JP2022074168A - Surface processing method of member having penetration hole at bottom wall part of recess, manufacturing method of oil pump and oil pump - Google Patents

Abstract

To improve a tool life of an end mill while securing the flatness of a bottom face of a recess.SOLUTION: A housing 6 formed of an aluminum alloy material has a bottom wall part 10 which is formed into a relatively-thin thickness, and a circular disc-shaped peripheral wall part 11 erecting from an outer edge of the bottom wall part 10. A penetration hole 10a is penetratingly formed at a center of the bottom wall part 10. A bottom face 28 and a side face 11a of a recess 6a which is formed of the bottom wall part 10 and the peripheral wall part 11 are applied with cut processing by a first end mill 53. At the cut processing, a sending direction of the first end mill 53 is inverted after processing a peripheral part 30 by moving the first end mill 53 to the fixed-state housing 6 so as to go around the peripheral part 30 in a clockwise direction (sending direction V), and a peripheral wall part adjoining part 31 and the side face 11a are processed by moving the first end mill 53 so as to go around in an anti-clockwise direction (sending direction W).SELECTED DRAWING: Figure 12

Description

The present invention relates to a method for surface processing a member having a through hole in a bottom wall portion of a recess, a method for manufacturing an oil pump, and an oil pump.

The oil pump described in Patent Document 1 has a housing in which a recess is formed, and a pump structure having an inner rotor, an outer rotor, and the like is arranged in the recess of the housing. Further, a through hole is provided on the bottom surface of the recess, and a drive shaft for rotationally driving the inner rotor is inserted into the through hole.

Since the bottom surface of the recess forms a part of the hydraulic oil chamber formed inside the housing, it is a portion that affects the sealing property of the hydraulic oil chamber. Therefore, the bottom surface of the recess is finished by using an end mill in order to obtain the sealing property of the hydraulic oil chamber, whereby high flatness is ensured. This bottom surface finishing process is performed by orbiting the end mill relatively around the through hole. Further, when finishing the bottom surface, the side surface of the recess is also processed. Generally, when processing the side surface, the side surface is cut by a so-called downcut. This is to extend the tool life of the end mill, and the side surface is cut by reversing the circumferential direction of the end mill with respect to the rotation direction of the end mill.

Japanese Unexamined Patent Publication No. 2007-85262

When machining the bottom surface with an end mill in a state where the rotation direction of the end mill is reversed with respect to the rotation direction of the end mill as described above, the blade of the end mill bites into the bottom surface and cuts so as to scoop the bottom surface. Cutting resistance upward in the direction of the rotation axis of the end mill acts on the end mill. In particular, when cutting the bottom surface of the peripheral portion of the through hole, the blade portion cuts the bottom surface so that the blade portion of the end mill always scoops the edge portion which is the hole edge of the through hole, so that the end mill is upward in the rotation axis direction. Cutting resistance will act more. In this way, if the blade portion cuts the bottom surface while the cutting resistance upward in the rotation axis direction of the end mill acts, the bottom surface is cut while being lifted by the blade portion, and as a result, the bottom surface is cut too deeply. Further, after the recess is machined, the bottom wall portion bends toward the side opposite to the opening of the recess due to the elimination of the upward cutting resistance acting in the direction of the rotation axis at the time of machining. Therefore, there is a problem that it is difficult to secure the flatness of the bottom surface necessary for obtaining the sealing property of the hydraulic oil chamber. This problem becomes more remarkable as the bottom wall portion of the recess is formed thinner and the diameter of the through hole is larger.

Further, in order to suppress the upward cutting resistance acting on the end mill in the direction of the rotation axis, it is conceivable that the direction in which the end mill is rotated is the same as the rotation direction of the end mill. However, if this is done, the side surface will be cut by an upcut when the side surface of the concave portion is machined, and there is a risk that the tool life of the end mill will be shortened.

The present invention has been devised in view of the conventional circumstances, and is a surface treatment of a member having a through hole in the recess, which can improve the tool life of the end mill while ensuring the flatness of the bottom surface of the recess. One purpose is to provide methods and the like.

As one of the preferred embodiments of the present invention, the peripheral portion of the through hole provided in the recess is provided so that the rotation direction of the end mill and the direction in which the end mill is relatively rotated around the through hole are in the same direction. The side surface of the recess is machined so that the direction of rotation of the end mill and the direction of relatively orbiting the end mill around the through hole are opposite to each other.

According to a preferred embodiment of the present invention, the tool life of the end mill can be improved while ensuring the flatness of the bottom surface of the recess.

It is a side view which shows the oil pump in a state attached to the engine block of an internal combustion engine. It is sectional drawing which showed the oil pump which cut along the line AA of FIG. 1 in the state which attached the front cover. It is sectional drawing of the oil pump before the cam ring swings. It is sectional drawing of the oil pump after the cam ring swings. It is a front view of a housing. It is a rear view of a housing. It is sectional drawing of the housing cut along the line BB of FIG. (A) is an explanatory diagram showing stepwise the positional relationship between the end mill and the work material when the upper surface of the work material is cut by up-cut using the end mill, and (b) is the line of (a). It is sectional drawing of the end mill and the work material cut along CC. (A) is an explanatory diagram showing stepwise the positional relationship between the end mill and the work material when the upper surface of the work material is cut by downcut using the end mill, and (b) is the line of (a). It is sectional drawing of the end mill and the work material cut along DD. It is a perspective view which showed the positional relationship between an end mill and a work material when the side surface of a work material is cut by up-cut using an end mill. It is a perspective view which showed the positional relationship between an end mill and a work material when the side surface of a work material is cut by a down cut using an end mill. It is a process drawing which shows the rough processing process of the bottom surface, the side surface, the opening end surface, etc. of a housing. It is a process drawing which shows the finishing process of the contact surface of a housing. It is a process drawing which shows the finishing process of the bottom surface, the side surface, the opening end surface, etc. of a housing. It is a process drawing which shows the finishing process of the surface processing method of the prior art of the concave part of a housing. It is sectional drawing of the housing or the like which shows the solution method of another problem of this embodiment.

Hereinafter, an embodiment of the oil pump of the present invention will be described with reference to the drawings.

[Oil pump configuration]
FIG. 1 is a side view showing an oil pump 1 attached to an engine block 3 of an internal combustion engine. FIG. 2 is a cross-sectional view showing a state in which an oil pump 1 or the like cut along the line AA of FIG. 1 is attached to the front cover 4.

The oil pump 1 is configured as a variable capacity type oil pump, and is driven to rotate by a rotational force transmitted from the crankshaft 2, so that various sliding parts in an internal combustion engine, a valve timing control device, and the like are used. It supplies oil (lubricating oil) to equipment. The oil pump 1 is housed in a pump housing portion 5 provided between the engine block 3 and the front cover 4. The oil pump 1 has a housing 6 in which one end side in the axial direction of the crankshaft 2 is open and the other end side is closed, a pump structure 7 housed in the housing 6, and a housing housed in the pump structure 7. A cover 8 for closing the opening 9 of 6 is provided.

The housing 6 is formed in a concave shape by die-casting using a metal material, for example, an aluminum alloy material. A recess 6a for accommodating the pump configuration 7 is formed in the end surface of the housing 6 located on the axial end portion 2a side of the crankshaft 2. The recess 6a is formed by finishing the inner surface of the recess 6a by cutting using a first end mill 53 described later. The recess 6a is formed by a bottom wall portion 10 and an annular peripheral wall portion 11 rising from the bottom wall portion 10 so as to be orthogonal to the bottom wall portion 10. A circular through hole 10a that rotatably supports the crankshaft 2 is formed through the bottom wall portion 10 along the rotation axis direction of the crankshaft 2.

The pump structure 7 is mainly composed of a crankshaft 2 which is a rotation shaft, a rotor 12 which is rotationally driven by the crankshaft 2, and a vane 13 and a cam ring 14 which will be described later. The rotor 12 is housed in the recess 6a with the outer peripheral portion of the crankshaft 2 inserted.

Like the housing 6, the cover 8 is made of a metal material, for example an aluminum alloy material, and has a circular insertion hole 7a that rotatably supports the crankshaft 2 at a position corresponding to the through hole 10a of the housing 6. , Eight fixing members, for example, bolts 17, are attached and fixed to the housing 6. Further, the cover 8 is attached and fixed to the engine block 3 together with the housing 6 by holding four fixing members, for example, bolts 18.

FIG. 3 is a cross-sectional view of the oil pump 1 before the cam ring 14 swings. FIG. 4 is a cross-sectional view of the oil pump 1 after the cam ring 14 swings.

The pump structure 7 is composed of a crankshaft 2 which is a rotating shaft, a rotor 12 assembled on the outer peripheral portion of the crankshaft 2, a vane 13, a cam ring 14, a coil spring 15, and the like. In the pump configuration 7, when the rotor 12 rotates integrally with the crankshaft 2, the volumes of the plurality of hydraulic oil chambers 21 change, and the oil, which is the fluid sucked from the suction portion, is discharged from the discharge portion. ..

As shown in FIGS. 3 and 4, the rotor 12 is fitted in the outer peripheral portion of the crankshaft 2 rotatably provided in the center of the recess 6a in a state where relative rotation is restricted, and is housed in the recess 6a. Has been done. Further, on the outer peripheral side of the rotor 12, nine slits 19 extending radially outward from the inner center side of the rotor 12 are formed at equidistant positions in the circumferential direction of the rotor 12, and in each slit 19, the slits 19 are formed. A thin plate-shaped vane 13 made of metal is arranged so as to be infested. Further, a cam ring 14 which is a swinging member that can swing around the pivot pin 20 is provided between the outer peripheral surface of the rotor 12 and the inner peripheral surface of the housing 6. That is, the tip surface of the vane 13 is in sliding contact with the inner peripheral surface of the cam ring 14, so that the rotor 12, the two vanes 13 facing the circumferential direction of the rotor 12, the cam ring 14, the housing 6, and the cover 8 are in sliding contact with each other. The space surrounded by and becomes the hydraulic oil chamber 21.

Further, in the housing 6, an urging member compressed by a predetermined set load Ws, for example, a coil spring 15 is provided on one side of the arm portion 14a protruding from the cam ring 14 at a portion facing the pivot pin 20. It is arranged so that it can be elastically contacted.

Further, in the outer peripheral region of the cam ring 14, a pair of first and second control oil chambers 25 and 26 are provided by the pivot pin 20 and the first and second sealing members 23 and 24 provided on the outer peripheral portion of the cam ring 14. It is defined.

Hydraulic pressure is guided to the first control oil chamber 25 from the main oil gallery of the internal combustion engine to which the oil discharged from the discharge port formed in the bottom wall portion 10 is supplied. As a result, the first pressure receiving surface 14b formed by the outer peripheral surface of the cam ring 14 facing the first control oil chamber 25 receives the hydraulic pressure from the discharge port and resists the urging force of the coil spring 15 of the cam ring 14. A swinging force (moving force) is applied in the direction of reducing the amount of eccentricity (counterclockwise in FIGS. 3 and 4).

On the other hand, in the second control oil chamber 26 as well, the hydraulic pressure from the main oil gallery is appropriately introduced by turning on and off the electromagnetic switching valve 27. The second pressure receiving surface 14c formed by the outer peripheral surface of the cam ring 14 facing the second control oil chamber 26 receives the discharge pressure and increases the eccentricity of the cam ring 14 (clockwise in FIGS. 3 and 4). Swinging force (moving force) is applied.

The oil pump 1 changes from the state before the cam ring 14 shown in FIG. 3 to FIG. 4 by turning the exciting current supplied from the control unit for controlling the internal combustion engine to the electromagnetic switching valve 27 from on to off. It is switched to the state after the swing of the cam ring 14 shown.

[Housing structure]
FIG. 5 is a front view of the housing 6.

The recess 6a of the housing 6 is relatively thin, and has a bottom wall portion 10 formed in a substantially circular plate shape and a substantially annular peripheral wall portion that rises from the outer edge of the bottom wall portion 10 and surrounds the bottom wall portion 10. 11 and. The bottom wall portion 10 has a bottom surface 28 which is a surface of the recess 6a on the opening 9 side, and a relatively large-diameter circle in which the crankshaft 2 is rotatably inserted at a substantially central position of the bottom surface 28. A through hole 10a having a shape is formed through. The surface area of the bottom surface 28 is larger than the outer diameter of the cam ring 14 in order to secure the region where the cam ring 14 swings. The bottom surface 28 is connected to the side surface 11a, which is a surface on the inner peripheral side of the peripheral wall portion 11 orthogonal to the bottom surface 28. The bottom surface 28 and the side surface 11a are formed by finishing by cutting using a first end mill 53 described later.

Here, for convenience of the following description, it is a portion of the bottom surface 28 around the through hole 10a, and is substantially at the center between the edge portion of the through hole 10a and the side surface 11a of the peripheral wall portion 11 in the radial direction of the through hole 10a. When the position is indicated by the broken line circle 29 in FIG. 5, the annular region from the edge portion of the through hole 10a to the circle 29 is defined as the “peripheral portion 30”. Further, the annular region of the bottom surface 28 adjacent to the peripheral wall portion 11 from the circle 29 to the side surface 11a of the peripheral wall portion 11 is defined as the “peripheral wall portion adjacent portion 31”. In addition, in order to simplify FIG. 5, the circle 29 has a shape when the unevenness of the spring accommodating chamber 22 or the like in the recess 6a is omitted and the inner circumference of the recess 6a is drawn as a circle. ..

Since the peripheral wall portion adjacent portion 31 is continuous with the peripheral wall portion 11, it is a portion having higher rigidity than the peripheral portion 30 adjacent to the through hole 10a.

The outer peripheral portion of the peripheral wall portion 11 has nine boss portions 33a to 33i formed so as to project outward in the radial direction of the through hole 10a. Further, a flat opening end surface 32 surrounding the opening 9 of the recess 6a is formed at the tip of the peripheral wall portion 11. The open end surface 32 is a contact surface that comes into contact with the cover 8 when the cover 8 is attached to the housing 6. The open end face 32 is formed by finishing by cutting using a first face mill 55 described later. At the positions corresponding to the six boss portions 33a, 33c, 33e, 33f, 33h, 33i of the opening end surface 32, there are six female screw holes 34 to which the bolts 17 are screwed when the cover 8 is attached to the housing 6. It is formed. Further, at the positions corresponding to the two boss portions 33b and 33d of the opening end surface 32, the two bolt insertion holes (mounting portions) 35 into which the bolts 18 are inserted when the housing 6 is attached to the engine block 3 together with the cover 8. Are formed through each. Further, a circular knock pin hole 36 is formed at a position of the opening end surface 32 corresponding to the boss portion 33 g so as to be positioned with the cover 8 when the cover 8 is attached to the housing 6.

Further, an overhanging portion 38 is formed in a part of the outer peripheral portion of the peripheral wall portion 11 so as to project outward in the radial direction of the through hole 10a from the outer peripheral portion. The outer peripheral portion of the overhanging portion 38 has three boss portions 33j, 33k, 33m formed so as to project outward in the radial direction of the through hole 10a. The overhanging portion 38 has a flat surface 38a that is on the same plane as the opening end surface 32 and is continuous with the opening end surface 32. The surface 38a is formed by finishing by cutting using a face mill 55, which will be described later, as a series of processing when processing the open end surface 32. A female screw hole 34 is formed in the surface 38a near the region between the boss portions 33j and 33k and at a position corresponding to the boss portion 33m to which the bolt 17 is screwed when the cover 8 is attached to the housing 6. .. Further, at positions corresponding to the two boss portions 33j and 33k on the surface 38a, there are two bolt insertion holes (mounting portions) 35 into which bolts 18 are inserted when the housing 6 is attached to the engine block 3 together with the cover 8. Each is formed.

The housing 6 is clamped at a position adjacent to the boss portions 33d, 33h, 33k on the outer peripheral surfaces of the peripheral wall portion 11 and the overhanging portion 38 when the bottom surface 28, the side surface 11a, and the opening end surface 32 of the recess 6a are machined. Two clamp seats 37 are formed so as to project. Each clamp seat 37 has a substantially triangular plate shape, and is formed at a position offset from the opening end surface 32 toward the through hole 10a in the through direction of the through hole 10a. The clamp seat 37 has a surface 37b, which will be described later, which is a reference surface for processing the bottom surface 28, the side surface 11a, and the opening end surface 32.

FIG. 6 is a rear view of the housing 6.

The side opposite to the opening 9 of the housing 6, more specifically, the back side of the bottom surface 28 of the bottom wall portion 10 is in contact with the engine block 3 which is a mating member when attached to the internal combustion engine. 1 Contact surface 39 is formed. As shown in FIG. 6, the first contact surface 39 is continuous in a semicircular shape along the circumferential direction of the through hole 10a at a position near the boss portion 33a of the bottom wall portion 10. Further, the surface 40 of the boss portion 33d provided at a position separated from the first contact surface 39 is on the same plane as the first contact surface 39, and comes into contact with the engine block 3 when attached to the engine block 3. It becomes the first contact surface. The first contact surface 39 and the surface 40 are formed by finishing by cutting using a first face mill 55 described later.

Further, the portion located at the tip of the overhanging portion 38, that is, the portion of the overhanging portion 38 that is most distant from the first contact surface 39 in the radial direction of the through hole 10a is on the same plane as the first contact surface 39. There is a second contact surface 41 that comes into contact with the engine block 3 when attached to an internal combustion engine. The second contact surface 41 is formed by finishing by cutting using a first face mill 55, which will be described later, as a series of processing when processing the first contact surface 39.

The overhanging portion 38 between the first contact surface 39 and the second contact surface 41 is located on the opening 9 side with respect to the first and second contact surfaces 39 and 41 in order to reduce the weight of the housing 6. Eight recessed meat stealing portions 42a to 42h are provided.

Further, the portions of the unprocessed housing 6 other than the first and second contact surfaces 39 and 41 and the surfaces 40, for example, adjacent to the meat stealing portions 42a to 42h and the boss portions 33d and 33h, are adjacent to the first and second contact surfaces. The cast surface surface formed by aluminum die casting is left in the recessed portions 43 and 44 recessed on the opening 9 side with respect to the surfaces 39 and 41. The meat stealing portion 42a adjacent to the boss portion 33m and the recessed portions 43 and 44 are portions to be clamped during the finishing process of the first and second contact surfaces 39 and 41, which will be described later. In addition, the parts having the cast surface other than the meat stealing portion 42a and the recessed portions 43 and 44 can also be the portions to be clamped during the finishing process of the first and second contact surfaces 39 and 41.

FIG. 7 is a cross-sectional view of the housing 6 cut along line BB of FIG.

As shown in FIG. 7, a groove portion 45 for avoiding interference with the stepped portion 2b (see FIG. 2) provided on the crankshaft 2 is provided at a portion between the through hole 10a and the first contact surface 39. 1 A recess is formed from the contact surface 39 to the recess 6a side.

[Upcut on the bottom]
FIG. 8A is an explanatory view showing stepwise the positional relationship between the end mill 46 and the work material 47 when the upper surface 47a of the work material 47 is machined by up-cutting using the end mill 46, FIG. 8 (a). b) is a cross-sectional view of the end mill 46 and the work material 47 cut along the line CC of FIG. 8 (a). In FIG. 8B, the cross-sectional hatching of the spiral portion of the end mill 46 is omitted.

The following is the upper surface of the work material 47 formed in the shape of a rectangular plate as an example for explaining the upcut when the bottom surface 28 of the bottom wall portion 10 described above is processed by using the end mill 46. A case where the upper surface 47a is processed will be described.

The vertical axis 48 shown in FIG. 8A shows a machining locus drawn by the rotation axis O of the end mill 46 when the end mill 46 cuts the work material 47. The rotation direction P of the end mill 46 is a clockwise direction in FIG. 8A, and the feed direction Q of the end mill 46 is a direction from the lower side to the upper side in FIG. 8A. As shown in FIG. 8A, the end mill 46 is arranged on the vertical axis 48, while the work material 47 is on the right side of the vertical axis 48 when viewed from the feed direction Q of the end mill 46. That is, it is arranged on the right side of the rotation axis O of the end mill 46.

The end mill 46 has a plurality of (four in this embodiment) blade portions 46a due to the spiral shape formed at the tip thereof. The four blade portions 46a are provided at equidistant positions in the rotation direction P of the end mill 46.

The work material 47 is formed in a rectangular plate shape, and has an edge portion 47b facing the end mill 46 in the direction of the vertical axis 48.

In the first step from the bottom of FIG. 8A, the tip surface 46b of the end mill 46 shown in FIG. 8B is located between the upper surface 47a and the lower surface 47c of the work material 47, and the blade portion 46a is the work material. The state before cutting the upper surface 47a of 47 is shown. When the end mill 46 is fed in the feed direction Q from this first stage state, as shown in the second stage from the bottom of FIG. 8A, one blade portion 46a faces the vertical axis 48 of the work material 47. From the cutting start point 49 on the vertical side portion 47d of the above, the edge portion 47b of the work material 47 is scooped into the edge portion 47b. After the blade portion 46a cuts the edge portion 47b, a new edge portion 47b is formed at a position adjacent to the cut edge portion 47b and the feed direction Q of the end mill 46. Then, as shown in the third step from the bottom of FIG. 8A, the upper surface 47a is cut while sequentially scooping the edge portion 47b. At this time, the edge portion 47b scooped by the blade portion 46a is discharged as chips (shown by a broken line in FIG. 8B) while being lifted diagonally upward as shown by the arrow R in FIG. 8B. .. Therefore, the cutting resistance (arrow S in FIG. 8B) upward in the rotation axis direction of the end mill 46 acts on the end mill 46 with the force generated when the edge portion 47b is lifted.

As described above, when the end mill 46 rotates in the clockwise direction and the work material 47 is on the right side of the rotation axis O of the end mill 46 with respect to the feed direction Q of the end mill 46, the end mill 46 faces upward. The cutting process in which the blade portion 46a sequentially scoops the edge portion 47b of the work material 47 while receiving the cutting resistance is defined as "upcut" of the upper surface (bottom surface) 47a. In cutting the upper surface 47a in the upcut, the tool life of the end mill 46 is shorter than in the case where the end mill 46 cuts the upper surface 47a in the downcut described later.

[Down cut on the bottom]
9 (a) is an explanatory view showing stepwise the positional relationship between the end mill 46 and the work material 47 when the upper surface 47 a of the work material 47 is cut by downcut using the end mill 46, FIG. 9 (a). b) is a cross-sectional view of the end mill 46 and the work material 47 cut along the line DD of FIG. 9 (a). Also in FIG. 9B, the cross-sectional hatching of the spiral portion of the end mill 46 is omitted.

Below, as an example for explaining the downcut when the bottom surface 28 of the bottom wall portion 10 is machined by using the end mill 46, the upper surface 47a which is the upper surface of the work material 47 formed in the shape of a rectangular plate. The case of processing is described.

In FIG. 9A, the end mill 46 is arranged on the vertical axis 48, while the work material 47 is on the left side of the vertical axis 48 when viewed from the feed direction Q of the end mill 46, that is, the end mill 46. It is arranged on the left side of the rotation axis O of. The rotation direction P of the end mill 46 is the clockwise direction in FIG. 9A.

In the first step from the bottom of FIG. 9A, the tip surface 46b of the end mill 46 shown in FIG. 9B is located between the upper surface 47a and the lower surface 47c of the work material 47, and the blade portion 46a is the work material. The state before cutting the upper surface 47a of 47 is shown. When the end mill 46 is fed in the feed direction Q from this first stage state, as shown in the second stage from the bottom of FIG. 9A, one blade portion 46a is a work material 47 orthogonal to the vertical axis 48. The cutting start point 50 on the lower lateral side portion 47e bites into the edge portion 47b of the work material 47, and the edge portion 47b is cut. That is, the one blade portion 46a bites into the edge portion 47b of the work material 47 from the cutting start point 50 on the lateral side portion 47e located at the position between the vertical axis 48 and the radius separation of the end mill 46, and the edge portion 47b is formed. To cut. After that, the end mill 46 is further fed in the feed direction Q, and as shown in the third stage from the bottom of FIG. 9A, the next blade portion 46a is offset from the cutting start point 50 to the feed direction Q of the end mill 46. The work material 47 is cut at this position. Then, when this cutting is repeated in sequence, as shown in the fourth step from the bottom of FIG. 9A, the blade portion 46a is separated from the vertical axis 48 by the radius of the end mill 46 and is parallel to the vertical axis 48. A flat surface 51 is cut. The blade portion 46a obtained by cutting the flat surface 51 cuts the arcuate portion 52 shown by the arc-shaped broken line in FIG. 9A between the flat surface 51 and the vertical side portion 47f, and exits to the vertical side portion 47f. At this time, the arc portion 52 cut by the blade portion 46a is discharged as chips (shown by the broken line in FIG. 9B) while being pushed down as shown by the arrow T in FIG. 9B. Therefore, the cutting resistance (arrow U in FIG. 9B) downward in the direction of the rotation axis of the end mill 46 acts on the end mill 46 along with the force when pushing down the arc portion 52.

As described above, when the end mill 46 rotates in the clockwise direction and the work material 47 is on the left side of the rotation axis O of the end mill 46 with respect to the feed direction Q of the end mill 46, the end mill 46 faces downward. The cutting process performed while the blade portion 46a sequentially pushes down the arc portion 52 of the work material 47 while receiving the cutting resistance is defined as “downcut” of the upper surface (bottom surface) 47a. In the cutting of the upper surface 47a in the down cut, since the smooth arc portion 52 is cut after cutting the flat surface 51, the end mill 46 is compared with the cutting in the up cut in which the edge portion 47b where the blade portion 46a easily bites is always scooped. Tool life is extended.

[Side up cut]
FIG. 10 is a perspective view showing the positional relationship between the end mill 46 and the work material 47 when the side surface 47 g of the work material 47 is machined by up-cutting using the end mill 46.

Hereinafter, as an example for explaining the upcut when processing the side surface 11a of the peripheral wall portion 11 described above using the end mill 46, a case where the side surface 47 g of the block-shaped work material 47 is processed will be described.

In FIG. 10, the rotation direction P of the end mill 46 is the clockwise direction of FIG. 10, and the feed direction Q of the end mill 46 is a direction from the lower side of FIG. 10 toward the diagonally upper right side. As shown in FIG. 10, the work material 47 is arranged on the left side of the rotation axis O of the end mill 46 when viewed from the feed direction Q of the end mill 46. When the side surface 47g of the work material 47 arranged in this way is cut by the end mill 46, the side surface 47g is cut so that the cutting edge portion 46c of the end mill 46 is constantly pressed against the side surface 47g and bites into the side surface 47g.

As described above, when the end mill 46 rotates in the clockwise direction and the work material 47 is on the left side of the rotation axis O of the end mill 46 with respect to the feed direction Q of the end mill 46, the cutting edge portion of the end mill 46 The cutting process in which the 46c is constantly pressed against the side surface 47g and bites into the side surface 47g is defined as an "upcut" of the side surface 47g. In cutting the side surface 47g in the upcut, the side surface 47g is cut while the cutting edge portion 46c is constantly pressed against the side surface 47g, so that the cutting edge portion 46c of the end mill 46 is easily worn, and the tool of the end mill 46 in the downcut described later It will be shorter than the life.

[Side down cut]
FIG. 11 is a perspective view showing the positional relationship between the end mill 46 and the work material 47 when the side surface 47 g of the work material 47 is cut by downcut using the end mill 46.

In FIG. 11, the rotation direction P of the end mill 46 is the clockwise direction of FIG. 11, and the feed direction Q of the end mill 46 is a direction from the lower side of FIG. 11 toward the diagonally upper left side. As shown in FIG. 11, the work material 47 is arranged on the right side of the rotation axis O of the end mill 46 when viewed from the feed direction Q of the end mill 46. When the side surface 47g of the work material 47 arranged in this way is cut by the end mill 46, the cutting edge portion 46c of the end mill 46 cuts the side surface 47g so as to always escape from the side surface 47g.

As described above, when the end mill 46 rotates in the clockwise direction and the work material 47 is on the right side of the rotation axis O of the end mill 46 with respect to the feed direction Q of the end mill 46, the cutting edge portion of the end mill 46 The cutting process performed by the 46c while constantly escaping from the side surface 47 g is defined as a "down cut" of the side surface 47 g. In the cutting of the side surface 47g in the down cut, the contact of the cutting edge portion 46c with the side surface 47g is weaker than in the cutting in the up cut, so that the cutting edge portion 46c is less likely to be worn. Therefore, the tool life of the end mill 46 in the down cut is longer than the tool life of the end mill 46 in the up cut.

[Manufacturing method of oil pump]
FIG. 12 is a process diagram showing a roughing process of the bottom surface 28, the side surface 11a, the opening end surface 32, and the like of the housing 6, which is one of the various processes of the manufacturing method of the oil pump 1. FIG. 13 is a process diagram showing one of various processes of the manufacturing method of the oil pump 1 and a finishing process of the first and second contact surfaces 39 and 41 of the housing 6. FIG. 14 is a process diagram showing one of various processes of the manufacturing method of the oil pump 1 and a finishing process of the bottom surface 28, the side surface 11a, the opening end surface 32, and the like of the housing 6. The lower side of FIGS. 12 and 14 shows a plan view of the housing 6 when viewed from the opening 9 side, while the lower side of FIG. 13 shows a rear view of the housing 6. Further, on the upper side of FIGS. 12 to 14, a schematic cross-sectional view of the housing 6 cut along the radial direction of the through hole 10a is shown. Further, in FIGS. 12 to 14, the rotation direction P of the first end mill 53, the second face mill 54, and the first face mill 55 shown by virtual lines is a clockwise direction.

First, a housing 6 which is a material formed by die-casting aluminum is prepared, and a relatively large-diameter through hole 10a is formed through the center of the bottom wall portion 10 using a drilling tool, for example, a drill. back. Further, a first positioning hole 57 into which the first positioning pin 56 for positioning is inserted is formed through at a predetermined position on the opening end surface 32 of the housing 6. Further, a second positioning hole 59 into which the second positioning pin 58 for positioning is inserted is formed through the overhanging portion 38 at a predetermined position. The first and second positioning pins 56 and 58 are formed as rod-shaped positioning pins having a truncated cone-shaped positioning portion 60 at the tip thereof. After forming the through holes 10a and the first and second positioning holes 57 and 59 in the housing 6, the surface of the housing 6 other than the inner peripheral surface such as the through holes 10a becomes a cast surface formed by aluminum die casting. ing.

Next, in the roughing process of the bottom surface 28 of the housing 6 shown in FIG. 12, the housing 6 which is a member having the through hole 10a in the bottom wall portion 10 is not shown in a posture in which the opening 9 faces upward. Install inside. When the housing 6 is installed, the housing 6 is positioned on the processing equipment via the first and second positioning pins 56 and 58 inserted into the first and second positioning holes 57 and 59. For example, in a state where the first positioning pin 56 is inserted into the first positioning hole 57, the positioning of the first positioning pin 56 is shown in the frame 61 as a cross-sectional view cut along the line EE of FIG. The tip portion 60a of the portion 60 is arranged in the first positioning hole 57, and the inclined portion 60b of the positioning portion 60 is in contact with the lower edge portion of the first positioning hole 57.

After the housing 6 is installed, the clamp seats 37 formed at predetermined three locations on the outer peripheral portion of the housing 6 and having the cast surface surface are clamped by using the clamping device 62. The clamp device 62 is provided so as to be rotatable around a support pin 63, and is provided with respect to a rectangular plate-shaped pressing portion 64 that presses the surface 37a on the opening end surface 32 side of the clamp seat 37, and the pressing portion 64. It has a clamp pin 65 that presses the surface 37b of the clamp seat 37 on the side opposite to the opening end surface 32. The clamp pin 65 has a shaft portion 65a and a truncated cone-shaped end portion 65b formed integrally with one end portion of the shaft portion 65a. Further, the pressing force of the clamp pin 65 is appropriately adjusted by the air pressure supplied from an air supply source (not shown). The tip of the conical trapezoidal end portion 65b has a circular contact surface 65c capable of contacting the surface 37b of the clamp seat 37 and having an outer diameter smaller than that of the shaft portion 65a. When the clamp device 62 clamps the clamp seat 37, the contact surface 65c of the conical trapezoidal end portion 65b is a holding portion as shown in the frame 70 as a cross-sectional view cut along the line FF in FIG. The peripheral wall portion 11 is pressed against 64. In this state, stress acts appropriately on the housing 6, and the bending of the bottom wall portion 10 is suppressed. In this way, the roughing process of FIG. 12 is performed using the surface 37b, which is the casting surface, as a processing certificate.

After clamping each clamp seat 37, the first and second positioning pins 56 and 58 are removed from the first and second positioning holes 57 and 59.

Next, a drilling tool, such as a drill, is used to machine the knock pin hole 36 and the pivot pin hole (circular recess) 66 into rough holes with relatively large dimensional tolerances. Further, in preparation for the insertion of the third and fourth positioning pins 67 and 68 in the post-process described later, the first and second positioning holes 57 and 59 are finished by using a drill.

After machining the knock pin hole 36 and the like, the peripheral portion 30 which is the portion of the bottom surface 28 around the through hole 10a is roughly machined to a predetermined cutting depth by using the first end mill 53 shown by the virtual line in FIG. .. During this roughing, from the inside of the through hole 10a so that the rotation direction P of the first end mill 53 and the direction in which the first end mill 53 is relatively orbited around the through hole 10a are the same direction. The peripheral portion 30 is roughly machined by rotating the first end mill 53. That is, the first is to orbit the peripheral portion 30 in the clockwise direction of FIG. 12 (feeding direction of the first end mill 53 indicated by reference numeral V in FIG. 12) with respect to the housing 6 fixed by the three clamping devices 62. By moving the end mill 53, the peripheral portion 30 is roughly machined. At this time, the peripheral portion 30 is always on the left side with respect to the rotation axis O1 of the first end mill 53, and the first end mill 53 rough-processes the peripheral portion 30 by down-cutting (FIGS. 9A and 9B). )reference).

After the peripheral portion 30 is roughly rounded by the first end mill 53, as a series of rough machining, the peripheral wall portion adjacent portion 31 which is the portion of the bottom surface 28 adjacent to the peripheral wall portion 11 and the peripheral wall portion 11 The side surface 11a and the side surface 11a are roughly machined at the same time with a predetermined cutting depth. At the time of this roughing, the peripheral wall portion adjacent portion 31 and the peripheral wall portion adjacent portion 31 and the direction in which the rotation direction P of the first end mill 53 is relatively rotated around the through hole 10a are opposite to each other. The side surface 11a is roughly processed. That is, the feed direction of the first end mill 53, which has been orbiting in the clockwise direction, is reversed, and the direction is counterclockwise with respect to the housing 6 fixed by the three clamping devices 62 (indicated by reference numeral W in FIG. 12). By moving the first end mill 53 so as to orbit in the feed direction of the first end mill 53), the peripheral wall portion adjacent portion 31 and the side surface 11a are roughly machined. At this time, the peripheral wall portion adjacent portion 31 is always on the right side with respect to the rotation axis O1 of the first end mill 53, and the first end mill 53 rough-processes the peripheral wall portion adjacent portion 31 by up-cutting (FIG. 8A). See FIG. 8 (b)). Further, the side surface 11a is always on the right side with respect to the rotation axis O1 of the first end mill 53, and the first end mill 53 rough-processes the side surface 11a by down-cutting (see FIG. 11).

Next, using a second face mill 54 (shown by a virtual line in FIG. 12) having an outer diameter larger than that of the first end mill 53, the open end surface 32 and the overhanging portion 38 of the housing 6 to be the mating surface with the cover 8 are used. Surface 38a is rough-processed. During this rough machining, the second face mill 54 is moved from the diagonally lower left side of the housing 6 to the overhanging portion 38 side as shown in the feed direction indicated by reference numeral X in FIG. 12, and then the second face mill 54 is used. The opening end surface 32 and the surface 38a are roughly machined so that the feeding direction of 54 is folded back and returned to the opening 9 side.

Next, in the finishing process of the first and second contact surfaces 39 and 41 of the housing 6 shown in FIG. 13, which is a post-process of the roughing process of the bottom surface 28 of the housing 6, the processing equipment is different from that of FIG. The housing 6 is installed in the processing equipment of the above in a posture in which the opening 9 faces downward. When installing the housing 6, the housing 6 is positioned on the processing equipment via the cylindrical third and fourth positioning pins 67 and 68 inserted into the first and second positioning holes 57 and 59.

After the housing 6 is installed, instead of the above three clamp seats 37, the three clamp portions having the cast surface surface provided at predetermined positions on the outer peripheral portion of the housing 6, that is, the meat stealing portion 42a and the recessed portions 43, 44 ( (See FIG. 6) is clamped using each clamping device 62. In the finishing processing step of FIG. 13, the casting surface on the side opposite to the opening end surface 32 of the meat stealing portion 42a and the recessed portions 43 and 44 to which the contact surface 65c of the clamp pin 65 abuts becomes the processing certificate.

Next, using the first face mill 55, the first and second contact surfaces 39 and 41 are roughly machined to a predetermined depth of cut. During this rough machining, the first face mill 55 is moved from the left side of the first positioning hole 57 to the overhanging portion 38 side as shown in the feed direction indicated by reference numeral Y in FIG. , The second contact surfaces 39 and 41 are roughly machined.

After the roughing process of the first and second contact surfaces 39 and 41, the knock pin hole 36 and the pivot pin hole 66 are machined into rough holes having a smaller dimensional tolerance than the roughing process of FIG.

After machining the knock pin hole 36 and the pivot pin hole 66, the first face mill 55 is used to finish the first and second contact surfaces 39 and 41 at a predetermined cutting depth. During this finishing process, the first face mill 55 is moved in the same feed direction Y as in the rough processing of the first and second contact surfaces 39 and 41.

After finishing the first and second contact surfaces 39 and 41, for example, a first end mill 53 is used to flatten the surface 37b having the casting surface on the first and second contact surfaces 39 and 41 side of the clamp seat 37. Finish the surface. As a result, the first and second contact surfaces 39 and 41 and the surface 37b become parallel.

Next, in the finishing process of the bottom surface 28 and the like of the housing 6 shown in FIG. 14, which is a post-process of the finishing process of the first and second contact surfaces 39 and 41 of the housing 6, the processing equipment of FIGS. 12 and 13 is used. Installes the housing 6 in a different processing facility with the opening 9 facing up. When the housing 6 is installed, the housing 6 is positioned on the processing equipment via the third and fourth positioning pins 67 and 68 inserted into the first and second positioning holes 57 and 59.

After the housing 6 is installed, each clamp seat 37 is clamped using each clamp device 62. In the process of FIG. 13, the flat surface 37b formed in the finishing process of the first and second contact surfaces 39 and 41 serves as a processing certificate.

After clamping each clamp seat 37, a drill is used to finish the knock pin hole 36 and the pivot pin hole 66 into high-precision holes having a small dimensional tolerance.

Next, the peripheral portion 30 of the bottom surface 28 is finished by using the first end mill 53 at a predetermined cutting depth. During this finishing process, the peripheral portion 30 is oriented in the clockwise direction (feeding direction) of FIG. 14 with respect to the housing 6 fixed by the three clamping devices 62, as in the roughing process of the bottom surface 28 of the housing 6. The first end mill 53 is moved so as to go around V). At this time, the first end mill 53 finish-processes the peripheral portion 30 by down-cutting in the same manner as in the roughing process of the bottom surface 28 of the housing 6 (see FIGS. 9A and 9B).

After the peripheral portion 30 is finished around once by the first end mill 53, the peripheral wall portion adjacent portion 31 and the side surface 11a are simultaneously finished as a series of finishing processes. During this finishing process, the feed direction of the first end mill 53, which has been orbiting in the clockwise direction, is reversed and fixed by the three clamp devices 62, as in the roughing process of the bottom surface 28 of the housing 6. The first end mill 53 is moved so as to orbit in the counterclockwise direction (feeding direction W) with respect to the housing 6. At this time, the first end mill 53 finish-processes the peripheral wall portion adjacent portion 31 by up-cutting in the same manner as in the roughing process of the bottom surface 28 of the housing 6 (see FIGS. 8A and 8B). At the same time, the first end mill 53 finishes the side surface 11a by down-cutting in the same manner as in the roughing process of the bottom surface 28 of the housing 6 (see FIG. 11).

After finishing the peripheral portion 30, the peripheral wall portion adjacent portion 31 and the side surface 11a at a predetermined cutting depth, the peripheral portion 30 and the peripheral wall portion are zero-cut using the first end mill 53 with the same processing trajectory as this finishing processing. The portion adjacent portion 31 and the side surface 11a are finished again. Here, "zero cut" is a cutting process performed at a cutting depth of 0 mm, and removes residual stress generated in the peripheral portion 30, the peripheral wall portion adjacent portion 31 and the side surface 11a during the machining in the previous process. However, it stabilizes the flatness of the peripheral portion 30 and the like.

After the finishing process with the zero cut, the first face mill 55 is used to finish the opening end surface 32 of the housing 6 and the surface 38a of the overhanging portion 38 at a predetermined cutting depth. During this finishing process, the first face mill 55 is moved from the diagonally lower left side of the opening 9 to the overhanging portion 38 side as shown in the feed direction indicated by reference numeral Z in FIG.

The roughing and finishing of the housing 6 are performed while appropriately supplying coolant from a nozzle (not shown) provided in the processing equipment to the peripheral portion 30 and the cutting edge portion of the first end mill 53 and the like. Further, the coolant may be supplied to the peripheral portion 30 or the like through an oil passage provided inside the first end mill 53 or the like.

After finishing the opening end surface 32, a female screw hole 34 (see FIG. 5) for attaching the cover 8 and a bolt insertion hole 35 for attaching to the engine block 3 are provided in the opening end surface 32 and the overhanging portion 38 of the housing 6. (See FIG. 5) is formed using a drill.

Then, the pump structure 7 composed of the rotor 12 and the like is housed in the recess 6a of the housing 6, and the cover 8 is put on the recess 6a to close the opening 9 of the recess 6a. When covering the cover 8, the cover 8 is positioned with respect to the housing 6 via the knock pin press-fitted into the knock pin hole 36 formed in the open end surface 32 of the housing 6 and the pivot pin 20 inserted into the pivot pin hole 66. .. After closing the opening 9, the cover 8 is attached and fixed to the housing 6 by screwing the bolts 17 into the female screw holes 34 of the housing 6 through the bolt through holes formed in the cover 8.

[Effect of this embodiment]
FIG. 15 is a process diagram showing a finishing process of the surface processing method of the prior art of the recess 6a of the housing 6.

In the finishing process of the prior art, in consideration of extending the tool life of the end mill 46 by cutting the side surface 11a with a down cut when machining the side surface 11a of the peripheral wall portion 11, the rotation direction P of the end mill 46 is set. On the other hand, the bottom surface 28 and the side surface 11a were machined so that the circumferential direction of the end mill 46 was reversed. That is, the end mill 46 rotating in the rotation direction P is rotated about once in the counterclockwise direction of FIG. 15 from the inside of the through hole 10a as shown by the reference numeral G in FIG. After processing, the peripheral wall portion adjacent portion 31 and the side surface 11a were subsequently processed by making one round in the counterclockwise direction.

However, in such processing in the counterclockwise direction, the side surface 11a can be cut by the down cut, but the peripheral portion 30 and the peripheral wall portion adjacent portion 31 are cut by the up cut. More specifically, the peripheral portion 30 and the peripheral wall portion adjacent portion 31 are always on the right side with respect to the rotation axis O of the end mill 46, and the end mill 46 cuts the peripheral portion 30 and the peripheral wall portion adjacent portion 31 by an upcut (FIG. 8 (a), see FIG. 8 (b)). When cutting with an upcut, the blade portion of the end mill 46 bites into the edge portion so as to scoop the edge portion of the peripheral portion 30 and the peripheral wall portion adjacent portion 31, so that the edge portion scooped by the blade portion is slanted. Lifted upwards. Along with this, the end mill 46 receives cutting resistance upward in the rotation axis direction of the end mill 46, so that the peripheral portion 30 and the peripheral wall portion adjacent portion 31 are lifted while cutting. Then, when the end mill 46 is separated from the housing 6 after cutting the peripheral portion 30 and the peripheral wall portion adjacent portion 31, the bottom wall portion 10 made of an aluminum alloy material returns and deforms due to the reaction force of the cutting resistance upward in the direction of the rotation axis. , It bends toward the side opposite to the opening 9. As a result, an appropriate flatness of the bottom surface 28 of the recess 6a cannot be ensured, and there is a possibility that the sealing property of the hydraulic oil chamber formed inside the housing 6 deteriorates.

Further, when the end mill 46 cuts the peripheral portion 30 by up-cutting, it bites into the edge portion which is the hole edge of the peripheral portion 30 and cuts, so that the amount of wear of the blade portion of the end mill 46 increases and the tool life of the end mill 46 is extended. There was the problem of getting worse.

In contrast to the above-mentioned prior art, in the present embodiment, the rotation direction P of the first end mill 53 and the direction in which the first end mill 53 is relatively orbited around the through hole 10a are the same when processing the peripheral portion 30. The peripheral portion 30 is processed so as to be in the direction. That is, when processing the peripheral portion 30, the peripheral portion 30 is processed by rotating the first end mill 53, which rotates in the clockwise direction, around the through hole 10a in the clockwise direction. As a result, the peripheral portion 30 is always on the left side with respect to the rotation axis O1 of the first end mill 53, and the first end mill 53 processes the peripheral portion 30 by downcutting. At this time, the first end mill 53 cuts the peripheral portion 30 while receiving the cutting resistance downward in the rotation axis direction, but the cutting resistance downward in the rotation axis direction is smaller than the cutting resistance upward in the rotation axis direction in the upcut. Therefore, it is difficult to deform the bottom wall portion 10. Therefore, the bending of the bottom wall portion 10 when the first end mill 53 is detached from the housing 6 is minimized, and an appropriate flatness of the bottom surface 28 can be ensured. Therefore, the sealing property of the hydraulic oil chamber 21 formed inside the housing 6 can be improved.

Further, when the peripheral portion 30 is cut by the down cut, the blade portion of the first end mill 53 cuts the smooth arc portion 52 (see FIG. 9A), so that the amount of wear of the blade portion can be suppressed. Therefore, the tool life of the first end mill 53 can be extended as compared with the up-cut cutting in which the edge portion where the blade portion easily bites is sequentially cut.

Further, in the present embodiment, the side surface 11a of the peripheral wall portion 11 is provided so that the rotation direction P of the first end mill 53 and the direction in which the first end mill 53 is relatively rotated around the through hole 10a are opposite to each other. Process. That is, when processing the side surface 11a, the side surface 11a is processed by rotating the first end mill 53, which rotates in the clockwise direction, around the through hole 10a in the counterclockwise direction. As a result, the first end mill 53 processes the side surface 11a by downcut while the side surface 11a is always on the right side with respect to the rotation axis O1 of the first end mill 53. Therefore, the tool life of the first end mill 53 can be extended as compared with the case where the side surface 11a is machined by up-cutting.

Further, in the present embodiment, at the same time as cutting the side surface 11a of the peripheral wall portion 11, the peripheral wall portion adjacent portion 31 which is a part of the bottom surface 28 is cut by up-cutting. However, since the peripheral wall portion adjacent portion 31 is continuous with the peripheral wall portion 11, it is a portion having higher rigidity than the peripheral portion 30, and the lifting by the blade portion 46a of the first end mill 53 is suppressed. Therefore, the return deformation of the bottom wall portion 10 at the time of detachment of the first end mill 53 is suppressed, and an appropriate flatness of the bottom surface 28 can be ensured. Further, in the machining of the peripheral wall portion adjacent portion 31, unlike the peripheral portion 30, the edge portion of the hole edge of the through hole 10a does not enter from the inside of the through hole 10a and the edge portion of the hole edge of the through hole 10a is not cut from the beginning of the machining. Compared to machining, the first end mill 53 is designed so that an excessive load is not applied. Also from this point, the return deformation of the bottom wall portion 10 is suppressed, and an appropriate flatness of the bottom surface 28 can be ensured.

Further, in the present embodiment, since a plurality of clamp seats 37 on the outer peripheral portion of the housing 6 are clamped, an appropriate stress is applied to the bottom wall portion 10 via the peripheral wall portion 11 by the clamp, and the bottom wall portion 10 is bent. It is possible to cut the bottom surface 28 of the bottom wall portion 10 in the suppressed state. Therefore, the deformation of the bottom wall portion 10 is suppressed, and the flatness of the bottom surface 28 is improved. Thereby, the sealing property of the hydraulic oil chamber 21 can be improved.

Further, in the present embodiment, the bottom surface 28 of the bottom wall portion 10 of the housing 6 is roughly machined before the first contact surface 39 on the back surface side of the housing 6 is machined. When the first contact surface 39 is machined, residual stress is generated in the thin bottom wall portion 10, and the bottom wall portion 10 is easily deformed. In order to suppress the deformation of the bottom wall portion 10, it is necessary to minimize the finishing allowance when cutting the first contact surface 39 and reduce the residual stress generated in the bottom wall portion 10 during cutting. Therefore, by roughing the bottom surface 28 of the bottom wall portion 10 before cutting the first contact surface 39, the finishing allowance when cutting the first contact surface 39 is minimized and the residual stress is reduced. Can be done.

Further, in the present embodiment, the first contact surface 39 is cut by the first face mill 55, and then the bottom surface 28 is finished. That is, after cutting the first contact surface 39 with a small residual stress, the bottom surface 28, which is the final process, is finished. Therefore, even in the finishing process of the bottom surface 28, cutting can be performed with a small residual stress, and deformation of the bottom wall portion 10 can be suppressed.

Further, in the present embodiment, the open end surface 32 of the housing 6, which is the contact surface with the cover 8, is machined after the bottom surface 28 of the bottom wall portion 10 is machined. The bottom surface 28 of the bottom wall portion 10 is formed so as to have a relatively large area in consideration of the swing of the cam ring 14, while the opening end surface 32 has a smaller area than the bottom surface 28. When the bottom surface 28 having a large area is machined, the housing 6 is more likely to be deformed than when the open end face 32 having a small area is machined. If the bottom surface 28 is cut after cutting the opening end surface 32 which is the contact surface with the cover 8, the opening end surface 32 is tilted due to the deformation of the housing 6 due to the processing of the bottom wall portion 10, and the opening end surface 32 is tilted with the cover 8. There is a risk that proper contact cannot be maintained. Therefore, by cutting the bottom surface 28 of the bottom wall portion 10, which is easily deformed, and then cutting the opening end surface 32, high contact accuracy with the cover 8 can be ensured.

Further, the opening end surface 32 is continuous with the surface 38a of the overhanging portion 38 protruding from the peripheral wall portion 11, and the surface 38a is processed as a series of processing of the opening end surface 32. Since it is relatively difficult to process the flatness of the surface 38a of the overhanging portion 38 with high accuracy in addition to the flatness of the opening end surface 32, the bottom surface 28 of the bottom wall portion 10 which is easily deformed. By processing the opening end surface 32 and the surface 38a by a series of processing after the processing of the above, it is possible to secure a high flatness of the surface 38a.

[Another issue of this embodiment]
FIG. 16 is a cross-sectional view of a housing 6 or the like showing a solution to another problem of the present embodiment.

As described above, the peripheral portion 30 of the bottom surface 28 was cut by downcut while the first end mill 53 received the cutting resistance downward in the rotation axis direction. However, due to the cutting resistance downward in the rotation axis direction, FIG. As shown on the upper side of the above, the bottom wall portion 10 may slightly bend toward the side opposite to the opening 9. At this time, as the bottom wall portion 10 bends, the first contact surface 39 of the bottom wall portion 10 also slightly bends toward the side opposite to the opening 9.

Therefore, in order to suppress the bending of the bottom wall portion 10, as shown on the lower side of FIG. 16, the first contact surface 39 of the housing 6 is bent while the pump configuration 7 is housed in the recess 6a. Is pressed against the flat mounting surface 3a of the engine block 3, and the housing 6 is mounted and fixed to the engine block 3 via the bolt 18. As a result, the fastening force of the bolt 18 presses the first contact surface 39 so as to follow the flat mounting surface 3a, and the engine block 3 corrects the bottom wall portion 10. As a result, an appropriate flatness of the bottom surface 28 can be ensured, and the sealing property of the hydraulic oil chamber 21 formed inside the housing 6 can be improved.

In the above embodiment, an example in which the surface of the housing 6 is processed by moving the first end mill 53 or the like to the housing 6 fixed by the clamp seat 37 is disclosed, but the first end mill 53 in the fixed state is disclosed. The surface of the housing 6 may be processed by moving the housing 6 with respect to the above.

As a method for surface-treating a member having a through hole in a recess based on the above-described embodiment, for example, the method described below can be considered.

One aspect of the surface processing method of processing the inner surface of the recess of a member having a through hole in the bottom wall portion of the recess by using an end mill is to place the end mill in the rotation direction of the end mill and around the through hole. The peripheral portion of the through hole is machined so that the direction of relative rotation is the same, and the rotation direction of the end mill and the direction of relatively orbiting the end mill around the through hole are opposite to each other. The side surface of the recess is processed so as to be in the direction.

In a preferred embodiment of the surface processing method, the end mill cuts the peripheral portion while moving so as to orbit the peripheral portion of the through hole.

In another preferred embodiment, in any of the aspects of the surface processing method, the end mill makes one round of the peripheral portion of the through hole, and then reverses the traveling direction in the opposite direction to the side surface side of the recess. Orbit.

Further, as a method for manufacturing an oil pump based on the above-described embodiment, for example, the method described below can be considered.

In the method of manufacturing an oil pump, as one aspect, a housing provided with a recess having a through hole at the bottom is formed of a metal material, and the rotation direction of an end mill for processing the inner surface of the recess and the circumference of the through hole are described. The peripheral portion of the through hole is machined so that the direction in which the end mill is relatively orbited is the same, and the rotation direction of the end mill and the direction in which the end mill is relatively orbited around the through hole. The side surface of the recess is machined so that

In a preferred embodiment of the method for manufacturing an oil pump, when processing the inner surface of the recess, the processing is performed by clamping a plurality of locations on the outer peripheral portion of the housing.

In another preferred embodiment, in any of the aspects of the method of manufacturing the oil pump, the mating member when attached to the mating member on the surface of the housing opposite the opening of the recess. A contact surface is provided, and the contact surface is machined by a face mill, and the bottom surface of the recess is machined by the end mill.

In another preferred embodiment, in any of the aspects of the oil pump manufacturing method, the bottom surface of the recess of the housing is machined before the contact surface is machined.

In another preferred embodiment, in any of the aspects of the oil pump manufacturing method, the contact surface of the housing with the cover is machined after the bottom surface of the recess is machined.

Further, as the oil pump based on the embodiment described above, for example, the one described below can be considered.

As one aspect of the oil pump, a recess having a through hole in the bottom wall into which a drive shaft is inserted and a surface opposite to the opening of the recess are provided on the surface opposite to the opening of the recess, and the oil pump is attached to a member on the other side. A contact surface that comes into contact with the mating side member and a plurality of mounting portions provided on the outer peripheral portion of the contact surface and attached to the mating side member via a fixing member are provided, and the bottom wall portion is the mating side. The fluid sucked from the suction portion is discharged by being rotationally driven by the aluminum alloy housing formed so as to bend toward the member side and the drive shaft arranged in the recess and inserted into the through hole. It includes a pump structure that discharges from the portion, and a cover that is provided with an insertion hole into which the drive shaft is inserted and closes the opening of the recess.

In a preferred embodiment of the oil pump, the fixing member is a bolt and the mounting portion is a bolt insertion hole into which the bolt is inserted.

In another preferred embodiment, in any one of the oil pump embodiments, the pump configuration is such that the volume of the plurality of hydraulic fluid chambers changes due to the rotation of the rotor fixed to the drive shaft to change the volume of the suction unit. The fluid sucked from the pump is discharged from the discharge portion, and the bottom surface of the recess constitutes a part of the hydraulic oil chamber.

In another preferred embodiment, in any of the aspects of the oil pump, the pump structure has a swinging member that can swing in the recess, and by swinging the swinging member, a discharge amount is discharged. Is variable.

1 ... Oil pump, 6 ... Housing, 6a ... Recess, 10 ... Bottom wall, 10a ... Through hole, 11 ... Peripheral wall, 11a ... Side, 28 ... -Bottom surface, 30 ... peripheral portion, 31 ... peripheral wall portion adjacent portion, 32 ... open end surface, 39 ... first contact surface, 41 ... second contact surface, 53 ... first End mill, 54 ... 2nd face mill

Claims (12)

A surface processing method for processing the inner surface of the recess of a member having a through hole in the bottom wall of the recess using an end mill.
The peripheral portion of the through hole is machined so that the rotation direction of the end mill and the direction of relatively orbiting the end mill around the through hole are the same direction.
A member having a through hole in a recess, characterized in that the side surface of the recess is machined so that the rotation direction of the end mill and the direction in which the end mill is relatively orbited around the through hole are opposite to each other. Surface processing method. The method for surface processing a member having a through hole in a recess according to claim 1, wherein the end mill cuts the peripheral portion while moving so as to orbit the peripheral portion of the through hole. The recess according to claim 2, wherein the end mill goes around the peripheral portion of the through hole once, and then reverses the traveling direction in the opposite direction to orbit the side surface side of the recess. A method for surface processing a member having holes. A housing having a recess with a through hole in the bottom wall is molded from a metal material.
The peripheral portion of the through hole is machined so that the rotation direction of the end mill for machining the inner surface of the recess and the direction of relatively orbiting the end mill around the through hole are the same direction.
The side surface of the recess is machined so that the rotation direction of the end mill and the direction of relatively orbiting the end mill around the through hole are opposite to each other.
Assemble the pump structure in the recess,
A method for manufacturing an oil pump, which comprises closing the opening of the recess with a cover. The method for manufacturing an oil pump according to claim 4, wherein when the inner surface of the recess is machined, a plurality of points on the outer peripheral portion of the housing are clamped for machining. A contact surface that comes into contact with the mating member when attached to the mating member is provided on the surface of the housing opposite to the opening of the recess, and the contact surface is provided by a face mill. Machined and
The method for manufacturing an oil pump according to claim 4, wherein the bottom surface of the recess is machined by the end mill. The method for manufacturing an oil pump according to claim 6, wherein the bottom surface of the recess of the housing is machined before the contact surface is machined. The method for manufacturing an oil pump according to claim 4, wherein the contact surface of the housing with the cover is machined after the bottom surface of the recess is machined. A recess having a through hole in the bottom wall into which the drive shaft is inserted, and a contact surface provided on the surface opposite to the opening of the recess and in contact with the mating member when attached to the mating member. And a plurality of mounting portions provided on the outer peripheral portion of the contact surface and attached to the mating side member via a fixing member, and the bottom wall portion is formed so as to bend toward the mating side member side. Aluminum alloy housing and
A pump structure that is arranged in the recess and is rotationally driven by the drive shaft inserted into the through hole to discharge the fluid sucked from the suction portion from the discharge portion.
A cover that is provided with an insertion hole into which the drive shaft is inserted and closes the opening of the recess.
An oil pump characterized by being equipped with. The oil pump according to claim 9, wherein the fixing member is a bolt, and the mounting portion is a bolt insertion hole into which the bolt is inserted. In the pump structure, the volume of the plurality of hydraulic oil chambers changes due to the rotation of the rotor fixed to the drive shaft, and the fluid sucked from the suction portion is discharged from the discharge portion. The oil pump according to claim 10, wherein the bottom surface of the recess constitutes a part of the hydraulic oil chamber. The oil according to claim 11, wherein the pump structure has a swing member capable of swinging in the recess, and the discharge amount can be changed by swinging the swing member. pump.

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