JP5702580B2 - Oil seal mold - Google Patents

Description

  The present invention relates to an oil seal mold suitable for molding an oil seal having a screw projection that exerts a pump action on a seal surface of a seal lip.

  Conventionally, it is mounted on an annular gap between a housing and a shaft as two members that are assembled so as to be relatively rotatable, and is made of a rubber-like elastic body to seal the annular gap and prevent leakage of lubricating oil as a sealing fluid. Oil seals are frequently used. As one type of such an oil seal, there is known one in which a plurality of spiral screws that exhibit a pumping action are formed on the seal surface of a seal lip (for example, see Patent Document 1).

  FIG. 6 shows an example of an oil seal having a conventional screw projection, and the conventional oil seal 50 is mounted between a rotary shaft 51 as a shaft and a housing 52. The oil seal 50 is formed by integrally baking a seal body 55 formed of a rubber-like elastic body on an annular reinforcing ring 54 having a substantially L-shaped cross section.

  The seal body 55 includes an annular seal lip 61 formed so as to gradually decrease in diameter from an inner peripheral portion of the reinforcing ring 54 toward a sealing side OS in which a sealing fluid such as lubricating oil (not shown) is located, and a reinforcement An annular dust strip 62 is formed so as to be gradually reduced in diameter from the inner peripheral portion of the ring 54 toward the atmosphere side AS, and the seal lip 61 has an appropriate fastening allowance with the rotating shaft 51. The lip tip 64 is in contact with the rotating shaft 51. The seal lip 61 has an oil surface 65 having a predetermined oil surface angle that is expanded from the lip tip 64 toward the sealing side OS, and a predetermined diameter that is expanded from the lip tip 64 toward the atmosphere side AS. And a desired region on the lip tip side of the seal surface 66 is in contact with the surface of the rotating shaft 51 with an appropriate tightening margin in the mounted state. In addition, a garter spring 56 is disposed on the radially outer back surface of the lip tip 64 of the seal lip 61 to hold a radial tension between the seal lip 61 and the rotary shaft 51.

  Further, the sealing surface 66 that comes into contact with the rotating shaft 51 in the mounted state has a pumping action in which a sealing fluid such as lubricating oil (not shown) that is about to leak from the sealing side OS toward the atmosphere side AS is always located on the sealing side OS. A plurality of screw protrusions 71 having a protrusion are provided. The screw projection 71 has the shape shown in FIGS. 7 and 8, the angle of inclination angle θ1 is about 20 to 30 degrees, the angle of apex angle θ2 is about 80 to 120 degrees, and the height from the seal surface 66 to the apex. The section h has a substantially triangular mountain shape with a dimension h of about 0.015 to 0.08 mm, and the tip 71a of the screw protrusion 71 located on the lip tip side is connected to the lip tip 64. The lip tip 64 is formed by finishing with a knife cut using an oil seal finishing knife (not shown).

  In general, as shown in FIG. 9, the oil seal 50 is provided with a reinforcing ring 54 in a cavity 81 of an oil seal mold 80, and an unvulcanized rubber cloth (not shown) is vulcanized and molded. A molded product (not shown) is taken out from the sealing die 80, and then a garter spring is cut after cutting an unnecessary portion 85 shown by a hatched area in FIG. 9 located outside the lip tip 64 of the molded product in the axial direction with a knife. It is manufactured by attaching 56.

  Therefore, in order to provide the screw protrusion 71 on the seal surface 66 of the seal lip 61, as shown in FIG. 9, a tapered shape that previously constitutes a part of the cavity 81 of the oil seal mold 80 (only part of which is shown). It is necessary to form a thread groove 83 (exaggerated in FIG. 9) for forming the screw protrusion 71, that is, a recess corresponding to the shape of the screw protrusion 71 on the screw forming surface 86. The screw forming surface 86 includes a seal surface forming region 82 for forming the seal surface 66 and a part of an unnecessary portion 85 connected to the sealing side OS of the seal surface forming region 82.

  Conventionally, cutting by engraving is used to form the thread groove 83 (see, for example, Patent Document 1). Further, as a processing means for the thread groove 83, there is one using a cutter (for example, see Patent Document 2). ).

Japanese Patent Laid-Open No. 08-178082 JP 2003-254439 A

  However, in the conventional oil seal mold 80 described above, the thread groove 83 is formed by cutting by engraving or processing using a cutter, so that the thread groove 83 cannot be easily formed. was there.

  That is, in the conventional oil seal mold 80, a plurality of screw grooves 83 must be formed one by one, which leads to complicated and complicated processing steps and high processing accuracy. Processing took a lot of time.

  Therefore, there is a demand for an oil seal mold that can easily form a thread groove.

  This invention is made | formed in view of this point, and it aims at providing the metal mold | die for oil seals which can form a thread groove easily.

In order to achieve the above-mentioned object, the oil seal mold according to the first aspect of the present invention is characterized in that a threaded oil having a screw protrusion that exerts a pump action on the seal surface of the seal lip. In an oil seal mold for molding a seal, a thread groove for forming the screw projection is formed on a tapered thread forming surface including at least a seal surface forming region for forming the seal surface. It is formed by rolling by pressing a plurality of thread groove forming protrusions provided on the die, and a portion of the thread forming surface including the planned formation position of the lip tip is provided with a height of the thread groove forming protrusion. This is in that a recess having a depth smaller than the height is provided . By adopting such a configuration, the plurality of screw grooves can be securely and securely formed by a simple method of rotating at least one of the plurality of screw groove forming protrusions provided on the rolling die against the screw forming surface. It can be formed easily. Further, the depth of the screw groove transferred to the screw forming surface by the rolling die can be made shallower than the portion where the concave portion is not formed by the depth dimension of the concave portion. That is, by a simple method of forming a recess on the screw forming surface, the depth of one thread groove is shallow at the lip tip side portion where the recess is formed, and on the side opposite to the lip tip where no recess is formed. Can be deep in the part. That is, the depth of one screw groove can be divided into a shallow portion and a deep portion. As a result, the height of one screw projection transferred and formed on the seal surface of the oil seal can be lowered at the lip tip side portion and can be made high at the portion opposite to the lip tip side.

According to the oil seal mold of the present invention described in claim 1, a plurality of screw seal forming protrusions provided on the rolling die are pressed against the screw forming surface and at least one of them is rotated by a simple method. There are excellent effects such as that the screw groove can be reliably and easily formed. Further, the depth of one screw groove is made shallow at the lip tip side portion where the recess is formed by a simple method of forming a recess in a portion including the planned formation position of the lip tip of the screw forming surface. Further, it can be deepened at a portion opposite to the tip of the lip where no recess is formed. That is, it has an excellent effect that the depth of one screw groove can be divided into a shallow portion and a deep portion. As a result, there is an excellent effect that the height of one screw protrusion transferred and formed on the seal surface of the oil seal can be lowered at the lip tip side portion and increased at the portion opposite to the lip tip side.

Sectional drawing which shows the principal part of 1st Embodiment of the metal mold | die for oil seals which concerns on this invention. It is a schematic diagram which shows the formation method of the screw groove in the metal mold | die for oil seals of FIG. 1, (a) is a state immediately before screw groove formation, (b) is a screw groove formation state. The same figure as FIG. 1 which shows the principal part of 2nd Embodiment of the metal mold | die for oil seals concerning this invention. FIG. 4 is a view similar to FIG. 2 showing a method for forming a thread groove in the oil seal mold of FIG. The schematic diagram which exaggerates and shows one screw protrusion transcribe | transfer-formed on the sealing surface of the oil seal shape | molded with the metal mold | die for oil seals of FIG. Half sectional view showing an example of a conventional oil seal 6 is an enlarged view of the screw protrusion of the oil seal of FIG. FIG. 7 is an enlarged sectional view taken along line YY in FIG. Sectional drawing which shows the principal part of the conventional oil seal mold

  The present invention will be described below with reference to embodiments shown in the drawings.

  1 and 2 show a first embodiment of an oil seal mold according to the present invention. FIG. 1 is a cross-sectional view showing a main part, and FIG. 2 is a thread groove in the oil seal mold of FIG. It is a schematic diagram which shows the formation method.

  The oil seal mold 1 of the present embodiment is exemplified for use in molding the oil seal 50 having the above-described conventional plurality of screw protrusions 71 (see FIGS. 6 to 8). In addition, about the same structure as the conventional oil seal 50 mentioned above, the same code | symbol is attached | subjected in drawing and the description is abbreviate | omitted.

  As shown in FIG. 1, an oil seal mold 1 (hereinafter simply referred to as a mold) according to this embodiment includes at least an upper mold 1A shown in the upper part of FIG. 1 and a lower mold 1B shown in the lower part of FIG. A cavity 2 is formed by combining a pair of upper and lower molds 1 that can be freely opened and closed, and a reinforcing ring 54 (see FIGS. 6 to 8) is attached to the cavity 2 and an unvulcanized rubber fabric is put therein. A molded product can be obtained by vulcanization molding.

  The lower mold 1 </ b> B that is one mold 1 is provided with a screw forming surface 3 that constitutes a part of the cavity 2. The screw forming surface 3 is formed in a thin taper shape in the upper part of FIG. 1 which is the sealing side OS of the oil seal 50. The screw forming surface 3 has a screw protrusion 71 (see FIGS. 6 to 8). A plurality of screw grooves 4 are provided for forming the.

  That is, the screw forming surface 3 of the mold 1 in the present embodiment is the sealing surface forming region 82 for forming the sealing surface 66 (see FIGS. 6 to 8) and the sealing side OS of the sealing surface forming region 82. A part of the unnecessary portion 85 (see FIG. 9) of the lip tip 64 (see FIGS. 6 and 7) which is cut by a knife after molding is included.

  The thread groove 4 of the present embodiment is formed by a rolling process using the rolling die 10. The rolling die 10 used here is formed in a cylindrical shape, and a plurality of thread groove forming protrusions 11 are provided on the peripheral surface thereof. Then, in the state immediately before the thread groove formation shown in FIG. 2 (a), the thread groove forming protrusion 11 provided on the peripheral surface of the rolling die 10 is made to face the thread forming surface 3, and thereafter FIG. 2 (a). As shown by a thick arrow, the thread groove forming projection 11 is pressed against the thread forming surface 3 with a predetermined pressure F, and at least one of the mold 1, the lower mold 1B or the rolling die 10 in this embodiment, In this embodiment, the rolling die 10 is formed by rolling. The thread groove formation state of the thread groove 4 formed by this rolling process is shown in FIG.

  Here, the height dimension H of the thread groove forming projection 11 of the rolling die 10 and the depth dimension HA of the thread groove 4 formed on the thread forming surface 3 are substantially the same, and the depth of the thread groove 4 The dimension HA and the height dimension h of the screw projection 71 formed on the oil seal 50 are substantially the same.

  The number of rolling dies 10 used for processing the thread groove 4 may be one. Of course, a plurality of rolling dies 10 can be provided as required according to the design concept and the like. In addition, forming the rolling die 10 with a material harder than the mold 1 is important in forming the thread groove 4 by rolling. In this case, the mold 1 is generally formed of a structural alloy steel material, while a tool steel material harder than the structural alloy steel material is used as the material of the rolling die 10.

  Since other configurations are the same as those of the conventional mold, detailed description thereof is omitted.

  Next, the operation of the present embodiment having the above-described configuration will be described.

  According to the mold 1 of the present embodiment, the screw groove 4 for forming the screw protrusion 71 on the screw forming surface 3 is formed by pressing a plurality of screw groove forming protrusions 11 provided on the rolling die 10. Since it is formed by manufacturing, a plurality of screw grooves 4 are reliably and easily formed by a simple method of rotating at least one of the screw groove forming protrusions 11 provided on the rolling die 10 against the screw forming surface 3. Can be formed.

  Further, according to the mold 1 of the present embodiment, a plurality of screw groove forming projections 11 provided on the rolling die 10 are pressed against the screw forming surface to rotate the rolling die 10 in a simple manner. Since the thread groove 4 can be formed, the plurality of thread grooves 4 can be easily formed in one continuous process, so that it takes less time for processing than in the conventional case.

  FIG. 3 is a cross-sectional view showing the main part of a second embodiment of the oil seal mold according to the present invention.

  The mold 21 of the present embodiment has a thread groove forming projection of the rolling die 10 on the part including the formation position 26 of the lip tip 64 in the thread forming surface 3 of the mold 1 of the first embodiment described above. The concave portion 25 having a depth dimension smaller than the height dimension of 11 is provided along the circumferential direction.

  That is, as shown in FIG. 3, the mold 21 of this embodiment is a pair of upper and lower molds 21 that can be freely opened and closed, and includes at least an upper mold 21A shown in the upper part of FIG. To form a cavity 22, and a reinforcing ring 54 (see FIGS. 6 to 8) is attached to the cavity 22, and an unvulcanized rubber cloth is put into a vulcanized mold to obtain a molded product. Can be done.

  One mold 21, the lower mold 21 </ b> B in the present embodiment, is provided with a screw forming surface 23 that constitutes a part of the cavity 22 as in the mold 1 of the first embodiment described above. The screw forming surface 23 is formed in a thin taper shape in the upper part of FIG. 3, which is the sealing side OS of the oil seal 50. The screw forming surface 23 is provided with a plurality of screw grooves 24 for forming screw protrusions 71 (see FIGS. 6 to 8), and a position where the lip tip 64 is to be formed on the screw forming surface 23. 26 is provided with a concave portion 25 having a depth dimension D smaller than the height dimension H (see FIG. 4) of a thread groove forming projection 31 of a rolling die 30 to be described later.

  That is, the screw forming surface 23 of the mold 21 in the present embodiment is a seal surface forming for forming the seal surface 66 (see FIGS. 6 to 8) as in the mold 1 of the first embodiment described above. It includes a region 82 and a part of an unnecessary portion 85 (see FIG. 9) of a lip tip 64 (see FIGS. 6 and 7) that is cut by a knife after molding that is connected to the sealing side OS of the seal surface forming region 82. Yes.

  As in the first embodiment described above, the thread groove 24 of the present embodiment has a plurality of screws provided on the peripheral surface of the cylindrical rolling die 30 in the state immediately before the thread groove formation shown in FIG. The groove forming protrusion 31 is made to face the screw forming surface 23, and then the screw groove forming protrusion 31 is pressed against the screw forming surface 23 with a predetermined pressure F as shown by a thick arrow in FIG. The die 21 is formed by a rolling process in which the rolling die 30 is rotated in at least one of the lower die 21B and the rolling die 30 in the present embodiment. The thread groove forming state of the thread groove 24 formed by this rolling process is shown in FIG.

  Here, in the present embodiment, the height dimension H of the thread groove forming protrusion 31 is about 0.05 mm, and the depth dimension D of the recess 25 is about 0.025 mm. Of course, the depth dimension D of the recess 25 may be smaller than the height dimension H of the thread groove forming protrusion 31 of the rolling die 30.

  A boundary portion between the screw forming surface 23 formed on the sealing side OS and the concave portion 25 is formed in an unnecessary portion 85 in the molded product (FIG. 3).

  Therefore, the recessed part 25 of the depth dimension smaller than the height dimension of the thread groove formation protrusion 31 is provided in the circumferential direction in the part including the formation position 26 of the lip tip 64 in the screw forming surface 23. It will be.

  The thread groove 24 of the present embodiment is provided on the peripheral surface of the rolling die 30 in the state immediately before the thread groove formation shown in FIG. 4A, similarly to the thread groove 4 of the mold 1 of the first embodiment described above. The plurality of thread groove forming protrusions 31 are made to face the thread forming surface 23 on which the recesses 25 are formed, and then the thread groove forming protrusions 31 are moved as shown by thick arrows in FIG. Rolling process for pressing the screw forming surface 23 with a predetermined pressure F and rotating the die 21, at least one of the lower die 21 </ b> B or the rolling die 30 in this embodiment, or the rolling die 30 in this embodiment. It is formed by. The thread groove 24 formed by the rolling process can be shallow in a portion where the recess 25 is formed and deep in a portion where the recess 25 is not formed. That is, as shown in FIG. 4B, the depth of one screw groove 24 is divided into a shallow portion 24a having a depth dimension of about 0.025 mm and a deep portion 24b having a depth dimension of about 0.05 mm. can do. The shallow portion 24a of the screw groove 24 is provided on the lip tip side of the seal surface 66, and the deep portion 24b of the screw groove 24 is provided on the side opposite to the unnecessary portion 85 and the lip tip side of the seal surface 66.

  That is, the height dimension H of the thread groove forming protrusion 31 of the rolling die 30, the depth dimension HA of the deep portion 24b of the thread groove 24 formed on the thread forming surface 23, and the oil seal 50A shown in FIG. The height dimension hb of the formed high threaded protrusion 71Ab is substantially the same.

  Further, the depth dimension HB of the shallow portion 24 a of the screw groove 24 formed on the screw forming surface 23 is the same as the depth dimension HA of the deep portion 24 b of the screw groove 24 subtracted from the depth dimension D of the recess 25. At the same time, the height dimension ha of the low-profile screw projection 71Aa formed on the oil seal 50A shown in FIG.

  In addition, the height dimension ha of the screw projection 71Aa having a low height formed on the oil seal 50A is changed from the height dimension hb of the screw projection 71Ab having a high height formed on the oil seal 50A to the depth dimension D of the recess 25. It is almost the same as subtracting.

  Therefore, one screw projection 71 transferred and formed on the seal surface 66 of the oil seal 50A molded by the mold 21 of the present embodiment has a low height at the lip tip side portion and is opposite to the lip tip side. High in the part. One screw projection 71 transferred and formed on the seal surface 66 of the oil seal 50A molded by the mold 21 of this embodiment is exaggerated in FIG. In FIG. 5, reference numeral 71 </ b> Aa indicates a lower portion of the protrusion 71 formed on the lip tip side which is the sealing side OS, and reference numeral 71 </ b> Ab is formed on a part opposite to the lip tip side which is the atmospheric side AS. The high part of the screw protrusion 71 is shown. Here, a stepped portion 66a corresponding to a boundary portion between the screw forming surface 23 of the mold 21 and the recessed portion 25 is formed on the seal surface 66 of the oil seal 50A. A low screw projection 71Aa and a high screw projection 71Ab are formed on the opposite side.

  Further, in the mold 21 of the present embodiment, the screw groove 24 is formed after the recess 25 is formed on the screw forming surface 23. However, the recess 25 may be formed after the screw groove 24 is formed. Either the thread groove 24 or the recess 25 may be formed first. However, as in the present embodiment, forming the thread groove 24 after forming the recess 25 is more stable than the case of forming the recess 25 after forming the thread groove 24. Preferred in terms.

  Since other configurations are the same as those of the conventional mold 1 of the first embodiment, detailed description thereof will be omitted.

  According to the mold 21 of the present embodiment, the same effects as those of the mold 1 of the first embodiment described above can be obtained and transferred to the screw forming surface 23 by the thread groove forming protrusion 31 of the rolling die 30. The depth of the threaded groove 24 can be made shallower by the depth dimension of the recessed portion 25 than the portion where the recessed portion 25 is not formed.

  That is, according to the mold 21 of the present embodiment, the depth of one screw groove 24 is shallow in the portion where the recess 25 is formed by a simple method of forming the recess 25 in the screw forming surface 23. It can be deepened in the portion where the recess 25 is not formed. That is, the depth of one screw groove 24 can be divided into a shallow portion 24a and a deep portion 24b (see FIGS. 3 and 4).

  As a result, according to the mold 21 of the present embodiment, one screw projection 71 transferred and formed on the seal surface 66 of the oil seal 50A has a height at the lip tip side portion located on the sealing side OS in the oil seal 50A. The screw projection 71Aa having a low height and the screw projection 71Ab having a high height on the side opposite to the lip tip side located on the atmosphere side AS in the oil seal 50A can be used (see FIG. 5). Furthermore, in the mold 21 according to the present embodiment, the height ha of the screw projection 71Aa having a low height (the screw projection on the lip tip side) can be easily controlled by changing the depth of the recess 25.

  In addition, this invention is not limited to each embodiment mentioned above, A various change is possible as needed.

  For example, as the shape of the screw protrusion of the oil seal formed by the thread groove forming protrusion of the rolling die, various shapes such as a boat bottom shape and a tapered shape can be used as long as there is no undercut. Furthermore, the height of one screw projection 71 can also be made into three types by making the depth of a recessed part into two types.

1, 21 (for oil seal) Die 1A, 21A Upper die 1B, 21B Lower die 2, 22 Cavity 3, 23 Thread forming surface 4, 24 Thread groove 10, 30 Rolling die 11, 31 Groove forming protrusion 24a Shallow Portion 24b Deeper portion 25 Recessed portion 26 (Lip tip) scheduled formation position 50, 50A Oil seal 54 Reinforcement ring 55 Seal body 61 Seal lip 64 Lip tip 66 Seal surface 71 Screw projection 71a Tip portion 71Aa Low portion 71Ab High portion 85 Unnecessary portion D (depth of recess) H (height of thread groove forming projection) height HA (depth of thread groove) depth HB (shallow depth of groove) h (screw projection) Height dimension ha (for low-profile screw projections) Height dimension hb (for high-profile screw projections) Height dimension

Claims (1)

In an oil seal mold for molding an oil seal having a plurality of screw projections that exert a pump action on the seal surface of the seal lip,
At least a plurality of thread groove forming protrusions provided on a rolling die have thread grooves for forming the thread protrusions on a tapered thread forming surface including a seal surface forming region for forming the seal surface. It is formed by rolling process by pressing ,
An oil seal mold characterized in that a recess having a depth smaller than the height of the thread groove forming projection is provided in a portion of the thread forming surface including a position where the lip tip is to be formed. .

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