JP2013124571A - Processing method of sliding surface and camshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of sliding surface, capable of rapidly processing a sliding surface with excellent lubricity, and a camshaft.SOLUTION: In the processing method for sliding surface for forming dimples D which function as an oil basin on sliding surfaces 81a-85a in a camshaft 50 for opening and closing an engine valve 42 by rotating in interlocking with drive of an engine, the dimples D are formed according to the surface pressure P of the sliding surfaces 81a-85a caused according to the biasing force F of a spring 43 biasing the engine valve 42 toward cams 71-74 side.

Description

  The present invention relates to a sliding surface processing method for processing a recess functioning as an oil reservoir on a sliding surface forming an outer peripheral surface of a sliding member, and a camshaft having a sliding surface in which the recess is processed About.

  Many sliding members (rotating bodies) such as camshafts and crankshafts are incorporated in an engine mounted on a vehicle. And by always supplying lubricating oil between the sliding surface of the sliding member and the bearing surface that slidably supports the sliding surface, the friction generated between them is reduced. I have to.

  However, in a low engine speed range, the oil pressure between the sliding surface and the bearing surface decreases, and it is difficult to ensure the lubricating film. Thereby, there is a possibility that the friction generated between them cannot be sufficiently reduced.

  In view of this, a sliding member is provided in which a concave portion functioning as an oil reservoir is formed on the sliding surface for the purpose of reducing the friction in the so-called boundary lubrication state as described above. Such sliding members are disclosed in Patent Documents 1 and 2, for example.

JP 7-133704 A JP 2003-205380 A

  However, in the above-described conventional sliding member, since the recess is formed uniformly over the entire sliding surface, the processing time of the sliding surface may be increased. Moreover, when processing the hollow part into a sliding surface, it is considered to be a good idea to appropriately set the arrangement of the hollow part in consideration of the configuration of the sliding member and the sliding state based on this configuration.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a sliding surface processing method and a camshaft that can process a sliding surface excellent in lubricity in a short time.

The sliding surface processing method according to the first aspect of the present invention for solving the above problems is as follows:
In the processing method of the sliding surface for processing the hollow portion functioning as an oil reservoir with respect to the sliding surface of the camshaft for opening and closing the engine valve of the internal combustion engine by rotating in conjunction with the driving of the internal combustion engine,
The hollow portion is processed according to a surface pressure of the sliding surface that is generated in accordance with a biasing force that biases the engine valve toward the cam side of the camshaft.

The processing method of the sliding surface according to the second invention for solving the above-mentioned problem is as follows.
The hollow portion is processed so that the opening area ratio of the hollow portion gradually decreases as the surface pressure of the sliding surface increases.

A camshaft according to a third invention for solving the above-mentioned problems is
In the camshaft that opens and closes the engine valve of the internal combustion engine by rotating in conjunction with the drive of the internal combustion engine,
A sliding portion supported rotatably;
A cam provided coaxially with the sliding portion and opening the engine valve against a biasing force of a biasing means;
The sliding surface of the sliding portion is provided with a recess portion that is formed according to the surface pressure of the sliding surface that is generated by the biasing force of the biasing means that acts on the cam and functions as an oil reservoir. It is characterized by that.

A camshaft according to a fourth invention for solving the above-mentioned problems is
The opening area ratio of the depression is gradually reduced as the surface pressure of the sliding surface increases.

  Therefore, according to the processing method and the camshaft of the sliding surface according to the present invention, the sliding surface having excellent lubricity is processed in a short time by forming the recess according to the surface pressure of the sliding surface. be able to.

It is a top view of the laser processing apparatus with which the processing method of the sliding face concerning one example of the present invention is applied. It is AA arrow sectional drawing of FIG. It is a schematic block diagram of the camshaft which concerns on one Example of this invention. It is an enlarged view of the cam and sliding part in a cam shaft. It is the figure which showed the opening / closing operation | movement of the engine valve by rotation of a camshaft, (a) is the figure which showed the engine valve fully closed state, (b) is the figure which showed the engine valve fully open state. It is the figure which showed the relationship between the rotation angle of a cam, and the lift amount of an engine valve. It is the figure which showed the relationship between the rotation angle of a cam, the surface pressure of a sliding surface, and the opening area ratio of a dimple.

  Hereinafter, a method for processing a sliding surface and a camshaft according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 3 to 5, the camshaft (workpiece, rotating body, sliding member) 50 constitutes a valve mechanism 40 of a vehicle engine (internal combustion engine). By rotating in conjunction with driving, the valve opening / closing operation of the valve mechanism 40 can be performed. And in the laser processing apparatus 1 shown in FIG.1 and FIG.2, by performing laser processing with respect to the sliding surfaces 81a-85a of the said camshaft 50, the said sliding surfaces 81a-85a are made into an oil reservoir. It is possible to process a functioning dimple (recessed portion, oil groove) D.

  First, the configuration of the camshaft 50, the configuration of the valve operating mechanism 40 in which the camshaft 50 is incorporated, and the valve opening / closing operation will be described in detail with reference to FIGS.

  As shown in FIG. 3, the camshaft 50 includes a shaft portion 61, four pairs of cams 71 to 74 that are a pair of left and right, and sliding portions 81 to 85. The cams 71 to 74 and the sliding portions 81 to 85 are arranged at predetermined intervals in the axial direction of the shaft portion 61. And the sliding part 81 is arrange | positioned at the axial direction outer side of the cam 71, and the sliding parts 82-85 are arrange | positioned between the cams 71-74 of each group. That is, although details will be described later, the cams 71 to 74 and the sliding portions 82 to 85 have a corresponding relationship when the camshaft 50 rotates. Further, the cams 71 to 74 are arranged at equiangular intervals around the axis of the shaft portion 61.

  Further, as shown in FIG. 4, the cams 71 to 74 have a base circle portion 91 and a valve lift portion 92. The cam surface 91a of the base circle portion 91 and the cam surface 92a of the valve lift portion 92 are flush with each other to form a cam surface as a whole of the cams 71 to 74. The engine valve (engine valve) 42 of the engine can be opened and closed by rotating together with the camshaft 50.

  In addition, the base end part of the cams 71-74 used as the center part of the circumferential direction of the cam surface 91a becomes the cam bottom part 91b, and the front-end | tip part of the cams 71-74 used as the top part of the cam surface 92a is the cam top part 92b. It has become. In other words, the cam bottom portion 91b and the cam top portion 92b are arranged 180 degrees apart around the axis of the cams 71 to 74.

  On the other hand, the sliding parts 81-85 have the sliding surfaces 81a-85a which make the outer peripheral surface as mentioned above. These sliding surfaces 81a to 85a are rotatably supported by bearing surfaces of bearings provided in the engine when the camshaft 50 is attached to the engine and the valve mechanism 40.

  5 (a) and 5 (b), the valve operating mechanism 40 includes a bottomed cylindrical valve tappet (driven member) 41, an engine valve 42, a spring, in addition to the cam shaft 50 described above. (Biasing means) 43 and a cylindrical fixing member 44.

  Specifically, the valve tappet 41 is supported by the engine so as to be slidable in the axial direction, and the upper end of the engine valve 42 is connected to the inner surface of the valve tappet 41. At this time, the cam surfaces 91 a and 92 a of the cams 71 to 42 in the camshaft 50 are always in contact with the top surface 41 a of the valve tappet 41.

  Further, a fixing member 44 is fixed to the engine, and an engine valve 42 is inserted into the fixing member 44. A compressed spring 43 is interposed between the inner surface of the valve tappet 41 and the upper surface of the fixing member 44 with the engine valve 42 inserted therein. That is, the valve tappet 41 is always urged upward in the axial direction by the urging force F of the spring 43. Thereby, the top surface 41a of the valve tappet 41 is in a state where the cam surfaces 91a and 92a are always pressed.

  Accordingly, when the camshaft 50 rotates in conjunction with the driving of the engine, as shown in FIGS. 5A and 6, the cam surface 91 a is in rolling contact with the top surface 41 a of the valve tappet 41. The lift amount Lv of the engine valve 42 becomes 0 due to the shape of the cam surface 91a. Thereby, the engine valve 42 is fully closed. The rotation angle θ of the camshaft 50 (cams 71 to 74, sliding portions 82 to 85) shown in FIG. 5A is 0 °.

  Subsequently, as shown in FIGS. 5B and 6, during the period in which the camshaft 50 further rotates and the cam surface 92 a is in rolling contact with the top surface 41 a of the valve tappet 41, the lift of the engine valve 42 is performed. The amount Lv increases from 0 to the maximum and then increases from the maximum to 0 depending on the shape of the cam surface 92a. Thereby, the engine valve 42 gradually shifts from the fully closed state to the fully open state, and then gradually shifts from the fully open state to the fully closed state. Note that the rotation angle θ of the camshaft 50 (cams 71 to 74, sliding portions 82 to 85) shown in FIG. 5B is 180 °.

  Here, as described above, during the valve opening / closing operation of the valve mechanism 40, the top surface 41a of the valve tappet 41 is driven by the biasing force F of the spring 43, and the cam surfaces of the cams 71 to 74 in the cam shaft 50 that rotates. 91a and 92a are always pressed. Thereby, the sliding surfaces 82a to 85a of the sliding portions 82 to 85 in the camshaft 50 have the same magnitude as the urging force F of the spring 43 acting on the cam surfaces 91a and 92a of the cams 71 to 74 corresponding thereto. And, the force in the same direction is applied to the bearing surface as the surface pressure P.

  Such surface pressure characteristics of the sliding surfaces 82a to 85a have the same tendency as the lift amount characteristic of the engine valve 42 shown in FIG. 6, and the characteristic curve of the surface pressure P is shown in FIG. It becomes street.

  That is, as shown in FIG. 7, during the period in which the cam surface 91a is in rolling contact with the top surface 41a of the valve tappet 41, the surface pressure P of the sliding surfaces 82a to 85a is minimized. Further, during the period in which the cam surface 92a is in rolling contact with the top surface 41a of the valve tappet 41, the surface pressure P of the sliding surfaces 82a to 85a gradually changes from the minimum to the maximum, and then gradually increases from the maximum to the minimum. Change.

  Therefore, as shown in FIGS. 5 to 7, while the cam surface 91 a is in contact with the top surface 41 a of the valve tappet 41, the valve tappet 41 and the engine valve 42 are pushed up by the urging force F of the spring 43. ing. As a result, the lift amount Lv of the engine valve 42 becomes 0, and the engine valve 42 is fully closed. Further, the surface pressure P of the sliding surfaces 82a to 85a is minimized.

  Next, when the cam surface 92a is transferred to the top surface 41a of the valve tappet 41, the valve tappet 41 and the engine valve 42 are gradually pushed down against the urging force F of the spring 43 by the cam surface 92a. As a result, the lift amount Lv of the engine valve 42 and the surface pressure P of the sliding surfaces 82a to 85a gradually increase as the cam top portion 92b of the cam surface 92a approaches the top surface 41a of the valve tappet 41. 42 begins to open gradually.

  When the cam top portion 92b of the cam surface 92a reaches the top surface 41a of the valve tappet 41 (when the rotation angle θ of the camshaft 50 reaches 180 °), the valve tappet 41 and the engine valve 42 are connected to the cam surface 92a. Thus, the spring 43 is further pushed down against the urging force F of the spring 43. Thereby, the lift amount Lv of the engine valve 42 and the surface pressure P of the sliding surfaces 82a to 85a are maximized, and the engine valve 42 is fully opened.

  Next, when the cam top portion 92 b of the cam surface 92 a is separated from the top surface 41 a of the valve tappet 41, the valve tappet 41 and the engine valve 42 are gradually pushed up by the urging force F of the spring 43. As a result, the lift amount Lv of the engine valve 42 and the surface pressure P of the sliding surfaces 82a to 85a gradually decrease as the cam top portion 92b of the cam surface 92a moves away from the top surface 41a of the valve tappet 41. 42 begins to close gradually.

  When the cam surface 91 a is transferred to the top surface 41 a of the valve tappet 41, the valve tappet 41 and the engine valve 42 are further pushed up by the urging force F of the spring 43. As a result, the shift amount Lv of the engine valve 42 becomes 0, and the engine valve 43 is fully closed. Further, the surface pressure P of the sliding surfaces 82a to 85a is minimized.

  Next, the configuration of the laser processing apparatus 1 will be described in detail with reference to FIGS. 1, 2, and 4.

  As shown in FIG.1 and FIG.2, the laser processing apparatus 1 is comprised from the laser processing unit 11 and the workpiece | work mounting unit 12, and the bed 13 which has these units 11 and 12 in the upper part.

  The workpiece mounting unit 12 allows the above-described cam shaft 50 to be detachable in a state where the axis of the shaft portion 61 is arranged in the X-axis direction. The laser processing unit 11 performs laser processing on the camshaft 50 mounted on the workpiece mounting unit 12 from the Z-axis direction orthogonal to the X-axis direction.

  An X-axis moving body 21 is provided below the laser processing unit 11, and the X-axis moving body 21 is supported on the upper surface of the bed 13 so as to be movable in the X-axis direction. Further, a Z-axis moving body 22 is supported on the upper surface of the X-axis moving body 21 so as to be movable in the Z-axis direction. A laser oscillator 23 is provided above the Z-axis moving body 22, and a condenser lens 25 is provided via an attachment member 24. At this time, the laser oscillator 23 and the condenser lens 25 are provided to face each other in the Z-axis direction, and the laser light L output from the laser oscillator 23 passes through the condenser lens 25. Focused.

  Accordingly, by driving the X-axis moving body 21 and the Z-axis moving body 22, the laser oscillator 23 and the condenser lens 25 are moved in the X-axis direction (the axial direction of the camshaft 50) and the Z-axis direction (the radial direction of the camshaft 50). ).

  Here, the drive of the Z-axis moving body 22 is not only used for movement and positioning in the Z-axis direction in the laser oscillator 23 but also for adjusting the condensing position of the laser light L by the condensing lens 25. Also used. That is, by driving the Z-axis moving body 22, the condensing position of the laser light L by the condensing lens 25 can be moved in the Z-axis direction. Further, the laser oscillator 23 can adjust the energy density, the irradiation time (output time), and the number of irradiation times of the laser beam L to be output. That is, by adjusting the energy density, the irradiation time, the number of times of irradiation of the laser beam L output from the laser oscillator 23, and the amount of movement of the condenser lens 25 in the Z-axis direction, the laser beam L is applied to the sliding surfaces 81a to 85a. The diameter (opening area) and depth of the dimple D processed when irradiated can be adjusted (see FIG. 4).

  A work spindle 31 and a work support 32 are respectively provided on both sides of the work mounting unit 12 in the X-axis direction. The work spindle 31 and the work support 32 are supported on the upper surface of the bed 13 so as to be movable in the X-axis direction so as to approach and separate from each other.

  A work spindle 31a is rotatably supported inside the work spindle base 31, and the work spindle 31a can be driven to rotate at a predetermined rotational speed and can hold one end of the camshaft 50. Yes. In addition, an encoder 33 is connected to the work spindle 31, and this encoder 33 can detect the rotation angle of the work spindle 31 a (the rotation angle θ of the camshaft 50 described above).

  On the other hand, a center member 32a is rotatably supported inside the work support base 32. The center member 32a is disposed coaxially with the work spindle 31a and can hold the other end of the camshaft 50.

  Therefore, the camshaft 50 can be attached and detached by moving the work spindle 31a of the work spindle 31 and the center member 32a of the work support base 32 closer to and away from each other in the X-axis direction. Further, the camshaft 50 can be rotated around its axis by rotating the work spindle 31a while the camshaft 50 is sandwiched between the work spindle 31a and the center member 32a. At this time, as shown in FIG. 4, the laser light L output from the laser oscillator 23 is condensed by the condensing lens 25 and irradiated on the sliding surfaces 81 a to 85 a, so that the sliding surfaces 81 a to 81 a. With respect to 85a, a fine dimple D that functions as an oil reservoir can be processed.

  Next, the operation of the laser processing apparatus 1 will be described in detail with reference to FIGS. 1, 2, 4, and 7.

  As shown in FIGS. 1 and 2, first, after the camshaft 50 is mounted between the work spindle base 31 and the work support base 32, the camshaft 50 is rotated by rotationally driving the work spindle 31a. .

  Next, by driving the X-axis moving body 21 and the Z-axis moving body 22, the laser oscillator 23 and the condenser lens 25 are opposed to the sliding surface 82 a of the sliding portion 82 corresponding to the cam 71.

  Then, after adjusting the energy density, irradiation time, number of times of irradiation, and condensing position of the laser light L according to the diameter and depth of the dimple D processed into the sliding surface 82a, the laser oscillator 23 is driven, Laser light L is applied to the sliding surface 82a. Thereby, a plurality of dimples D are processed on the sliding surface 82a (see FIG. 4).

  At this time, by detecting the rotation angle θ of the camshaft 50 (work spindle 31a), the movement of the laser oscillator 23 in the X-axis direction and the rotation speed of the camshaft 50 (work spindle 31a) are controlled. The dimples D formed on the moving surface 82a are processed according to the surface pressure P of the sliding surface 82a generated with the urging force F of the spring 43 acting on the cam 71. That is, as shown in FIG. 7, the opening area ratio R of the dimple D formed on the sliding surface 82a is gradually decreased as the surface pressure P of the sliding surface 82a increases. The opening area ratio R indicates the ratio of the opening area of the dimple D to the area of the sliding surface 82a.

  Specifically, since the surface pressure P is minimized at the sliding surface 82a facing the cam surface 91a, the opening area ratio R of the dimple D is maximized. Further, in the sliding surface 82a facing the cam surface 92a, the surface pressure P gradually changes from the minimum to the maximum as it goes to the position facing the cam top portion 92b. It gradually changes from the maximum to the minimum as it goes to the position facing the cam top portion 92b (near the tip of the arrow indicating the surface pressure P in FIG. 5B).

  Therefore, in the portion where the surface pressure P on the sliding surface 82a becomes large, the opening area ratio R of the dimple D is made small in order to secure the strength rather than the lubricity. On the other hand, in the portion where the surface pressure P on the sliding surface 82a is small, the opening area ratio R of the dimple D is increased in order to ensure lubricity rather than strength. As a result, the processing time can be shortened compared with the case where the dimple D is processed uniformly over the entire sliding surface 82a.

  Next, as described above, when the laser processing on the sliding surface 82a is completed, the laser processing on the sliding surfaces 83a to 85a is sequentially performed. Further, laser processing may be performed on the sliding surface 81a in the same manner as the sliding surface 82a.

  In the above-described embodiment, the workpiece to be processed by the laser processing apparatus 1 is the camshaft 50. However, in the laser processing apparatus 1, for example, a crankshaft employed in a vehicle engine is processed. It is also possible.

  Therefore, in the camshaft 50, the dimples D that function as oil reservoirs are formed according to the surface pressure P of the sliding surfaces 81a to 85a, so that the sliding surfaces 81a to 85a having excellent lubricity can be processed in a short time. can do. In addition, by forming the dimples D on the sliding surfaces 81a to 85a as described above, it is possible to achieve both lubricity and strength in the sliding surfaces 81a to 85a.

  The present invention can be applied to a laser processing apparatus that irradiates a sliding surface that forms the inner peripheral surface of a sliding member with laser light to process a recess that functions as an oil reservoir.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 11 Laser processing unit 12 Work mounting unit 23 Laser oscillator 25 Condensing lens 31 Work spindle stand 32 Work support stand 40 Valve mechanism 41 Valve tappet 41a Top surface 42 Engine valve 43 Spring 44 Fixing member 50 Cam shaft 61 Axis Portions 71 to 74 Cams 81 to 85 Sliding portions 81a to 85a Sliding surfaces 91 Base circular portions 91a Cam surfaces 91b Cam bottom portions 92 Valve lift portions 92a Cam surfaces 92b Cam top portions L Laser light D Dimples θ Rotation angle Lv Lift amount F Energizing force P Surface pressure R Opening area ratio

Claims (4)

In the processing method of the sliding surface for processing the hollow portion functioning as an oil reservoir with respect to the sliding surface of the camshaft for opening and closing the engine valve of the internal combustion engine by rotating in conjunction with the driving of the internal combustion engine,
The method of processing a sliding surface, wherein the hollow portion is processed according to a surface pressure of the sliding surface generated by a biasing force that biases the engine valve toward the cam side of the camshaft. In the processing method of the sliding face according to claim 2,
The sliding surface processing method, wherein the recess portion is processed so that an opening area ratio of the recess portion gradually decreases as the surface pressure of the sliding surface increases. In the camshaft that opens and closes the engine valve of the internal combustion engine by rotating in conjunction with the drive of the internal combustion engine,
A sliding portion supported rotatably;
A cam provided coaxially with the sliding portion and opening the engine valve against a biasing force of a biasing means;
The sliding surface of the sliding portion is provided with a recess portion that is formed according to the surface pressure of the sliding surface that is generated by the biasing force of the biasing means that acts on the cam and functions as an oil reservoir. A camshaft characterized by that. The camshaft according to claim 3,
The camshaft characterized by gradually decreasing the opening area ratio of the recess as the surface pressure of the sliding surface increases.

Images