CN109291115B - Joint processing method and joint cutter for sealing ring - Google Patents

Abstract

According to the joint processing method of the sealing ring and the joint cutting knife, the joint of the sealing ring with the special step-shaped cutting part can be processed with high precision and high efficiency through mechanical processing without deforming the annular sealing ring blank; the work fixing and conveying unit is provided with a work fixing and conveying unit for clamping and conveying a seal ring blank in the same posture, wherein the annular seal ring blank is placed on a processing table in a mode that the axial direction is vertical to the processing table, the work is positioned at the positions opposite to each other in the inner circumferential surface of the seal ring blank (the work) through a pair of semi-disc-shaped positioning components, then the work pressing component positioned above is lowered to clamp the seal ring blank on the processing table, then the work fixing and conveying unit is moved to the positions of a plurality of cutting units, and a step-shaped seam is formed on the seal ring blank through a seam cutting process performed by each cutting unit.

Description

Joint processing method and joint cutter for sealing ring

Technical Field

The present invention relates to a seam processing method for forming a stepped cut seam of a synthetic resin seal ring which is annular and cut at one position in a circumferential direction, and a seam cutter for performing the method.

Background

The seal ring is in the shape of a discontinuous circular ring having a seam at one position in the circumferential direction, and is mounted in an annular groove provided on the circumferential surface of one of two members (a shaft and a housing) that rotate relative to each other. The seal ring is in slidable close contact with a side wall surface of the annular groove and a circumferential surface of the other member, respectively, to seal an annular gap formed between the two members. Seal rings are used in devices that utilize fluid pressure of hydraulic oil or the like, such as Automatic Transmissions (ATs) and Continuously Variable Transmissions (CVTs) for automobiles, for example.

The seams of the sealing ring are as follows: in recent years, in order to further reduce the amount of leakage of hydraulic oil from a joint cut portion, a large number of stepped joints have been used, such as a slit type (bias cut) in which a plane perpendicular to the circumferential direction is cut, a diagonal type (bias cut) in which a plane perpendicular to the circumferential direction is cut, and a stepped type (step type) in which a plurality of rectangular planes smaller than the slit type joints are formed at different positions in the circumferential direction so as to be perpendicular to the circumferential direction and are cut at one position in the circumferential direction of an annular seal ring.

Synthetic resin is used as a material for the seal ring, and Polytetrafluoroethylene (PTFE) has been mainly used in recent years as a material having excellent sliding characteristics and wear resistance. In addition, the raw materials of the shaft and the shell adopt metal materials.

A general method for producing a seal ring mainly composed of Polytetrafluoroethylene (PTFE) is as follows: the outer and inner peripheral surfaces of the press-molded cylindrical blank are subjected to final machining, and then cut into pieces having the finished width of the seal ring in the radial direction to produce an annular seal ring blank.

In the joint processing method disclosed in patent document 1, the inner and outer peripheral surfaces of the joint forming portion of the ring main body are clamped by the opposing planes of the pair of jigs to make the joint forming portion linear, and after the linear cutting edge having the stepped portion is pressed into the linear joint forming portion to form the joint, the jigs are removed, and at this time, the joint forming portion of the ring main body changes the linear portion into the circular arc portion of the original shape by the tension of the ring main body itself.

In the case of patent document 1, it is considered that the deformation in the elastic deformation of the seal ring material is assumed so that the joint forming portion of the seal ring is formed into a linear shape and then is formed into an arc shape of the original shape by self-tension.

In the case of a highly rigid material such as Polytetrafluoroethylene (PTFE) and the radius of curvature of the outer peripheral surface of the seal ring is as small as 30mm or less, when the seal ring is deformed into a straight shape and then the joint is processed, it is very difficult to restore the seal ring to a shape having the radius of curvature before processing, and in particular, the roundness of the outer peripheral surface of the seal ring is broken, which results in a loss of the sealing function.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent laid-open No. 2003-1584

Patent document 2: japanese patent laid-open No. 2005-212004

Disclosure of Invention

The seam cutting device disclosed in patent document 2 includes: a workpiece restricting unit that restricts the seal ring by a restricting surface having a curvature radius that coincides with the inner circumferential surface and the outer circumferential surface of the seal ring; a radial cutter blade which is shaped like a flat plate and cuts along a radial direction, and a blade tip of which is shaped like an arc having a radius of curvature corresponding to a radius of curvature at an arbitrary radius position within the thickness of the seal ring; a cylindrical surface cutter which is in a cylindrical surface shape bent with the same curvature radius as the cutter point of the radial cutter and cuts along the axial direction; a first slitting knife which is in a shape of a flat plate substantially parallel to the axis and cuts along the axial direction, and a knife tip of which extends in a direction perpendicular to the axis; and a second slitting blade having a flat shape substantially parallel to the axis, wherein the blade edge extends in a direction perpendicular to the axis, and cuts the cylindrical surface cutting blade at the other end in the circumferential direction and on the inner peripheral side in the axial direction at a position cut by the cylindrical surface cutting blade, and the cylindrical surface cutting blade and the first slitting blade are joined to each other.

The seam cutting device has one cutting operation unit, the cutting blades are detachable from each other, and each cutting blade in the following four cutting processes advances or retreats relative to the sealing ring located below, and the radial cutting blade is caused to cut in the radial direction in a state where the sealing ring is restricted by the workpiece restricting unit (first process). Next, a cutter blade formed by joining the cylindrical surface cutter blade and the first slitting blade is axially cut into the cylindrical surface from the first side surface (second step). Then, a cutter constituted by combining the cylindrical surface cutter and the first slitting cutter is axially cut into the cylindrical surface from the second side surface (third step), and a second slitting cutter is axially cut into the cylindrical surface from the side surface (fourth step).

In the second step and the third step, in order to cause the dicing blade to cut into the first side surface and the second side surface, the orientation of the seal ring needs to be changed by changing the direction of the work regulating means, and the cutting position of the dicing blade may not be the same on the first side surface and the second side surface. Therefore, in order to accurately position the seal ring, it is necessary to accurately control the position or posture of the workpiece regulating means, and there is a possibility that the machining becomes complicated.

The main problems of the seam cutting processing device disclosed above are: since the work restricting means is restricted by the restricting surface having the curvature radius matching the inner peripheral surface and the outer peripheral surface of the seal ring, it is necessary to prepare the work restricting means having various curvature radii in accordance with the sizes of the inner peripheral surface and the outer peripheral surface of the seal ring, and the four cutting processes are performed by using the same cutting operation means, so that the time for processing the joint of each seal ring becomes long.

The present invention has been made in view of the above problems, and an object of the present invention is to enable machining of a seal ring seam having a cut portion in a special stepped shape with high precision and high productivity without deforming a seam forming portion of the seal ring.

As a technical means for achieving the above object, a method for processing a joint of a seal ring according to the present invention includes:

a first step: clamping the seal ring blank at a predetermined position by a workpiece fixing and conveying unit, wherein the workpiece fixing and conveying unit comprises: a processing table for cutting the joint, on which a ring-shaped seal ring blank made of synthetic resin is placed so as to be axially perpendicular to the processing table; a pair of half disc-shaped positioning members which are respectively contacted with mutually opposite positions in the inner circumferential surface of the sealing ring blank, and the curvature radius of the positioning members is less than or equal to that of the inner circumferential surface of the sealing ring blank; a first servo cylinder for moving a half disc-shaped positioning member located at a position facing the seam forming part, out of the half disc-shaped positioning members; a fixing member that presses at least two portions of the other side surface of the seal ring material, that is, the top surface of the seal ring material, and a portion that is radially opposed to the seam-forming portion in the circumferential direction, against the bottom surface of the seal ring material, that is, the side surface of the seal ring material that is in contact with the surface of the machining table; and a cylinder for mounting the fixing member and moving the fixing member forward or backward with respect to the surface of the processing table;

a second step: after the seal ring blank is held at a predetermined position by the work fixing and conveying means in the first step and is moved to an axial cutting unit position having a second servo cylinder to which an axial cutter holder is attached, the axial cutter holder is moved forward or backward from above in the vertical direction of the machining table by the second servo cylinder, thereby forming a substantially L-shaped cut surface comprising an arc-shaped cut surface and a linear cut surface on the top surface of the seam forming portion of the seal ring blank, wherein the arc-shaped cut surface is an arc concentric with the inner peripheral surface of the seal ring blank and extending in the circumferential direction, the center angle formed by the both ends of the arc and the axial center of the seal ring blank is 2 alpha, and the center angle between the position where the inner peripheral surface of the seam forming portion of the seal ring blank contacts the semicircular portion of the semi-disc-shaped positioning member and the end of the arc is alpha, the linear cutting surface extends from one end of the circular arc cutting surface in the circumferential direction to the inner circumferential side toward the axial center of the seal ring blank;

a third step: after moving to a radial cutting unit position provided with a third servo cylinder provided with a radial cutter holder after a second step while maintaining a state in which a seal ring blank is clamped at a predetermined position by a workpiece fixing and conveying unit in a first step, the radial cutter holder is advanced or retreated in a direction from an outer side of an outer peripheral surface of the seal ring blank toward the outer peripheral surface by the third servo cylinder, thereby forming a cut surface having an "L" shape in a projected shape on the outer peripheral surface on a seam forming portion of the seal ring blank, wherein the "L" shaped cut surface includes: a cutting plane having a projection straight line parallel to the top surface or the bottom surface of the seal ring material projected on the outer peripheral surface of the seam forming portion of the seal ring material, wherein a central angle formed by both ends of the projection straight line in a plane including the projection straight line and perpendicular to the axial direction is α, one end of the projection straight line is located at a position where the inner peripheral surface of the seam forming portion of the seal ring material contacts the semicircular portion of the positioning member having a semi-circular disk shape, and the other end of the projection straight line passes through one end of an arc formed on the top surface of the seal ring material in the second step and concentric with the inner peripheral surface of the seal ring material, and extends in the radial direction; and a linear cut surface extending from the position of the other end of the projected straight line toward the bottom surface side;

a fourth step: after moving to an outer peripheral side upper cutting unit position including a fourth servo cylinder to which an outer peripheral side upper linear knife holder is attached and an index table that controls a cutting direction of the outer peripheral side upper linear knife through a second step and a third step while maintaining a state in which the seal ring blank is clamped at a predetermined position by the work fixing and conveying unit in the first step, the outer peripheral side upper cutting knife holder is advanced or retracted in a direction from an outer side of an outer peripheral surface of the seal ring blank toward the outer peripheral surface by the fourth servo cylinder, thereby forming a linear cut surface extending from one end of a projection straight line that is formed on the outer peripheral surface of the seal ring blank in the third step and is parallel to a top surface or a bottom surface of the seal ring blank toward the top surface side; and

a fifth step: after forming a joint in the annular seal ring material through the second to fourth steps, the work fixing and conveying unit, which is continuously maintained in a state of holding the seal ring material at the predetermined position, is moved, the fixing member pressing the seal ring material is retreated upward by the air cylinder, and the positioning member located at the position opposite to the joint forming portion is retreated toward the joint forming portion side by the first servo air cylinder, so that the seal ring formed by forming the joint in the seal ring material is taken out.

In addition, another aspect of the present invention is the above invention, wherein the rotary index table is preferably provided with five or more work fixing and conveying units, and the seal ring blank is conveyed to the three cutting units in sequence.

In addition, the joint cutter of the sealing ring is made of metal, and the joint is formed on the annular sealing ring blank made of synthetic resin by sequentially using an axial cutter, a radial cutter and an upper linear cutter on the outer peripheral side; wherein the content of the first and second substances,

the axial cutting knife comprises an axial through curve knife, an axial cut-in curve knife and an inner peripheral side straight line knife, and is cut in along the direction parallel to the axial direction of the sealing ring blank, so that a middle through cutting surface in the thickness direction is formed by the axial through curve knife, a middle cut-in cutting surface in the thickness direction is formed by the axial cut-in curve knife, and an inner peripheral side cutting surface is formed by the inner peripheral side straight line knife, wherein the axial through curve knife is in an arc shape concentric with the inner peripheral surface of the sealing ring blank, the middle part of the thickness of the sealing ring blank penetrates through the width of the sealing ring blank along the direction parallel to the axial direction of the sealing ring blank, and the thickness direction of the sealing ring blank is along the radial direction of the sealing; the axial cutting curve knife is in a circular arc shape concentric with the inner circumferential surface of the sealing ring blank, extends along the circumferential direction from one end of the axial cutting curve knife and forms a notch reaching the middle of the width of the sealing ring blank along the axial direction; the inner circumference side straight line knife is connected with the other end of the axial through curved line knife, the length of the sealing ring blank in the radial direction is from the inner circumference surface of the sealing ring blank to the axial through curved line knife, and the sealing ring blank penetrates through the axial direction;

the radial cutting knife comprises a radial cutting-in transverse curve knife and an outer periphery side lower linear knife, and cuts in from the outer side of the outer periphery of the sealing ring blank towards the axial center direction of the sealing ring blank, so that a width direction middle cutting-in cutting surface is formed by the radial cutting-in transverse curve knife, and an outer periphery side lower cutting-in cutting surface is formed by the outer periphery side lower linear knife, wherein the radial cutting-in transverse curve knife cuts in the width middle of the sealing ring blank from the outer periphery of the sealing ring blank to a thickness direction middle cutting-in cutting surface, the knife tip of the radial cutting-in transverse curve knife is in an arc shape extending along the circumferential direction of the thickness direction middle cutting-in cutting surface, and the length of the knife tip is equal to the; the lower linear cutter on the outer peripheral side is connected with one end of the radial cutting-in transverse curve cutter, and cuts into the middle of the thickness direction to penetrate through the cutting surface and the middle of the thickness direction to cut into the connecting part of the cutting surface;

the outer peripheral side upper portion linear knife cuts from the outer side of the outer peripheral surface of the seal ring material toward the axial center direction of the seal ring material, and the end portion of the intermediate cut-in surface in the width direction cuts from the outer peripheral surface of the seal ring material to the end portion of the intermediate cut-in surface in the thickness direction, and cuts from the intermediate cut-in surface in the width direction to one end surface in the axial direction of the seal ring material, thereby forming an outer peripheral side upper portion cut-in surface.

(effect of the invention)

According to the present invention, a seam processing method and a seam cutter which are highly accurate and have high production efficiency can be provided, in which the following processing method is adopted: the method comprises positioning an annular seal ring blank on a processing table without deforming a seam forming part of a seal ring, pressing at least a part of the top surface of the seal ring blank other than the seam forming part to clamp a workpiece, conveying the workpiece in this state by a plurality of workpiece fixing and conveying units, sequentially moving the workpiece fixing and conveying units to an axial cutting unit provided with an axial cutting knife holder, a radial cutting knife unit provided with a radial cutting knife holder, and an outer periphery upper cutting knife unit provided with an outer periphery upper linear knife holder to perform seam cutting, and finally releasing the workpiece from the workpiece fixing and conveying units.

Drawings

Fig. 1 is a perspective view showing a structure of a stepped seam formed by a seam processing method for a seal ring according to an embodiment of the present invention, as seen from a top surface side of the seal ring.

Fig. 2 is a view showing a state after the joint of the seal ring is expanded from the state shown in fig. 1.

Fig. 3 is a plan view of the seal ring of fig. 1, and shows a top surface side of the seal ring.

Fig. 4 is a view showing the slit shown in fig. 3, wherein (a) is a view from the outer peripheral side of fig. 3 in the direction of 1-1, and (B) is a view from the inner peripheral side of fig. 3 in the direction of 2-2.

Fig. 5 is a plan view of the seal ring of fig. 1, and shows a bottom surface side of the seal ring.

Fig. 6 is a top view of the seal ring on the top surface side in a state where the seal ring is cut and the seal ring is expanded from the state shown in fig. 3.

Fig. 7 is a plan view of the bottom surface side of the seal ring in a state where the seam formed by cutting is widened from the state shown in fig. 5.

Fig. 8 shows the dimensions and seam cut location in a top view of the seal ring shown in fig. 3.

Fig. 9 shows three seam cutters for forming the stepped seam structure of fig. 1 and a slit in a state after cutting to form a seam.

Fig. 10 is a plan view illustrating a workpiece fixing and conveying unit for processing a joint, in which a seal ring blank is placed on a processing table of the workpiece fixing and conveying unit, and a pair of positioning members are arranged.

Fig. 11 is a diagram for explaining operations performed subsequent to the state shown in fig. 10, and shows a state in which the seal ring blank is positioned on the machining table by a pair of positioning members disposed on the inner peripheral side of the seal ring blank.

Fig. 12 is a diagram for explaining operations performed subsequent to the state shown in fig. 11, and shows a state after the seal ring material is fixed by the fixing member which advances and retracts with respect to the processing table.

Fig. 13 is a sectional view taken along line 3-3 of fig. 12.

Fig. 14 is a perspective view of a seal ring material for explaining a second step of the method for joining a seal ring according to the embodiment of the present invention, showing a joint cutter used for cutting in the step, and showing a cut of a cut portion formed by the cutting in a broken line.

Fig. 15 shows a cutting portion and a cutter blade cut in the second step. In the drawings, (a) shows a cut portion (non-hatched portion) in a cross section taken along the line 4-4 shown in fig. 14 and perpendicular to the circumferential direction, and (B) shows a cut portion (non-hatched portion) also taken along the line 5-5 and viewed from the outer peripheral surface side in the circumferential direction.

Fig. 16 is a perspective view of a seal ring material for explaining a third step of the method of processing a joint of a seal ring according to an embodiment of the present invention, showing a joint cutter used for the cutting process in the third step, showing a cut of a cut portion processed in the second step in a broken line, and showing a cut of the cut portion processed in the second step.

Fig. 17 is a front view of the seal ring material shown in fig. 16, and shows a slit of a cut portion cut in the third step.

Fig. 18 shows a cutting portion and a cutter blade cut in the third step. In this figure, (a) shows a cut portion (non-hatched portion) cut along the 6-6 line shown in fig. 17 and viewed in the circumferential direction from the upper surface side, and (B) also shows a cut portion (non-hatched portion) cut along the 7-7 line and viewed in a cross section perpendicular to the circumferential direction.

Fig. 19 is a perspective view of a seal ring material for explaining a fourth step of the method of processing a joint of a seal ring according to the embodiment of the present invention, showing a joint cutter used for the cutting process in the step, showing a cut of a processed cut portion in a virtual line, and showing a cut of the cut portion cut in each of the second step and the third step.

Fig. 20 shows the cut portion and the dicing blade cut in the fourth step, and shows the cut portion (portion without oblique lines) in a cross section taken along the line 8-8 shown in fig. 19 and perpendicular to the circumferential direction.

Fig. 21 is a diagram illustrating a schematic configuration of a seam processing apparatus used in the seam processing method according to the present invention, and is a diagram relating to a modification of the seam processing method.

(symbol description)

1 sealing ring

1a seam cut

1s sealing ring blank

11a, 11b, 11c, 11d are cut

12a, 12b, 12c cutting

13a, 13b cutting

2 left side of the seam

2a outer peripheral upper cut portion

2b inner peripheral side projection

2c outer peripheral lower step portion

21 middle cut-in cutting surface in thickness direction

22 peripheral upper cut surface

23 cut into the middle of the width direction

24 middle through cut surface in thickness direction

25 lower cut surface on the outer periphery

26 inner peripheral side cutting surface

3 right side of the seam

3a outer peripheral side projection

3b inner peripheral side cut part

3c lower cut portion on the outer periphery side

31 middle cut-in cutting surface in thickness direction

32 outer peripheral upper cut surface

33 middle cut surface in width direction

34 middle through cut surface in thickness direction

35 lower cut surface on the outer periphery side

36 inner peripheral side cutting surface

40 axial cutting knife

41 axial through curve cutter

41a knife tip

42 axial incising curve knife

42a knife tip

43 inner peripheral side linear knife

43a knife tip

50 radial cutter

51 radial cutting-in transverse curve cutter

51a knife tip

51b, 51d edge

51c edge knife

52 outer periphery lower linear knife

52a knife tip

60 periphery side upper straight line cutter

60a knife point

70 workpiece fixing and conveying unit

70a processing table

71 positioning component (Movable side)

72 positioning parts (fixed side)

Tool withdrawal groove of 72a cutting knife

73 ring top surface pressing component (fixed component)

74 cutter supporting board (part of processing table)

75 first servo cylinder

100 outer peripheral surface of sealing ring

Outer peripheral surface of 100s seal ring blank

110 top surface of sealing ring

110s Top surface (the other side surface) of blank of sealing ring

Bottom surface of 120 sealing ring

Bottom (side) of 120s seal ring blank

130 inner peripheral surface of sealing ring

Inner peripheral surface of 130s seal ring blank

200 seam processing device

200a rotary indexing table

201 workpiece receiving position

202 axial cutting unit position

203 radial cutting unit position

204 outer circumference side upper cutting unit position

205 workpiece discharge position

211 axial cutting knife holder

212 radial cutter holder

213 outer circumference upper cutter holder

Detailed Description

Hereinafter, a method of processing a joint of a seal ring and a joint cutter of a seal ring according to a preferred embodiment of the present invention will be specifically described.

Fig. 1 is a perspective view showing a structure of a stepped seam cut part 1a processed by a seam processing method for a seal ring according to an embodiment of the present invention, as seen from a top surface 110 side of the seal ring. Fig. 2 is a view showing a state after the seam part of fig. 1 is expanded, and when a cut surface of the seam left side part 2 is formed, a corresponding cut surface of the seam right side part 3 in fig. 2 is also formed. In the seal ring 1, a distance t between the outer peripheral surface 100 and the inner peripheral surface 130 is referred to as a seal ring thickness, and a distance w between the top surface 110 and the bottom surface 120 facing the top surface is referred to as a seal ring width.

When the respective cut surfaces are formed, the thickness direction middle cut-in cut surfaces 21, 31, the outer peripheral side upper cut-in cut surfaces 22, 32, the width direction middle cut-in cut surfaces 23, 33, the thickness direction middle cut-through cut surfaces 24, 34, the outer peripheral side lower cut-in cut surfaces 25, 35, and the inner peripheral side cut surfaces 26, 36 are formed on the seam left side portion 2 and the seam right side portion 3, respectively. In fig. 1, the cut surface of the seam right side portion 3 is shown in parentheses. As shown in fig. 2, the sealing ring 1 is separated at the joint by these cut surfaces.

Fig. 3 is a plan view of the seal ring 1 cut at the seam-cut portion 1a, and shows the top surface 110 side of the seal ring. As shown in fig. 3, the slits 11a, 11b, 11c, 13a can be seen on the top surface 110 side of the seal ring. In addition, the slits 12c are shown by broken lines. The 1-1 direction view and the 2-2 direction view in fig. 3 are shown as (a) and (B) in fig. 4. The slits 12a, 12B, and 13B are visible on the outer peripheral surface of the seal ring 1 shown in fig. 4 (a), and the slit 11d is visible on the inner peripheral surface shown in fig. 4 (B). In addition, the slit 11d is connected to the slit 11 a.

Fig. 5 is a plan view of the bottom surface 120 side of the seal ring cut at the seam cut part 1 a. As shown in fig. 5, the slits 11a, 11b, 12c are visible on the bottom surface 120 side of the seal ring. In addition, the slit 12c is connected to the slit 12 a. In addition, the slit 11c and the slit 13a connected to the slit 11b are indicated by dotted lines.

As described above, the slits 11a, 11b, 11c, 11d, 12a, 12b, 12c, 13a, 13b are connected to the cut surfaces 26, 36, 24, 34, 21, 31, 25, 35, 23, 33, 22, 32 shown in fig. 2, and the seal ring 1 is separated at the seam cut part 1a formed by these cut surfaces 21, 31, 22, 32, 23, 33, 24, 34, 25, 35, 26, 36. Fig. 6 is a plan view of the top surface 110 side of the seal ring in a state where the joint of the seal ring is expanded from the state shown in fig. 3. Fig. 7 is a plan view of the bottom surface 120 side of the seal ring in a state where the joint of the seal ring is expanded from the state shown in fig. 5.

As shown in fig. 6, the seam left side portion 2 is formed in a stepped shape by forming a widthwise middle cut surface 23 in a widthwise middle portion. After the inner peripheral side projecting portion 2b and the outer peripheral side projecting portion 3a are separated, an inner peripheral side cutout portion 3b is formed at the position thereof. After the outer circumferential protrusions 3a are separated, the outer circumferential upper cut-out portions 2a surrounded by the thickness direction intermediate cut-in surface 21, the outer circumferential upper cut-in surface 22, and the width direction intermediate cut-in surface 23 are formed. As shown in fig. 7, a stepped portion is formed by the outer peripheral side lower cut portion 3c where the width direction intermediate cut surface 33 and the outer peripheral side lower cut surface 35 are close to each other.

Fig. 8 shows the main dimensions and the joint cutting position in the plan view of the seal ring 1 shown in fig. 3, and the curvature radius of the outer diameter of the seal ring 1 is R1, the curvature radius of the inner diameter is R2, the curvature radius of the slits 11b and 11c of the joint cut portion extending in the circumferential direction of the seal ring is R, and the axial center of the seal ring 1 is O.

The seam cutting position in the circumferential direction is an arbitrary position on the annular seal ring material 1s before the processing of the seam cutting portion 1a provided in the seal ring 1, but in terms of the relationship with the positioning member 72 in the form of a half disc of the work fixing and conveying unit 70 described later, the contact position of the positioning member 72 and the inner peripheral surface 130s of the seal ring material (referred to as "processing reference point P") is located at the center position of the circumferential length of the seam cutting portion, the slit 12a and the slit 12c are located at the same position, and the positions of the slit 11a and the slit 13a facing the axial center O direction are formed at positions separated from the processing reference point P by an angle α with respect to the axial center O in the plan view of the seal ring 1, that is, the central angle of the circumferential length of the seam cutting portion is 2 α. The straight line M passes through the axial center O of the seal ring 1 and the machining reference point P, and extends in the diameter direction of the seal ring 1.

Fig. 9 shows slits 11a, 11b, 11c, 12a, 12b, 13a, 13b which are visible from the surface of the seal ring 1 in the step-shaped joint shown in fig. 1 formed by the joint processing method for a seal ring according to an embodiment of the present invention. Of these slits, the slit 11a is formed by the axial direction cutting blade 40 in a direction toward the axial center and penetrates the axial direction width w, the slits 11b and 11c are formed by the axial direction cutting blade 40 in an intermediate portion of the radial thickness t, and the slit 11b penetrates the axial direction width w and the slit 11c is formed up to the intermediate portion of the axial direction width w (position of the slit 12b described later). The slits 12a are formed by the radial cutting blade 50 in a direction toward the axial center, the slits 12b are formed by the radial cutting blade 50 at an intermediate portion of the axial width w, and the slits 12a and 12b are formed up to the position of the slit 11c (11b) at the intermediate portion of the thickness t. Further, the slits 13a and 13b are formed at circumferential distal ends of the slits 11c and 12b, respectively, by the outer peripheral side upper linear blade 60 in a radial direction which is a direction toward the axial center. These slits 11a, 11b, 11c, 12a, 12b, 13a, 13b are connected to form cut surfaces of the joint.

When the seam-cut portion 1a is machined in the seal ring material 1s as described above, a workpiece fixing and conveying unit 70 in a seam machining apparatus (not shown) as shown in fig. 10 to 13 is used.

The workpiece fixing and conveying unit 70 includes: a processing table 70a for seam cutting, on which a synthetic resin seal ring material 1s having an annular shape is placed so as to be axially perpendicular to the processing table 70 a; a pair of half disc-shaped positioning members 71, 72 that are in contact with positions that are radially opposed to the inner peripheral surface 130s of the seal ring material 1s, and that have a radius of curvature R that is equal to or less than the radius of curvature R2 of the inner peripheral surface 130s of the seal ring material 1s (R2 ≧ R); a first servo cylinder (not shown) which is located below the machining table and which moves the positioning member 71 to position the seal ring material 1 s; a ring top surface pressing member 73 as a fixing member that presses the other side surface (110s) of the seal ring material 1s against the side surface (120s) that is in surface contact with the machining table 70 a; and an air cylinder (not shown) for mounting the ring top surface pressing member 73 and advancing or retreating the ring top surface pressing member 73 relative to the machining table 70 a.

Fig. 10 shows a pair of half disc-shaped positioning members 71 and 72 arranged on a straight line M passing through the axial center O of the seal ring material 1s and the machining reference point P. The positioning member (fixed side) 72 is configured to be fixed relative to the machining reference point P, and the positioning member (movable side) 71 is configured to face the positioning member 72 on the straight line M and to move relative thereto. A portion of the machining table 70a located at the seam cutting portion of the seal ring (a part of the machining table) is a cutter blade support plate 74 made of synthetic resin, the top surface of the cutter blade support plate 74 is located in the same plane as the surface of the machining table 70a, and the cutter blade support plate 74 is replaceable.

Fig. 11 shows that the seal ring material 1s is positioned on the machining table 70a by moving the positioning member 71 (movable side) along the straight line M by the first servo cylinder (not shown) until it comes into contact with a portion of the inner peripheral surface of the seal ring that faces the machining reference point P. The cutter relief groove 72a is a relief groove of the axial cutter 40, and can be applied to seam cutting of a plurality of seal ring materials 1 s.

Fig. 12 shows a state in which the top surface 110s of the seal ring material is pressed by the ring top surface pressing member 73 as a fixed member, wherein the ring top surface pressing member 73 moves forward or backward with respect to the surface of the machining table 70a by the action of the air cylinder. Fig. 13 is a cross-sectional view taken along line 3-3 in fig. 12, and shows a state in which the ring top surface pressing member 73 presses the top surface 110s of the ring-shaped seal ring material to clamp and fix the annular seal ring material 1s together with the machining table 70 a. As shown in fig. 13, since the height of the positioning members 71, 72 is smaller than the width w of the seal ring material 1s, the top surface 110s of the seal ring material protrudes from the top surfaces of the positioning members 71, 72.

The ring top surface pressing member 73 presses, by air pressure, two portions of the top surface 110s of the seal ring material, which sandwich the seam forming portion, and a portion facing the seam forming portion in the radial direction.

As described above, the method of fig. 10 to 13 is the first step of fixing the seal ring material 1s as a workpiece based on the machining reference point P. This first step is performed at a workpiece receiving position (refer to a workpiece receiving position 201 in fig. 21 described later) of a seam processing apparatus (not shown).

A second process of forming a seam with the axial cutting blade 40 will be described with reference to fig. 14. At this time, the workpiece fixing and conveying unit 70 is moved to an axial cutting unit position (not shown).

The axial direction cutting blade 40 is configured to be cut into and retracted from the top surface (110s) side of the seal ring material in the axial direction by integrally holding a curved blade formed integrally by an axial direction penetration curved blade 41 and an axial direction cutting curved blade 42 and an inner peripheral side linear blade 43 in one axial direction cutting blade holder (not shown) and by attaching the same to a high-precision second servo cylinder (not shown).

The 4-4 direction view and the 5-5 direction view in fig. 14 are shown as (a) and (B) in fig. 15.

The cutting edge 41a (double cutting edge) of the axially penetrating curved blade 41 has a radius of curvature that coincides with the radius of curvature of the cutting position of the intermediate portion in the thickness direction (radial direction) of the seal ring material 1 s. That is, the cutting edge 41a is formed in an arc shape (curvature radius R shown in fig. 8) corresponding to the slit 11 b. The axial length of the axial penetration curved blade 41 including the cutting edge 41a can penetrate the width w of the seal ring material 1 s. Therefore, when the axial penetration curve blade 41 is axially penetrated through the seal ring material 1s, the thickness direction intermediate penetration cut surface 24 is formed as shown in fig. 15 (B). The thickness direction intermediate through cut surface 24 is formed at an arbitrary position between the inner peripheral surface 130s and the outer peripheral surface 100s in the thickness t direction of the seal ring material 1 s. The curved blades 41, 42 and the inner peripheral linear blade 43 at the other end in the circumferential direction thereof are integrally held in a substantially L-shape by an axial cutting blade holder (not shown).

The radius of curvature of the arc shape of the cutting edge 42a (double-edged) of the axial direction cutting curved blade 42 formed continuously with one end in the circumferential direction of the axial direction penetrating curved blade 41 coincides with the radius of curvature at the cutting position of the intermediate portion in the thickness t direction of the seal ring material 1 s. That is, the projection line axially penetrating the cutting edge 41a of the curved blade 41 and the projection line of the cutting edge 42a form the same arc (curvature radius R), and the cutting edge 42a is formed in an arc shape corresponding to the slit 11c extending from the slit 11 b. The circumferential arc length of the slit 11b is the circumferential arc length axially penetrating the cutting edge 41a of the curved blade 41, the circumferential arc length of the slit 11c is the circumferential arc length axially penetrating the cutting edge 42a of the curved blade 42, the circumferential arc lengths of the cutting edge 41a and the cutting edge 42a are equal, and the connection portion between the cutting edge 41a and the cutting edge 42a is located on a straight line M passing through the machining reference point P and the axial center O of the seal ring material 1s shown in fig. 10.

The cutting edge 42a of the axial cutting curved blade 42 is positioned higher than the cutting edge 41a of the axial penetration curved blade 41 in the axial direction, and when the cutting edge 41a penetrates the seal ring material 1s in the axial direction, the cutting edge 42a stops at an intermediate position of the width w of the seal ring material 1 s. As shown in (B) in fig. 15, at the stop position, a thickness direction middle cut surface 21 is formed.

The ridge line of the tip 43a of the inner peripheral side linear blade 43 integrally held by an axial cutting blade holder (not shown) at the other end in the circumferential direction of the axially penetrating curved blade 41 is positioned in the same plane including the ridge line of the tip 41a of the axially penetrating curved blade 41, and the cutting edge 43a is formed linearly. The cutting edge 43a of the inner peripheral side linear blade 43 extends from the other end in the circumferential direction of the axial direction penetrating the curved blade 41 toward the axial center O of the seal ring material 1s in a state where the direction of the straight line is the radial direction of the seal ring material 1 s. Therefore, when the cutting edge 41a of the axial curved knife 41 penetrates the seal ring material 1s in the axial direction, the cutting edge 43a of the inner peripheral side linear knife 43 also penetrates the seal ring material 1s in the axial direction. Therefore, as shown in fig. 15 (a), the inner peripheral cutting surface 26 is formed by the inner peripheral linear blade 43, and the slit 11a and the slit 11d shown in fig. 4 (B) are formed.

Next, a third step of forming a joint by the radial cutter 50 will be described with reference to fig. 16. At this time, the workpiece fixing and conveying unit 70 is moved to a radial cutting unit position (not shown).

The radial cutter 50 is mounted on a high-precision third servo cylinder (not shown) by integrally holding a radial cutting transverse curved blade 51 and an outer peripheral side lower linear blade 52 on one radial cutter holder (not shown), and is retracted by cutting a middle portion of the seal ring material 1s in the width w from the outer peripheral surface (100s) side of the seal ring material 1 s. Here, the outer peripheral lower linear blade 52 moves forward or backward along a straight line M passing through the machining reference point P and the axial center O of the seal ring material 1s shown in fig. 10.

The cutting edge 51a (double edge) of the radial cutting lateral curved blade 51 is formed in an arc shape (a curvature radius R shown in fig. 18 a) in which an intermediate portion of the cutting edge 51a is recessed in the blade back direction. That is, the arc (radius of curvature R) of the cutting edge 51a is the same as the arc (radius of curvature R) axially cut into the side surface of the cutting edge 42a of the curved blade 42, and the radii of curvature and the arc lengths of the cutting edge 51a and the cutting edge 42a are equal to each other. In addition, the edges 51b, 51d of the radially incising transverse curvilinear knife 51 are configured to: the joint of the seal ring material 1s is cut toward the axial center O of the seal ring material 1 s. Further, a lip 51c (double cutting edge) is formed at a lip 51d that cuts radially into the lateral curved blade 51 on the opposite side of the outer peripheral lower straight blade 52. The radial length of the radial cutting lateral curved blade 51 is such that the cutting edge 51a can reach the thickness direction middle cut surface 21 (see fig. 15B). The cutting position of the radial cutting lateral curved blade 51 is equal to the depth of the intermediate cutting into the cut surface 21 in the thickness direction, that is, a position at which the cutting edge 42a of the axial cutting curved blade 42 stops in the axial direction. Therefore, as shown in fig. 18 (a), when the radial incision traverse curve knife 51 performs incision, the widthwise intermediate incision cut surface 23 is formed, and the incision 12b is formed. Both circumferential ends of the widthwise middle cut surface 23 are formed as straight lines toward the axial center O of the seal ring material 1 s. In addition, the positions of the widthwise middle cut surfaces 23 are as follows: the position of the seal ring material 1s in the width w direction, which is located at the middle between the side surfaces in the axial direction, in the thickness t direction of the seal ring material 1s depends on the position of the cut surface 21 cut into the middle in the thickness direction.

As shown in fig. 17, when viewed from the outer peripheral surface 100s side, the slit 12b is seen to have a straight line shape parallel to the top surface 110s or the bottom surface 120s, and to be a projection straight line which is a straight line projected on the outer peripheral surface 100 s.

An outer peripheral lower linear blade 52 is integrally held in an L shape by a radial cutting blade holder (not shown) at an edge 51B of the radial cutting lateral curved blade 51, that is, at an edge 51B of a connecting portion between the thickness direction intermediate cut surface 21 and the thickness direction intermediate through cut surface 24 (see fig. 15B).

The cutting edge 52a (double edge) of the outer peripheral lower linear cutter 52 is formed by: the length is longer than the distance from the edge 51b to the bottom surface (120s) of the seal ring blank, and the position of the tip 52a at the radial front end of the seal ring blank 1s coincides with the position of the tip 51a at the front end. Therefore, as shown in fig. 18 (B), when the cutting edge 52a of the outer peripheral lower linear blade 52 cuts into the outer peripheral lower cut surface 25, the cut 12a and the cut 12c shown in fig. 5 are formed.

Fig. 17 is a front view of the seal ring material 1s shown in fig. 16, and shows a slit of a cut portion cut in the third step.

The view from the direction 6-6 and the view from the direction 7-7 in fig. 17 are shown in (a) and (B) in fig. 18.

Next, a fourth process of forming a joint by the outer peripheral upper linear blade 60 will be described with reference to fig. 19. At this time, the workpiece fixing and conveying unit 70 is moved to an outer peripheral side upper cutting unit position (not shown).

The outer peripheral upper linear cutter 60 is held by an outer peripheral upper cutter holder (not shown), attached to a high-precision fourth servo cylinder (not shown), and cut into and retracted from the outer peripheral side of the seal ring material 1s toward the axial center O of the seal ring material 1s at the tip end of the slit 12 b. Here, a fourth servo cylinder is attached to an index table (not shown) so as to cut the outer peripheral upper linear knife 60 into the axial center O of the seal ring material 1 s.

The 8-8 view in fig. 19 is shown in fig. 20.

The cutting edge 60a (double cutting edge) of the outer peripheral upper linear cutter 60 is formed by: the length is longer than the distance between the end portion of the width-direction intermediate cut surface 23 (see fig. 18 a) on the opposite side to the outer peripheral-side lower cut surface 25 (see fig. 18B) side in the circumferential direction and the top surface (110s) side of the seal ring material. Therefore, as shown in fig. 20, when the cutting edge 60a of the outer peripheral upper linear blade 60 is cut from the outer peripheral side, the outer peripheral upper cut surface 22 is formed, and the cuts 13a and 13b are also formed.

The seal ring material 1s after the outer peripheral upper portion cut into the cut surface 22 is formed at the outer peripheral upper cutting means position, and becomes the seal ring 1 in which the seam cut portion 1a is formed. Then, as a fifth step, at the workpiece discharge position (refer to a workpiece discharge position 205 of fig. 21 described later), the ring top surface pressing member 73 is raised from the state shown in fig. 12, and the positioning member (movable side) 71 is moved by the first servo cylinder (not shown) to be separated from the inner peripheral surface 130 of the seal ring, thereby releasing the seal ring 1 from the clamped state. Thereby, the seal ring material 1s is formed into the seal ring 1 and taken out from the work fixing and conveying unit 70.

The seam-cut portion 1a is formed by the above-described operation, and the seal ring 1 is separated by the seam-cut portion 1 a. When the cutting surface is formed, the seal ring material 1s is pushed open by the cutting edge of the cutting blade by an amount corresponding to the thickness of the cutting edge. In this case, it is preferable to reduce the thickness of the cutting blade and to form the cutting edge into two blades so that the amount of pinching-off on both sides of the cutting edge is uniform and small.

As described above, in this joint machining method, the seal ring material 1s is clamped in a state where the joint forming portion of the seal ring is not deformed, and the seal ring material 1s is moved to each cutting unit while maintaining the same posture on the horizontal machining table, first, the axial cutter 40 is caused to cut into the seal ring material 1s from one axial side at the axial cutting unit to perform cutting, then, the radial cutter 50 is caused to cut into the seal ring material 1s from the outer peripheral side at the radial cutting unit to perform cutting, and further, the outer peripheral side upper linear cutter 60 is caused to cut into the seal ring material 1s at the outer peripheral side upper cutting unit to perform cutting, so that there is no need to change the posture of the seal ring material 1s depending on the machining process. Therefore, the cut surface of the seam cut part 1a can be formed with high accuracy.

In the present embodiment, as an example, a mode in which the seal ring material 1s is sequentially linearly moved to each cutting unit provided with a cutter holder by the work fixing and conveying unit and seam cutting processing is performed is shown.

(modification example)

As another example of the embodiment, by arranging five workpiece fixing and conveying units on the index table by using the rotary index table and arranging three cutting units outside the rotary index table in a concentric circle with the index table, the time for cutting the joint of each seal ring can be set to 10 seconds or less.

Fig. 21 is a schematic plan view showing a seam processing apparatus 200 according to an embodiment of the modification. In this seam processing apparatus 200, a workpiece fixing and conveying unit 70 is attached to a rotating disc-shaped rotary index table 200a, and the workpiece fixing and conveying unit 70 rotates in accordance with the rotation of the rotary index table 200 a. By this rotation, the seal ring material 1s is machined at the joint cutting portion 1a by moving from the workpiece receiving position 201 to the axial direction cutting unit position 202, the radial direction cutting unit position 203, the outer peripheral side upper portion cutting unit position 204, and the workpiece discharge position 205 in this order.

That is, at the work receiving position 201, the seal ring material 1s as a work is clamped and fixed by the work fixing and conveying unit 70. The seal ring material 1s is fixed by the following method: after the seal ring material 1s is placed on the machining table 70a, a positioning member (movable side) (reference numeral 71 in fig. 10, 11, 12, and 13) fixed to the first servo cylinder 75 is moved to a position where it contacts the inner peripheral surface of the seal ring material 1s to position the seal ring material 1s, and then a ring top surface pressing member (fixing member) attached to the cylinder is lowered to press the top surface of the seal ring material 1s, thereby fixing the seal ring material 1 s. The workpiece fixing and conveying unit 70 holding the seal ring material 1s is rotationally moved to the axial cutting unit position 202 by the rotation of the rotary index table 200 a.

When located at the axial cutting unit position 202, the axial cutter holder 211 is lowered from above, thereby forming the thickness direction intermediate cut-in surface 21, the thickness direction intermediate through cut surface 24, and the inner peripheral side cut surface 26 on the seal ring blank 1s as shown in fig. 14 and 15. Then, the axial cutter holder 211 is lifted up and separated from the seal ring material 1s, and the work fixing and conveying unit 70 is rotationally moved to the radial cutter unit position 203 by the rotation of the rotary index table 200 a.

At the radial cutting unit position 203, the radial cutting knife holder 212 is advanced in the radial direction from the outer peripheral side of the seal ring blank 1s, thereby forming the widthwise-intermediate cut-in surface 23 and the outer-peripheral-side lower cut-in surface 25 as shown in fig. 17 and 18. Then, the axial cutter holder 212 is retracted to be separated from the seal ring material 1s, and the workpiece fixing and conveying unit 70 is rotationally moved to the outer peripheral upper cutting unit position 204 by the rotation of the rotary index table 200 a.

At the outer peripheral side upper cutting unit position 204, the outer peripheral side upper cutting knife holder 213 is advanced radially from the outer peripheral side of the seal ring blank 1s, thereby forming the outer peripheral side upper cut-in cut surface 22 as shown in fig. 19 and 20. Then, the outer peripheral upper cutter holder 213 retreats and is separated from the seal ring material 1s, and the workpiece fixing and conveying unit 70 is rotationally moved to the workpiece discharge position 205 by the rotation of the rotary index table 200 a. At this time, the forming process for forming the seam-cut portion 1a in the seal ring material 1s is completed.

At the work discharge position 205, the seal ring blank 1s is released from the clamping by the work fixing-and-conveying unit 70. Next, the seal ring 1 on which the seam-cut portion 1a is formed is taken out from the workpiece fixing and conveying unit 70.

Claims (3)

1. A joint processing method of a sealing ring is characterized by comprising the following steps:

a first step: clamping the seal ring blank at a predetermined position by a work fixing and conveying unit, wherein the work fixing and conveying unit comprises: a processing table for seam cutting on which a ring-shaped seal ring blank made of synthetic resin is placed so as to be axially perpendicular to the processing table; a pair of half disc-shaped positioning members which are in contact with mutually opposing portions of the inner peripheral surface of the seal ring material, and have a radius of curvature equal to or smaller than the radius of curvature of the inner peripheral surface of the seal ring material; a first servo cylinder for moving a half disc-shaped positioning member located at a position facing the seam forming part, among the half disc-shaped positioning members; a fixing member that presses at least two portions of a top surface of the seal ring material, which is the other side surface of the seal ring material, between which a seam-forming portion is circumferentially interposed, and a portion that is radially opposed to the seam-forming portion, against a bottom surface of the seal ring material, which is the side surface of the seal ring material that is in contact with the surface of the machining table; and a cylinder for mounting the fixing member and moving the fixing member forward or backward with respect to the surface of the processing table;

a second step: after maintaining the state in which the seal ring material is clamped at the predetermined position by the workpiece fixing and conveying unit in the first step and moving to an axial cutting unit position provided with a second servo cylinder to which an axial cutter holder is attached, the axial cutter holder is moved forward or backward from above in the vertical direction of the machining table by the second servo cylinder, thereby forming a substantially L-shaped cut surface composed of an arc-shaped cut surface and a linear cut surface on the top surface of the seam forming portion of the seal ring material; wherein the circular arc-shaped cutting surface is a circular arc concentric with the inner peripheral surface of the seal ring blank and extending in the circumferential direction, a central angle formed by both ends of the circular arc and the axial center of the seal ring blank is 2 α, and a central angle between a position where the inner peripheral surface of the seam forming portion of the seal ring blank contacts with the semicircular portion of the semi-disc-shaped positioning member and an end of the circular arc is α; the linear cut surface extends from one end in the circumferential direction of the arc-shaped cut surface toward the inner circumferential side and the axial center of the seal ring blank;

a third step: after the first step of maintaining the state in which the seal ring material is clamped at the predetermined position by the work fixing and conveying unit, the seal ring material is moved to a radial cutting unit position having a third servo cylinder to which a radial cutter holder is attached by the second step, and the radial cutter holder is moved forward or backward in a direction from an outer side of an outer peripheral surface of the seal ring material toward the outer peripheral surface by the third servo cylinder, thereby forming a cut surface having an L-shaped projection shape on the outer peripheral surface on a seam forming portion of the seal ring material; wherein, this "L" word form cutting plane includes: a cutting surface projected on the outer peripheral surface of the seam-forming portion of the seal ring material as a projected straight line parallel to the top surface or the bottom surface of the seal ring material, wherein a central angle formed by both ends of the projected straight line in a plane including the projected straight line and perpendicular to the axial direction is α, one end of the projected straight line is located at a position where the inner peripheral surface of the seam-forming portion of the seal ring material contacts the semicircular portion of the semi-disc-shaped positioning member on a straight line passing through one end of an arc formed on the top surface of the seal ring material in the second step and concentric with the inner peripheral surface of the seal ring material and extending in the radial direction; and a linear cut surface extending from the position of the other end of the projected straight line toward the bottom surface side;

a fourth step: after moving to an outer peripheral side upper cutting unit position including a fourth servo cylinder to which an outer peripheral side upper linear knife holder is attached and an index table that controls a cutting direction of an outer peripheral side upper linear knife through the second step and the third step while maintaining a state in which the seal ring material is clamped at a predetermined position by the work fixing and conveying unit in the first step, the outer peripheral side upper cutting knife holder is advanced or retracted by the fourth servo cylinder in a direction from an outer side of an outer peripheral surface of the seal ring material toward the outer peripheral surface, thereby forming a linear cut surface extending from one end of the projection line that is formed on the outer peripheral surface of the seal ring material in the third step and is parallel to a top surface or a bottom surface of the seal ring material toward the top surface side; and

a fifth step: after forming a joint in the annular seal ring material through the second to fourth steps, the work fixing and conveying unit, which is continuously maintained in a state of holding the seal ring material at a predetermined position, is moved, the fixing member pressing the seal ring material is retreated upward by the air cylinder, and the positioning member located at a position opposite to the joint forming portion is retreated toward the joint forming portion side by the first servo air cylinder, so that the seal ring formed by forming a joint in the seal ring material is taken out.

2. The seam processing method according to claim 1,

the rotary indexing table is provided with more than five workpiece fixing and conveying units, and the sealing ring blank is conveyed to three cutting units in sequence.

3. A seam cutter for a seal ring, which is made of metal, characterized in that, based on the seam processing method for a seal ring according to claim 1 or 2, an axial cutter, a radial cutter and an upper linear cutter on the outer peripheral side are used in sequence to form a seam on a seal ring blank which is made of synthetic resin and is in a ring shape;

the axial cutting knife comprises an axial through curve knife, an axial cut-in curve knife and an inner peripheral side straight line knife, and is cut in along the direction parallel to the axial direction of the sealing ring blank, so that a middle through cutting surface in the thickness direction is formed by the axial through curve knife, a middle cut-in cutting surface in the thickness direction is formed by the axial cut-in curve knife, and an inner peripheral side cutting surface is formed by the inner peripheral side straight line knife; wherein the axial penetration curve cutter penetrates the width of the seal ring blank along the direction parallel to the axial direction of the seal ring blank at the middle part of the seal ring blank in the thickness direction, and is in an arc shape concentric with the inner circumferential surface of the seal ring blank, and the thickness direction of the seal ring blank is along the radial direction of the seal ring blank; the axial direction cutting curve knife is in a circular arc shape concentric with the inner circumferential surface of the sealing ring blank, extends along the circumferential direction from one end of the axial direction cutting curve knife, and forms a notch reaching the middle of the width of the sealing ring blank along the axial direction; the inner peripheral side linear knife is connected with the other end of the axial through curved knife, the length of the inner peripheral side linear knife in the radial direction of the sealing ring blank is from the inner peripheral surface of the sealing ring blank to the axial through curved knife, and the inner peripheral side linear knife penetrates through the sealing ring blank in the axial direction;

the radial cutting knife comprises a radial cutting-in transverse curve knife and an outer periphery side lower linear knife, and cuts in from the outer side of the outer periphery surface of the sealing ring blank towards the axial center direction of the sealing ring blank, so that a width direction middle cutting-in cutting surface is formed by the radial cutting-in transverse curve knife, and an outer periphery side lower cutting-in cutting surface is formed by the outer periphery side lower linear knife; wherein the radial cut-in transverse curve knife cuts into the cutting surface from the outer peripheral surface of the seal ring blank to the middle in the thickness direction in the middle of the width of the seal ring blank, and the knife tip of the radial cut-in transverse curve knife is in an arc shape extending in the circumferential direction of the middle cut-in cutting surface in the thickness direction, and the length of the knife tip is equal to the length of the cutting surface in the circumferential direction of the middle cut-in cutting surface in the thickness direction; the outer periphery side lower linear knife is connected with one end of the radial cut-in transverse curve knife, and cuts into a connecting part between the middle penetration cutting surface in the thickness direction and the middle cut-in cutting surface in the thickness direction;

the outer peripheral side upper portion linear knife cuts from the outer side of the outer peripheral surface of the seal ring material toward the axial center direction of the seal ring material, and cuts the end portion of the cut surface along the width direction middle portion from the outer peripheral surface of the seal ring material to the end portion of the cut surface along the thickness direction middle portion, and cuts from the cut surface along the width direction middle portion to one end surface of the seal ring material in the axial direction, thereby forming an outer peripheral side upper portion cut surface;

the curvature radius and the arc length of the cutting edge of the radial cutting-in transverse curve cutter and the cutting edge of the axial cutting-in curve cutter are respectively set to be equal.

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