional shape and expanded in diameter, and the inner peripheral surfaces of the pair of end piece flanges 6 and 6 are plastically deformed into an irregular cross-sectional shape following this, The pair of end piece flanges 6 and 6 are firmly fixed to the end piece 3 in the circumferential direction.

  Further, between the pair of end piece flanges 6 and 6, the diameter of the outer peripheral surface of the end piece 3 is larger than the inner diameter thereof, so that the pair of end piece flanges 6 and 6 are arranged in the axial direction of the end piece 3. Firmly fixed.

  Thus, as shown in FIG. 1, the cylindrical end piece 3 is integrally fixed to the outer peripheral surface 2 </ b> A of the one end portion of the hollow shaft 2, and the outer peripheral surface 2 </ b> A of the portion extending from the intermediate portion to the other end portion of the hollow shaft 2. The plurality of cam lobes 4, 4... And the plurality of journals 5, 5. Further, a pair of end piece flanges 6 and 6 are integrally fixed to the outer periphery of the end piece 3.

  Therefore, according to the manufacturing method of the assembly shaft of one embodiment, the plug body P2 of the specific plug P is penetrated along the inner peripheral surface 2B of the hollow shaft 2 using a hydraulic cylinder device (not shown) from several seconds. The end piece 3, cam lobes 4, 4..., Journals 5, 5... And end piece flanges 6, 6 are firmly tightened in the axial direction and circumferential direction with respect to the hollow shaft 2. Can be fixed together.

  In particular, according to the method of manufacturing the assembly shaft of the present embodiment, the cross-sectional shape of the fitting surface between the end piece 3, cam lobes 4, 4... And journals 5, 5. Since the cross-sectional shape of the fitting surface between the end piece 3 and the end piece flanges 6 and 6 may remain circular, the cross-sectional shape of these fitting surfaces may be polygonal or these fitting surfaces The manufacturing man-hours of the hollow shaft 2 and the assembly parts can be greatly reduced as compared with those in which concave grooves and protrusions are formed on the inner surface or knurled.

  Further, the alignment of the hollow shaft 2 with the end piece 3, cam lobes 4, 4,... And journals 5, 5,. Can be reduced.

  The manufacturing method of the assembly shaft according to the present invention is not limited to the above-described embodiment. For example, the taper surface P3 formed on the plug body P2 of a specific plug P is not limited to a gradient of 10 ° on one side, but can be changed to a gradient of 5 to 20 °. The diameter of the enlarged peripheral surface P4 may be set larger in the range of 0.5 mm or more than the inner diameter of the inner peripheral surface 2B of the hollow shaft 2 according to the material and dimensions of the hollow shaft 2.

  Furthermore, the backup peripheral surface P5 formed on the plug body P2 may be a flat surface that extends along a tangent to a slightly larger cross-sectional circle than the inner peripheral surface 2B of the hollow shaft 2. And, as shown in FIG. 5, the irregular cross-sectional shape of the plug body P2 in which the five backup peripheral surfaces P5 are formed between the five enlarged peripheral surfaces P4 is, for example, six between the six enlarged peripheral surfaces P4. It can also be changed to an irregular cross-sectional shape in which the backup peripheral surface P5 is formed.

  In addition, the method of manufacturing the assembly shaft according to the present invention is not limited to the assembly cam shaft described above, and it is possible to fit the assembly parts of various shapes to the outer peripheral surface of the hollow shaft of various dimensions and fix them together. For example, the present invention can be applied to the manufacture of a steering shaft mainly composed of a hollow shaft.

1: Assembly camshaft 2: Hollow shaft 2A: Outer peripheral surface 2B: Inner peripheral surface 3: End piece 4: Cam lobe 5: Journal 6: End piece flange P: Specific plug P1: Shaft P2: Plug body P3: Tapered surface P4: Expanded peripheral surface P5: Backup peripheral surface

Claims (2)

By inserting a specific plug along the inner peripheral surface of the hollow shaft with the assembled component fitted to the outer peripheral surface of the hollow shaft, the hollow shaft is expanded in diameter and the assembled component is integrated on the outer peripheral surface. A method of manufacturing an assembly shaft of a plug tube expanding method,
As the specific plug, there are a taper surface that pushes and expands the inner peripheral surface of the hollow shaft, and a plurality of expansions having an arc-shaped cross-sectional shape that expands the inner peripheral surface of the hollow shaft to a predetermined dimension continuously from the taper surface. A plurality of backup peripheral surfaces having a flat cross-sectional shape to prevent diameter reduction of the inner peripheral surface of the hollow shaft, and the plurality of enlarged peripheral surfaces and the plurality of backup peripheral surfaces are alternately arranged. The manufacturing method of the assembly shaft characterized by using the plug which exhibits the unusual cross-sectional shape.   The assembly shaft is fitted to a cylindrical end piece fitted to the end of the hollow shaft, a ring-shaped end piece flange fitted to the outer periphery of the end piece, and an intermediate part of the hollow shaft. 2. The method of manufacturing an assembly shaft according to claim 1, wherein the assembly camshaft includes a cam lobe and a journal as assembly parts.