JP3570465B2 - Stator forming method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a stator used for a torque converter of an automatic transmission for an automobile.
[0002]
[Prior art]
Conventionally, as shown in FIG. 6, a stator main body (also referred to as a shell or a stator shell) 1, a blade 2 and an outer ring (also referred to as a core or a stator core) 3 are formed integrally and concentrically with a resin. There is known a stator in which an outer race 4 of a one-way clutch, which is a bracket, is integrally held by insert molding on a peripheral side.
[0003]
The stator main body 1 is formed by integrally forming an annular plate portion 6 at one end in the axial direction of the cylindrical portion 5 or in the vicinity thereof toward the inner circumferential direction, and a plurality of grooves (oil grooves) are formed on the outer end surface 6a of the plate portion 6. ) Are provided radially, and cutouts 8 are provided on the inner peripheral side of the groove 7, respectively.
[0004]
The stator having the above-described configuration is rotatably mounted inside the automatic transmission, and generates a flow of oil inside the transmission by a pump action accompanying rotation of the blades 2. Most of the oil passes through the blades 2. Then, a small amount of oil goes around the inner peripheral side of the plate portion 6 to lubricate the one-way clutch, and a groove portion 7 and a notch portion 8 are formed in the plate portion 6 to guide the latter flow. Is provided.
[0005]
The stator is injection-molded by a disk gate structure mold. As shown in FIGS. 7 to 10, the stator is first molded as a molded product with a disk gate portion 9 and, after molding, has a top shape. The gate portion 9 is cut off to complete the annular body. In FIG. 8, the disk gate portion 9 is hatched so that the outer peripheral shape of the disk gate portion 9 can be easily understood. At the time of molding, the molding material enters the cavity on the outer peripheral side from the sprue through the disk-shaped disk gate as shown by arrows in FIGS. 9 and 10, and flows radially further in the cavity toward the outer peripheral direction.
[0006]
Also, the above-mentioned molded article with the disc gate portion 9 has an opening corresponding to the shape of the notch portion 8 so that the notch portion 8 is formed on the inner peripheral edge of the annular body immediately when the disc gate portion 9 is cut off later. It is molded as having a lightening portion 10 having a shape. In FIG. 8 and FIG. 9, the lightening portion 10 is dotted to facilitate understanding of the arrangement and shape of the lightening portion 10, but is actually a hole penetrating in the axial direction. The reason why the lightening portion 10 is provided at the time of molding is that without this, the outer shape of the disk gate portion 9 is not a simple circular shape but a complicated shape, and the disk gate portion 9 is cut off according to this complicated shape later. This is an extremely troublesome operation (it is not enough to cut off the disk gate portion 9 in a circular shape, but it is necessary to add further steps to cut out the convex portions corresponding to the cutout portions 8 individually). Must). Further, in order to form the lightening portion 10 from the beginning in the molded product with the disk gate portion 9 as described above, a projection is previously set up as a part of the mold in the cavity of the mold.
[0007]
Therefore, as described above, when the molding material entering the cavity from the sprue via the disk gate radially flows in the cavity toward the outer periphery, the flow is once divided into two parts by the projections set in the cavity, After being divided, they merge on the downstream side of the projection, that is, on the outer peripheral side.
[0008]
However, resin-based molding materials such as phenol resins have the property that once they are broken, the combined state of the molecules does not completely return to the state before the break even if they merge later. A portion (weld portion) 11 having relatively weak mechanical strength is formed. As shown in FIG. 9, the weld portion (also referred to as a weld line) 11 is formed to extend linearly in the outer circumferential direction with the notch 8 as a starting point on the inner circumferential side, and is formed just in the groove portion 7. .
[0009]
On the other hand, the groove portion 7 is formed by molding the plate portion 6 thinner than the other portions only. When an internal stress σ is generated in the plate portion 6 due to torsion or post-shrinkage after molding, stress concentration occurs in the groove portion 7. A part (not shown) is formed.
[0010]
Therefore, according to the prior art, the weld portion 11 and the stress concentration portion are both located in the groove portion 7, and stress concentrates on a portion having relatively low strength. There is a problem that the damage occurs.
[0011]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a method of forming a stator in which the strength of a plate portion is improved and breakage such as cracks is less likely to occur in the plate portion.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a method for forming a stator according to claim 1 of the present invention includes an annular plate portion, a notch portion provided on an inner peripheral edge of the plate portion, and a groove portion provided on an outer peripheral side of the notch portion. A method for molding a resin stator body, wherein a gate portion is provided substantially at the center in a circumferential direction of a hole-shaped hollow portion formed at the time of molding to provide the cutout portion, and the gate portion is passed through at the time of injection of molding material. The weld was removed from the groove by flowing a part of the molding material.
[0013]
According to a second aspect of the present invention, there is provided a stator forming method according to the first aspect, further comprising: forming a throttle portion having a shape in which the cross-sectional area is once narrowed and enlarged again near the outer peripheral end of the gate portion. The gate portion is broken at the throttle portion when the gate is cut.
[0014]
In the prior art shown in FIGS. 6 to 10, the reason that cracks and the like are easily generated in the plate portion 6 is that both the weld portion 11 and the stress concentration portion are located in the groove portion 7. If at least one of the two can be removed from the groove 7, stress will not be concentrated on a portion having relatively small strength, so that the strength of the plate portion 6 can be improved. However, one stress concentration portion is a problem inherent to the groove portion 7 due to the thinness of the groove portion 7, and therefore, the stress concentration portion cannot be removed from the groove portion 7. Therefore, it is an object of the present invention to remove the remaining weld portion 11 from the groove portion 7.
[0015]
As shown in FIG. 9, the weld portion 11 is formed at the junction of the molding material along the junction, and the junction is formed on the outer peripheral side of the projection set in the cavity of the mold. Also, since the projection has the same cross-sectional shape perpendicular to the axis and the opening shape of the lightening portion 10, the confluence portion is formed on the outer peripheral side of the lightening portion 10. In addition, since the flow of the material divided into two parts by the protrusions goes around to the back side of the protrusions in almost the same way and merges, the merging portion is formed near the circumferential center line of the protrusion on the outer peripheral side of the protrusion, that is, lightening It is formed near the circumferential center line C of the lightening portion 10 on the outer peripheral side of the portion 10.
[0016]
Therefore, in the related art, since the circumferential center line C of the lightening portion 10 is arranged in the groove 7 in the related art, the weld portion 11 formed near the circumferential center line C is formed in the groove 7. In contrast to this, as in the molding method according to claim 1 of the present invention, a gate portion is provided at substantially the center in the circumferential direction of the lightening portion, and when the molding material is injected, the gate portion is radially inserted through the gate portion. When a part of the molding material is caused to flow outward, the lightening portion is divided into two in the circumferential direction by the gate portion, and the circumferential center line of each of the lightened portions is displaced in one circumferential direction from the groove portion. In addition, the weld formed along the center line in the circumferential direction is also divided into two parts, and each of the parts is separated from the groove. That is, since the molding material that has passed through the gate portion spreads to both sides in the circumferential direction on the outer peripheral side of the gate portion and expands beyond the width of the groove portion, the weld portion is separated from the groove portion and the portion other than the relatively thick groove portion is formed. , Two on each side of the groove with the groove in between.
[0017]
Further, when the stator body is formed by the above-described method and is taken out of the mold having the disk gate structure, a stator body in which the gate portion is integrally formed in addition to the top-shaped disk gate portion is taken out. In the removing step, it is necessary to remove the gate part together with the disk gate part. The gate portion is a rod-shaped member extending in the radial direction, and is connected at its inner peripheral end to the outer peripheral edge of the disk gate portion and at its outer peripheral end to the bottom surface of the cutout portion of the stator body. . In order to remove the gate portion, it is necessary to break the gate portion. However, as in the molding method according to claim 2 of the present invention, a narrowed portion having a shape in which the cross-sectional area is once narrowed and enlarged again near the outer peripheral end of the gate portion. Is provided so that the gate portion is broken at the narrowed portion when the gate is cut. When the disk gate portion is removed, the gate portion can be broken off from the narrowed portion by the impact. Further, since the gate portion is broken at the throttle portion by providing the throttle portion of the above shape, the removal mark of the gate portion remaining on the bottom surface of the cutout portion of the stator body always becomes a removal mark of a convex shape, and thus the removal mark is removed. It becomes concave, and it is possible to prevent the occurrence of new stress concentration here.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, a molding method according to the embodiment has the same shape as the stator of FIG. Which is characterized by having the following procedures or steps. However, in the stator formed here, a removal mark 12a of the gate portion 12 is left on the bottom surface 8a of the notch 8 as a protrusion.
[0019]
That is, as shown in FIGS. 3 to 5, the notch 8 is provided when the phenol resin stator body 1 is injection-molded as a molded product with the disk gate 9 using a die having a disk gate structure. Gate portions 12 are provided at substantially the center in the circumferential direction of the hole-shaped lightening portion 10 to be formed, and a cross-sectional area (flow-path cross-sectional area) is once narrowed toward an outer peripheral end of the gate portion 12. An aperture portion 13 having a shape to be enlarged again is provided. The gate portion 12 is a rod-like member having a substantially rectangular cross section extending in the radial direction of the stator main body 1 and having an inner peripheral end connected to the outer peripheral edge of the disk gate 9 and an outer peripheral end connected to the stator main body. The notch 8 is connected to the bottom surface 8a. The provision of the gate portion 12 divides the lightening portion 10 into two parts in the circumferential direction, and the projection set in the cavity of the mold to form the two lightening parts 10 is also divided into two parts in the circumferential direction. Can be erected. The narrowed portion 13 is once narrowed and re-enlarged in the circumferential direction as described above, and has the same thickness as the entire plate portion 6 in the groove 7. Further, in order to make the removal mark 12a as small as possible, it is preferable that the portion where the cross-sectional area of the narrowed portion 13 has been expanded again is located on the bottom surface 8a of the cutout portion 8.
[0020]
When the molding material is injected into the mold, the molding material enters the cavity on the outer peripheral side from the sprue through the disk-shaped disk gate as shown by the arrow in FIG. Each of the projections is partially divided into two portions, which pass through the newly provided gate portion 12, and extend on both sides in the circumferential direction on the outer peripheral side of the gate portion 12 to extend beyond the width of the groove portion 7. Converges on the outer peripheral side of each protrusion with the molding material that has further wrapped around the outside. Therefore, two welds 11 are formed on the other side of the groove 7 on both sides of the groove 7 except for the relatively thick groove 7 apart from the groove 7. Where the weld portion 11 is actually formed can be adjusted by increasing or decreasing the amount (flow rate) of the molding material passing through the gate portion 12, and if the flow rate is large, the weld portion 11 is formed in the groove portion. 7 and the flow rate is small, there is a relation that the weld portion 11 approaches the groove portion 7. If the flow rate is too low, the provision of the gate portion 12 becomes meaningless, so care must be taken. At least the starting point on the inner peripheral side of each weld portion 11 is not the bottom surface 8a of the cut portion 8 but the side surface 8b of the cut portion 8. Ensure the flow rate so that
[0021]
Therefore, according to the molding method including such procedures or steps, the stress concentration portion is still located in the groove portion 7, whereas the weld portion 11 is divided into two portions and the relatively thick groove portion 7 is formed. Since they are formed in other parts, the positions are separated from each other, so that stress is not concentrated on the parts having low mechanical strength. Accordingly, the strength of the plate portion 6 can be improved, and the occurrence of breakage such as a crack in the plate portion 6 can be effectively prevented. The strength improvement of the plate portion 6 is about 30% as compared with the conventional product.
[0022]
In addition, a narrowed portion 13 having a shape that once narrows and re-enlarges the cross-sectional area is provided near the outer peripheral end of the gate portion 12, so that a broken portion of the gate portion 12 is specified, and the gate portion 12 is moved to the narrowed portion 13. Breaks easily. Therefore, when the stator body 1 molded by the above method is removed from the mold and the top-shaped disc gate portion 9 is removed by a conventional method, the gate portion 12 is automatically folded from the narrowed portion 13 by the impact applied at this time. Therefore, the gate portion 12 can be removed together with the disk gate portion 9 without increasing the number of steps and steps.
[0023]
In addition, since the throttle portion 13 having the above-described shape is provided so that the gate portion 12 is broken at the throttle portion 13, the removal mark 12a of the gate portion 12 remaining on the bottom surface 8a of the cutout 8 of the stator body 1 always has a convex shape. It becomes a removal mark. Therefore, it is possible to prevent the removal marks 12a from forming a concave shape and generating a new stress concentration there.
[0024]
Further, the above method has the following advantages.
[0025]
{Circle around (1)} When the required strength is not so large, the weight of the stator can be reduced by converting the increased strength of the plate portion 6 by the above effect into a thinner wall.
[0026]
{Circle around (2)} The gate portion 12 is provided substantially at the center in the circumferential direction of the lightening portion 10 and the strength is improved by removing the weld portion 11 from the groove portion 7. It is not necessary to specify the shape of 8 as a special one. Therefore, the present invention can be applied to a stator having notches 8 of various shapes as necessary.
[0027]
【The invention's effect】
The present invention has the following effects.
[0028]
That is, in the method of forming a stator according to the first aspect of the present invention having the above-described structure, a gate portion is provided substantially at the center in the circumferential direction of the hollow portion, and a part of the molding material passes through the gate portion when the molding material is injected. In order to remove the weld from the groove by flowing the, the stress concentration portion is still located in the groove, whereas the weld is divided into two parts and the parts other than the relatively thick groove The two parts are separated from each other. Therefore, since stress is not concentrated on a portion having low mechanical strength, the strength of the plate portion can be improved, and the occurrence of breakage such as cracks in the plate portion can be effectively prevented.
[0029]
Further, when the required strength is not so large, the stator can be reduced in weight by converting the increased strength of the plate portion by the above effect into a thinner portion.
[0030]
In addition, a gate is provided at the approximate center in the circumferential direction of the lightening portion, and the strength is improved by removing the weld from the groove, so the shape of the notch is special because the strength is improved. There is no need to specify. Therefore, the present invention can be applied to a stator having notches of various shapes as necessary.
[0031]
In addition to the above, in the method of forming a stator according to the second aspect of the present invention having the above-described configuration, a throttle portion having a shape that once narrows the cross-sectional area and expands again is provided near the outer peripheral end of the gate portion. Since the gate portion is broken at the narrowed portion during gate cutting, the gate portion can be removed without extra work.
[0032]
In addition, since the gate portion is broken at the throttle portion by providing the throttle portion having the above shape, the removal mark of the gate portion remaining on the bottom surface of the cutout portion of the stator body always becomes a removal mark of a convex shape. Therefore, it is possible to prevent the removal marks from becoming concave portions and generating new stress concentration here.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of a stator molded by a molding method according to an embodiment of the present invention. FIG. 2 is a front view of a main part of the stator. FIG. 3 is a partial perspective view of a molded product with a gate. 4 is a front view of a main part of a molded product with a gate portion. FIG. 5 is a partially enlarged view of FIG. 4. FIG. 6 is a partial perspective view of a stator molded by a molding method according to a conventional example. FIG. 8 is a partial front view of a molded article with a gate portion. FIG. 9 is a partially enlarged view of FIG. 8. FIG. 10 is an explanatory view showing the flow of molding material.
DESCRIPTION OF SYMBOLS 1 Stator main body 2 Blade 3 Outer ring 4 Outer race 5 Cylindrical part 6 Plate part 6a Outer end face 7 Groove part 8 Notch part 8a Bottom surface 8b Side surface 9 Disk gate part 10 Lightening part 11 Weld part 12 Gate part 12a Removal mark 13 Narrow part

Claims (2)

A resin stator body having an annular plate portion (6), a notch (8) provided on an inner peripheral edge of the plate portion (6), and a groove (7) provided on an outer peripheral side of the notch (8); A method of molding (1),
A gate portion (12) is provided substantially at the center in the circumferential direction of a hole-shaped lightening portion (10) formed at the time of molding to provide the cutout portion (8), and molding is performed through the gate portion (12) at the time of injection of a molding material. A method for forming a stator, characterized in that the weld (11) is removed from the groove (7) by flowing a part of the material. The method for forming a stator according to claim 1,
Near the outer peripheral end of the gate portion (12), there is provided a throttle portion (13) having a shape in which the cross-sectional area is once narrowed and enlarged again, and the gate portion (12) breaks at the throttle portion (13) when the gate is cut. A method for forming a stator, characterized in that:

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