JP6233290B2 - Camshaft manufacturing equipment - Google Patents

Description

  The present invention relates to a camshaft manufacturing apparatus that drives, for example, an intake valve and an exhaust valve of an engine, and more particularly to an assembling process in which a cam piece is assembled to a shaft.

  2. Description of the Related Art Conventionally, as a camshaft of a valve train system for driving an intake valve or an exhaust valve of an engine, a cam piece is formed separately from the shaft and assembled by shrink fitting (tight fitting). . As such an assembly-type camshaft manufacturing apparatus, for example, the one disclosed in Patent Document 1 is heated in a state where the cam piece is held by a clamper, inserted into the expanded shaft hole, and then cooled. I have to.

  In this manufacturing apparatus, a clamper is disposed on each of a plurality of tables arranged vertically, and a plurality of cam pieces are held in directions corresponding to phases to be assembled to the shaft. The clamper has a pair of opposing clamp members, and the clamp member on one side has a V-shaped recess that grips the cam lobe portion of the cam piece from the tip side, and the clamp member on the other side is the base It has a recess with an arc-shaped cross section that grips the part.

JP 2003-227560 A

  However, even if the cam piece is gripped by the pair of clamp members as described above, when the shaft is inserted into the shaft hole, the direction of the cam piece is caused by friction between the outer peripheral surface of the shaft and the inner peripheral surface of the shaft hole. May be slightly shifted. That is, the inner peripheral surface of the shaft hole of the cam piece is roughened to ensure the joining torque after shrink fitting, and even if it is expanded by heating, This is because a frictional force exceeding a certain level is generated.

  If the orientation of the cam piece is shifted when assembling to the shaft in this way, the phase of the cam lobe in the completed camshaft will slightly shift, and in the valve train of the engine incorporating this camshaft, the intake valve and exhaust Variations occur in the timing at which the valve operates. This increases the combustion variation for each cylinder of the multi-cylinder engine, which may cause problems such as increased vibration and decreased output.

  In view of this point, an object of the present invention is to substantially eliminate the cam lobe phase shift by eliminating the cam piece shift assembled to the shaft as much as possible when manufacturing the camshaft used in the valve train system of the engine. It is in.

  In order to achieve the above object, the present invention is directed to a camshaft manufacturing apparatus in which a cam piece is assembled to a shaft, and the cam piece is inserted into a shaft hole provided in the cam piece. A positioning member that presses the outer periphery of the cam lobe and positions the shaft relative to the shaft, and a vibration means that vibrates the cam piece via the positioning member.

  The positioning member is provided with a pair of rolling members so as to sandwich the cam lobe portion from the tip side thereof, and is provided so as to be able to roll around an axis extending in the longitudinal direction of the shaft. As the rolling member, for example, a roller or a ball may be used, or a roller bearing, a ball bearing, or the like may be used.

  In the manufacturing apparatus configured as described above, for example, in the case of shrink fitting, the outer periphery of the cam lobe portion of the cam piece is inserted in a state where the shaft is inserted into the shaft hole of the cam piece heated to a predetermined temperature or higher and expanded. It is pressed by the positioning member, and the cam piece is rotated around the shaft for positioning. That is, the positioning member is provided with a pair of rolling members so as to sandwich the cam lobe portion from the front end side and presses the outer periphery of the cam lobe portion, so that the cam piece is temporarily deviated in the circumferential direction of the shaft. If so, the displaced rolling member presses the cam lobe portion more strongly, and the cam piece is rotated in a direction in which the displacement becomes smaller.

  Thus, when the cam piece rotates around the shaft, the rolling member that presses the cam lobe part rolls, so that the cam piece does not interfere with the rotation of the cam piece due to friction with the cam lobe part. Moreover, the cam piece rotated in this way can reduce the friction between the inner peripheral surface of the shaft hole and the outer peripheral surface of the shaft by vibrating through the positioning member.

  In other words, the friction between the cam piece and the positioning member is minimized by the rolling member, and the friction between the cam piece and the shaft can be effectively reduced by the vibration of the cam piece. It can be rotated around the shaft to adjust its position accurately. Therefore, the cam lobe phase shift can be substantially eliminated.

  When adjusting the position by rotating the cam piece as described above, in order to effectively reduce the friction between the inner peripheral surface of the shaft hole and the outer peripheral surface of the shaft, vibration applied to the cam piece is so-called high-frequency vibration. It is preferable that For example, an ultrasonic transducer can be used as the vibration means for that purpose. Moreover, what is necessary is just to let the direction to vibrate be the direction which presses a cam piece with a positioning member, for example.

  In other words, the present invention relates to a method of manufacturing a camshaft by assembling the campiece to the shaft, and the campiece is heated to a predetermined temperature or more to expand its shaft hole, and the shaft is inserted and held therein. And a step of pressing the outer periphery of the cam lobe portion of the cam piece in this state with a positioning member and rotating the cam piece around the shaft.

  The positioning member is provided with a pair of rolling members so as to sandwich the cam lobe portion from the tip side thereof, and is provided so as to be able to roll around an axis extending in the longitudinal direction of the shaft. In the positioning step, the cam piece is vibrated through the positioning member by the vibration device.

  In the camshaft manufacturing apparatus according to the present invention, the cam piece is positioned in a state where the shaft is inserted into the shaft hole. In addition, by vibrating the cam piece during positioning, friction between the shaft and the shaft can be effectively reduced, and the positioning member presses the cam piece via the rolling member. The cam piece can be rotated without being adjusted, and the position thereof can be adjusted accurately.

  Therefore, the cam lobe phase shift in the completed camshaft can be substantially eliminated, and an increase in vibration and a decrease in output of the engine incorporating this camshaft can be effectively suppressed.

It is a perspective view which shows the principal part structure of the manufacturing apparatus of the cam shaft which concerns on embodiment. FIG. 2 is a view corresponding to FIG. 1 showing a state in which a positioning chuck is pressed against a cam lobe portion to position a cam piece. It is an image figure which adjusts the position of a cam piece by pressing a positioning chuck. It is a flowchart figure which shows the manufacture procedure of the camshaft which concerns on embodiment. It is a perspective view which shows an example of the cam shaft which concerns on embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case will be described in which the present invention is applied to a camshaft manufacturing apparatus provided in a valve train of an engine. An example of the camshaft CS of the present embodiment shown in FIG. 5 is used for a V-type 6-cylinder engine, for example, and six cam lobes c2 corresponding to three cylinders in one bank are separated in the axial direction of the shaft S. In addition, the two are provided as a set with a phase difference of 120 degrees in the circumferential direction.

  The camshaft CS of the present embodiment is an assembly type in which the cam piece C is formed separately from the shaft S and is assembled to the shaft S by shrink fitting (interference fitting). The assembly phase angle (the circumferential position around the shaft S) of each cam piece C with respect to the shaft S is set at the time of assembly corresponding to the phase angle of the cam lobe portion c2 in the completed camshaft CS.

  The shaft S is a shaft member made of a metal material such as carbon steel for mechanical structure and formed in a solid or hollow shape. The cam piece C is made of a highly wear-resistant metal material such as a forged product or a sintered material, and is formed in a thick plate shape having an oval outer shape as a whole. Specifically, the cam piece C is formed by integrally forming a perfect base portion c1 and a cam lobe portion c2 projecting outward, and a shaft S is provided in a shaft hole c3 provided concentrically with the base portion c1. It is designed to be inserted.

  Since the camshaft CS incorporated in the engine rotates at a high speed such as 7000 rpm at maximum, the shaft hole c3 of the cam piece C is firmly fixed to the shaft S by an interference fit. Furthermore, in this embodiment, in order to ensure a required joining torque, the inner peripheral surface of the shaft hole c3 which is a joining surface is subjected to a roughening process using a laser or the like.

-Manufacturing equipment-
Although only the main part is schematically shown in FIG. 1, the camshaft manufacturing apparatus 1 according to this embodiment includes a plurality of cam tables 2 on which cam pieces C are placed. Although only the uppermost cam table 2 is shown in FIG. 1, a plurality of cam tables 2 are provided side by side, and the cam pieces C placed on each cam table 2 have their respective assembly phase angles. It is positioned in the direction corresponding to. A shaft S is supported above the cam piece C so as to extend in the vertical direction (Z direction).

  Here, the cam piece C placed on the cam table 2 is heated and expanded as described later, and the inner diameter of the shaft hole c3 is larger than the outer diameter of the shaft S. And the shaft hole c3 of the cam piece C mounted on the several cam table 2 is arrange | positioned so that it may correspond substantially seeing to an up-down direction. Therefore, the plurality of cam pieces C can be assembled to the shaft S by moving the upper shaft S downward and sequentially inserting it from the shaft hole c3 of the uppermost cam piece C.

  Specifically, the cam table 2 has a flat plate shape, and a shaft insertion hole 21 having a size through which the shaft S is inserted with a margin is opened at a substantially central portion of the upper surface thereof. A plurality of pins 22 for temporarily positioning the cam piece C are disposed on the upper surface of the cam table 2 so as to surround the opening of the shaft insertion hole 21. The cam piece C is roughly positioned by these pins 22 so that the shaft hole c3 is included in the shaft insertion hole 21 when viewed in the vertical direction, and the cam lobe portion c2 faces the positioning chuck 3 (described later). Is done.

  In addition, the cam table 2 has an assembly position (position shown in the figure) where the cam piece C is assembled to the shaft S as described above, and a retreat position (see FIG. 1) away from the assembly position in the left-right direction (Y direction) in FIG. 1) to the left side of FIG. A notch portion 23 is provided so as to communicate with the shaft insertion hole 21 through which the shaft S is inserted at the assembly position and to be opened to the side of the cam table 2 (for example, the right side in the figure). .

  Thus, both the shaft insertion hole 21 and the cutout portion 23 communicating with each other have an opening width with a sufficient margin with respect to the outer diameter of the shaft S. In particular, the cutout portion 23 has a shaft insertion hole. As the distance from 21 increases, the width increases. When the cam table 2 moves horizontally toward the retracted position as described above, the shaft S is extracted from the cam table 2 with a margin through the notch 23.

-Phase determination mechanism-
A circumferential position of the cam piece C with respect to the shaft S so as to face the nose of the cam piece C placed on the cam table 2 and positioned roughly by the pin 22 (the tip of the cam lobe portion c2) ( That is, a positioning chuck 3 (positioning member) for determining the phase of the cam lobe c2 is provided.

  The positioning chuck 3 is attached to the tip of an arm 4 of a slide mechanism (not shown), and the arm 4 is moved in the front-rear direction (X direction in FIG. 1) by an actuator (not shown). As shown, the cam piece C advances and retreats. Then, as shown in FIG. 2, the positioning chuck 3 presses the outer periphery of the cam lobe portion c <b> 2 of the cam piece C toward the shaft S at the advanced position.

  As schematically shown in FIG. 3, the positioning chuck 3 of the present embodiment has two left and right finger portions 31 each having a front portion divided into two, and each of the finger portions 31 is provided on both of the finger portions 31. The roller 32 (rolling member) presses the cam lobe part c2 so as to be sandwiched from the tip side. The roller 32 is rotatably provided at the tip end of the finger portion 31 via a support shaft 33 extending vertically, and the outer periphery thereof is positioned in front of the finger portion 31.

  When the cam lobe portion c2 is pressed so as to be sandwiched between the pair of rollers 32 from the front end side in this way, as shown schematically in FIG. 3A, the left side roller 32 presses the left side surface of the cam lobe portion c2. Then, the direction of the cam piece C changes so that the right roller 32 balances the force f2 that presses the right side of the cam lobe portion c2, and the cam piece C faces the center of the pair of rollers 32.

  Specifically, as exaggeratedly shown in FIG. 3B, for example, when the nose of the cam piece C is shifted to the left side, the force f1 that presses the left side surface of the cam lobe c2 is greater than the force f2 that presses the right side surface. Since it becomes large, the cam piece C turns to the right side (that is, in a direction to eliminate the deviation). In FIG. 3B, the right roller 32 is exaggerated so as to be separated from the right side surface of the cam lobe portion c2. However, if the displacement is smaller, the cam lobe portion c2 is microscopically viewed. The roller 32 comes into contact with the right side surface, and a force f2 indicated by an imaginary line is applied.

  In this way, the left and right side surfaces of the cam lobe portion c2 are pressed by the left and right rollers 32, respectively, and as shown in FIG. 3A, the cam lobe portion c2 from the center (axial center) of the shaft hole c3 of the cam piece C. The direction of the cam piece C is at an appropriate position so that the line segment V (direction of the cam piece C) toward the apex (cam nose) and the line segment L connecting the shaft centers of the support shafts 33 of the pair of rollers 32 are orthogonal to each other. Will settle down.

  However, as described above, the inner peripheral surface of the shaft hole c3 of the cam piece C is roughened to ensure a joining torque that can withstand high-speed rotation of the camshaft CS. Even if heated and expanded, some frictional force is generated between the shaft S and the outer peripheral surface. Then, the frictional force hinders the rotation of the cam piece C as described above, so that the position of the cam piece C may slightly shift from the proper position.

  On the other hand, in the present embodiment, an ultrasonic vibrator 5 (vibration means) made of, for example, a piezoelectric element is disposed between the positioning chuck 3 and the arm 4, and the position of the cam piece C (cam lobe) as described above. When adjusting the phase of the portion c2, the cam piece C is vibrated at a high frequency via the positioning chuck 3. Thus, the friction between the inner peripheral surface of the shaft hole c3 of the cam piece C and the outer peripheral surface of the shaft S can be effectively reduced, and the cam piece C can easily rotate around the shaft S.

  The ultrasonic transducer 5 is, for example, a known one formed by laminating a plurality of piezoelectric ceramic elements, and can excite vibration by applying an AC voltage between the electrodes. In the present embodiment, the piezoelectric ceramic elements are arranged between the arm 4 so that the stacking direction of the piezoelectric ceramic elements is the pressing direction of the cam piece C by the positioning chuck 3, so that vibration is applied in this pressing direction. However, the present invention is not limited to this. For example, vibration may be performed in a direction orthogonal to the pressing direction.

-Camshaft manufacturing procedure-
Next, a procedure for manufacturing the camshaft CS by the manufacturing apparatus 1 having the above-described configuration will be described with reference to the flowchart of FIG. First, in the first step ST1, the cam piece C is heated to a predetermined temperature by a heater or an induction heating device (not shown). The inner diameter of the shaft hole c3 of the cam piece C is smaller than the outer diameter of the shaft S at room temperature, but the inner diameter of the shaft hole c3 is larger than the outer diameter of the shaft S if it is heated to about 250 to 300 ° C. higher than the room temperature. Is increased by a predetermined dimension, and the shaft S can be inserted without difficulty.

  The cam piece C heated to a predetermined temperature is conveyed to the cam table 2 by a slider or a robot (not shown) (shown schematically as an arrow T in FIG. 1) and set on the cam table 2 (steps). ST2: Cam piece supply). At this time, the cam piece C is roughly positioned by the pins 22 provided on the cam table 2, and the shaft hole c3 is included in the shaft insertion hole 21 of the cam table 2 when viewed in the vertical direction (step ST3: Rough positioning).

  In this state, the shaft S is lowered from above and inserted into the shaft hole c3 of the cam piece C set on the uppermost cam table 2, and the shaft S is further lowered so that the second, third, etc. from above. Each is inserted into the shaft holes c3 of the plurality of cam pieces C in order (step ST4: shaft insertion). At this time, even if the position of the shaft hole c3 is slightly deviated, the deviation of this position is absorbed by the movement of the cam piece C.

  The positioning chuck 3 is pressed against the outer periphery of the cam lobe portion c2 of each cam piece C and pressed toward the shaft S in a state where the shaft S is inserted through the shaft holes c3 of the plurality of cam pieces C. As a result, the cam piece C rotates around the shaft S to an appropriate position as described above with reference to FIG. That is, the position of the cam piece C is adjusted so that the phase shift of the cam lobe part c2 is eliminated (step ST5: cam lobe phase adjustment).

  At this time, an AC voltage having a predetermined frequency is applied to the ultrasonic vibrator 5 from a control circuit (not shown), and the cam piece C is vibrated at a high frequency via the positioning chuck 3. Thereby, the friction between the inner peripheral surface of the shaft hole c3 of the cam piece C and the outer peripheral surface of the shaft S is reduced, and the cam piece C is not substantially inhibited from rotating around the shaft S. Therefore, the cam piece C can be rotated to the proper position described above with reference to FIG.

  Then, when the cam piece C is rotated and held at an appropriate position and cooled by blowing air, for example, the shaft hole c3 contracts as the temperature decreases, and the cam piece C is tightened on the outer periphery of the shaft S. It is fixed by fitting (step ST6: shrink fitting is completed). Therefore, if the cam table 2 is moved to the retracted position, the shaft S (finished camshaft CS) in which the plurality of cam pieces C are assembled at predetermined positions can be taken out.

  As described above, in the camshaft manufacturing apparatus 1 of the present embodiment, first, the outer periphery of the cam lobe portion c2 of the cam piece C with the shaft S inserted through the shaft hole c3 of the cam piece C heated to a predetermined temperature or higher. Is pressed by the positioning chuck 3 and rotated around the shaft S so as to be positioned.

  Further, when rotating around the shaft S, the cam piece C can be vibrated at a high frequency via the positioning chuck 3 to reduce friction between the cam piece C and the cam piece C. Since the roller 32 that presses the cam lobe portion c2 is rotated with the rotation of the cam piece C, the rotation of the cam piece C is not hindered by the friction with the positioning chuck 3.

  That is, since the cam piece C can be rotated around the shaft S without being hindered by friction and the position thereof can be accurately adjusted, the phase shift of the cam lobe c2 in the completed camshaft CS is substantially reduced. Can be resolved. And the combustion dispersion | variation for every cylinder of the engine incorporating this camshaft CS can be made small enough, for example, malfunctions, such as an increase in a vibration and a fall of an output, can be suppressed effectively.

-Other embodiments-
The present invention is not limited to the description of the above-described embodiment. The description of the embodiment is merely an example, and the configuration and application of the present invention are not limited. For example, in the above-described embodiment, the camshaft CS used for the valve operating system of the V-type 6-cylinder engine has been described. There may be. Further, the present invention can be applied to a camshaft other than the valve train of the engine, and also to a camshaft other than the engine.

  In the camshaft CS of the above embodiment, the cam piece C is assembled to the shaft S by shrink fitting, but this may be cold fitting. In the embodiment, the positioning chuck 3 presses the cam lobe portion c2 of the cam piece C through the roller 32. However, a ball may be used instead of the roller 32, or a roller bearing, a ball bearing, or a needle bearing. Etc. can also be used.

  Furthermore, in the above-described embodiment, the ultrasonic vibrator 5 using a piezoelectric element is interposed between the positioning chuck 3 and the arm 4 as a vibration means. An ultrasonic vibrator using an element may be used as the vibration means, or a vibration means other than the ultrasonic vibrator may be used.

  Furthermore, in the above-described embodiment, the camshaft manufacturing apparatus 1 is provided with a plurality of cam tables 2, and a plurality of cam pieces C mounted on the cam table 2 are assembled to the shaft S at the same time. However, the present invention is not limited to this. . If only one cam table 2 is provided, and one cam piece C is placed on the cam table 2 and assembled to the shaft S, the configuration of the apparatus can be simplified. In this case, the difference in the assembly phase angle for each cam piece C can be absorbed by rotating the shaft S around its axis.

  The present invention can substantially eliminate the cam lobe phase shift in the camshaft and can suppress an increase in vibration or a decrease in output of an engine incorporating the camshaft. Highly effective when applied to engine camshafts.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Cam table 3 Positioning chuck (positioning member)
32 Roller (rolling member)
33 Support shaft (axis extending in the longitudinal direction of the shaft)
4 arm 5 ultrasonic transducer (vibration means)
CS Camshaft C Cam piece c1 Base part c2 Cam lobe part c3 Shaft hole S Shaft

Claims (1)

A camshaft manufacturing apparatus in which a cam piece is assembled to a shaft,
A positioning member that presses the outer periphery of the cam lobe portion in the cam piece and positions the shaft relative to the shaft in a state where the shaft is inserted into the shaft hole provided in the cam piece;
Vibration means for vibrating the cam piece via the positioning member, and
The positioning member is provided with a pair of rolling members so as to sandwich the cam lobe portion from the tip side thereof, and is provided so as to be able to roll around an axis extending in the longitudinal direction of the shaft. An apparatus for manufacturing a camshaft.

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