Gland packing

Abstract

To provide a gland packing which can cope with various performance requirements and usages.SOLUTION: A gland packing that is an endless-annular gland packing includes such a pair of first spiral parts in which both axial ends of a cylindrical first knit braided material are respectively spirally wound and formed, such a first connection part as to be formed on an axial direction midway part of the first knit braided material, and connect the pair of the first spiral parts on the radial direction on one side of the gland packing, such a pair of second spiral parts that both axial direction ends of a cylindrical second knit braided material are respectively spirally wound and formed, and such second connection part as to be formed on axial direction midway part of the second knit braided material and connects the part of second spiral packing on the other direction in the radial direction of the gland packing, and at least one side of the pair of the second spiral parts is sandwiched between the pair of the first spiral parts.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a gland packing. [Background technology]

[0002] The gland packing described in Patent Document 1 is formed into an endless ring by compressing both axial ends of a tubular knitted fabric while they are wound together. This gland packing is deformed so as to extend radially when compressed axially in a packing box that surrounds the shaft of the fluid device. This deformation causes the outer and inner peripheral surfaces of the gland packing to function as sealing surfaces that are in close contact with the inner peripheral surface of the packing box and the outer peripheral surface of the shaft, respectively. This allows the gland packing to prevent the sealed fluid in the fluid device from leaking to the atmosphere. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-180663 A Summary of the Invention [Problem to be solved by the invention]

[0004] The endless annular gland packing has better sealing properties than the endless annular gland packing which is made by rolling a string-like packing material into a ring shape. For this reason, the endless annular gland packing is required to meet various performance requirements and applications. The present disclosure has been made in consideration of the above circumstances, and aims to provide a gland packing that can meet a variety of required performance and applications. [Means for solving the problem]

[0005] (1) The present disclosure relates to an endless annular gland packing comprising: a pair of first spiral portions formed by spirally winding both axial ends of a tubular first knit fabric, a first connecting portion formed in the middle of the axial direction of the first knit fabric and connecting the pair of first spiral portions on one radial side of the gland packing; a pair of second spiral portions formed by spirally winding both axial ends of a tubular second knit fabric, and a second connecting portion formed in the middle of the axial direction of the second knit fabric and connecting the pair of second spiral portions on the other radial side of the gland packing, wherein at least one of the pair of second spiral portions is sandwiched between the pair of first spiral portions.

[0006] According to the gland packing of the present disclosure, the first and second connecting parts arranged on both radial sides are made of different knitted fabrics (first and second knitted fabrics) and function as the sealing surfaces on the outer and inner sides of the gland packing. Therefore, in order to form the sealing surfaces according to the required performance and application, the materials of the first and second knitted fabrics can be individually selected, so that it is possible to meet a variety of required performance and applications.

[0007] (2) The gland packing of (1) further comprises a pair of third spiral portions formed by spirally winding both axial ends of a tubular third knit fabric, and a third connecting portion formed in the middle of the axial direction of the third knit fabric and connecting the pair of third spiral portions on one radial side, and it is preferable that the first connecting portion and the third connecting portion are arranged side by side in the axial direction of the gland packing, and one of the pair of second spiral portions is sandwiched between the pair of first spiral portions and the other of the pair of second spiral portions is sandwiched between the pair of third spiral portions.

[0008] In this case, the first connecting portion and the third connecting portion arranged in the axial direction on one radial side of the gland packing are made of different knitted fabrics (the first knitted fabric and the third knitted fabric) and function as a sealing surface on one radial side of the gland packing. Therefore, in order to form a sealing surface on one radial side according to the required performance and application, the materials of the first knitted fabric and the third knitted fabric can be individually selected, so that it is possible to respond to even more diverse required performance and applications.

[0009] (3) In the gland packing of (1) above, it is preferable that the pair of second spiral portions are sandwiched between the pair of first spiral portions in a state where they are arranged side by side in the axial direction of the gland packing. In this case, for example, an existing gland packing made of a single knitted fabric as shown in Patent Document 1 can be used as a pair of second spiral portions and a second connecting portion made of the second knitted fabric of the present disclosure, thereby reducing the manufacturing cost of the gland packing of the present disclosure.

[0010] (4) In the gland packing of (1) above, it is preferable that one of the pair of second spiral portions is sandwiched between a pair of the first spiral portions, and one of the pair of the first spiral portions is sandwiched between a pair of the second spiral portions. In this case, the pair of first spiral portions and the pair of second spiral portions sandwich each other, so that the first knitted fabric and the second knitted fabric can be firmly joined together. Effect of the Invention

[0011] The gland packing of the present disclosure can meet a variety of required performance and applications. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing a shaft seal device equipped with a gland packing. [Diagram 2] FIG. 2 is a perspective view showing the gland packing according to the first embodiment. [Diagram 3]FIG. 3 is an axial cross-sectional view of the gland packing. [Figure 4] FIG. 4 is a perspective view showing each knitted fabric before the gland packing is manufactured. [Diagram 5] FIG. 5 is a cross-sectional view showing each knitted fabric during the manufacture of the gland packing. [Figure 6] FIG. 6 is a perspective view, partly cut away, showing a state in which each knitted fabric is wound in a spiral shape during the manufacturing process of the gland packing. [Figure 7] FIG. 7 is a perspective view showing a part of a state in which the spirally wound knitted fabrics are combined during the manufacture of the gland packing. [Figure 8] FIG. 8 is a cross-sectional view showing a die for molding the gland packing. [Figure 9] FIG. 9 is an axial cross-sectional view of the gland packing according to the second embodiment. [Figure 10] FIG. 10 is an axial cross-sectional view of the gland packing according to the third embodiment. [Figure 11] FIG. 11 is an axial cross-sectional view of the gland packing according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. [Shaft sealing device] 1 is a cross-sectional view showing a shaft seal device equipped with a gland packing. The shaft seal device 1 is provided in fluid equipment such as a pump or a mixer, and prevents a sealed fluid in the fluid equipment from leaking to the outside. The fluid equipment includes a shaft 50 that rotates around an axis C or reciprocates in the direction of the axis C. In the fluid equipment of this embodiment, the axis C of the shaft 50 is arranged horizontally, but the axis C may also be arranged vertically.

[0014] The shaft seal device 1 includes a packing box 2, a tightening mechanism 3, and a plurality of gland packings 10. The packing box 2 surrounds a shaft 50. A plurality of screw holes 2b (only one is shown in FIG. 1) are formed at intervals in the circumferential direction in an end face 2a of the packing box 2 on one axial side. An annular stepped surface 2c extending radially and a circumferential surface 2d extending from the outer peripheral end of the stepped surface 2c to the end face 2a are formed on the inner circumference of the packing box 2. The circumferential surface 2d faces an outer peripheral surface 50a of the shaft 50 in the radial direction. An annular space S is formed between the circumferential surface 2d of the packing box 2 and the outer peripheral surface 50a of the shaft 50.

[0015] The gland packings 10 are arranged side by side in the axial direction in the annular space S. Each gland packing 10 provides a seal between a circumferential surface (outer sealed surface) 2d of the packing box 2 and an outer circumferential surface (inner sealed surface) 50a of the shaft 50. The gland packings 10 will be described in detail later.

[0016] The tightening mechanism 3 is a mechanism for axially pressing a plurality of gland packings 10 arranged in the annular space S. The tightening mechanism 3 of this embodiment has a packing gland 4 and a bolt 5. The packing gland 4 has a cylindrical portion 4a provided radially outside the shaft 50 and an annular flange portion 4b. The other axial end of the cylindrical portion 4a is arranged in the annular space S. One axial end of the cylindrical portion 4a protrudes toward one axial side beyond the end face 2a of the packing box 2. The flange portion 4b extends radially outward from one axial end of the cylindrical portion 4a. The flange portion 4b has a plurality of insertion holes 4c (only one is shown in FIG. 1) formed in the circumferential direction and penetrating the flange portion 4b in the axial direction. A bolt 5 is inserted into each insertion hole 4c of the flange portion 4b.

[0017] The bolt 5 inserted into the insertion hole 4c is screwed into the screw hole 2b of the packing box 2. By tightening the bolt 5, the packing gland 4 moves to the other axial side relative to the packing box 2. Then, the gland packings 10 are pressed from both axial sides by the step surface 2c and the end face on one axial side of the cylindrical portion 4a. When each gland packing 10 is pressed in this manner, the outer peripheral surface 10a and the inner peripheral surface 10b of each gland packing 10 are brought into close contact with the circumferential surface 2d of the packing box 2 and the outer peripheral surface 50a of the shaft 50, which are radially opposed to each other, respectively, and function as a sealing surface. As a result, each gland packing 10 suppresses leakage of the sealed fluid in the fluid equipment to one axial side (atmosphere side).

[0018] [First embodiment] <Gland packing configuration> Fig. 2 is a perspective view showing a gland packing 10 according to the first embodiment. Fig. 3 is an axial cross-sectional view of the gland packing 10. The gland packing 10 is formed in an endless annular shape. The cross-sectional shape of the gland packing 10 shown in Fig. 3 is, for example, a rectangular shape that is long in the axial direction. The gland packing 10 of this embodiment is composed of a first knitted fabric 11, a second knitted fabric 12, and a third knitted fabric 13.

[0019] Each of the knitted fabrics 11, 12, and 13 is made by knitting yarn, and is formed into a cylindrical shape before the gland packing 10 is manufactured (see FIG. 4). The material of the yarn is not particularly limited, and organic fibers, inorganic fibers, and metal fibers can be used. Examples of organic fibers include cotton, rayon, phenolic fibers, PTFE fibers, polynosic fibers, aramid fibers, PBO fibers, PBI fibers, PPS fibers, and PEEK fibers. Examples of inorganic fibers include carbon fibers, ceramic fibers, and glass fibers. Examples of metal fibers include stainless steel wires, Inconel wires, and Monel wires. The yarn may be made of a single fiber selected from these fibers, or two or more types of fibers may be used in combination. The yarn may be a single yarn or a bundled yarn.

[0020] Fig. 4 is a perspective view showing the knitted fabrics 11, 12, and 13 before the gland packing 10 is manufactured. Fig. 5 is a cross-sectional view showing the knitted fabrics 11, 12, and 13 during the manufacturing process of the gland packing 10. In Figs. 3 to 5, the gland packing 10 includes a pair of first spiral portions 111, 112 and a first connecting portion 113 formed by the first knitted fabric 11.

[0021] One of the first spiral portions 111 is formed in a ring shape by spirally winding one axial end 11a of the first knitted fabric 11 radially inward toward the other axial side. The other of the first spiral portions 112 is formed in a ring shape by spirally winding the other axial end 11b of the first knitted fabric 11 radially inward toward the one axial side. Each of the first spiral portions 111, 112 is formed in a ring shape as a whole. The pair of first spiral portions 111, 112 are each formed in a rectangular shape in a cross-sectional view and are separated from each other in the axial direction of the gland packing 10.

[0022] The first connecting portion 113 is formed in a cylindrical shape extending in the axial direction at an axially intermediate portion of the first knitted fabric 11. Both axial ends of the first connecting portion 113 are connected to the pair of first spiral portions 111, 112 on the outer circumferential side (one radial side) of the gland packing 10. In this way, the first connecting portion 113 connects the pair of first spiral portions 111, 112.

[0023] The gland packing 10 includes a pair of second spiral portions 121, 122 and a second connecting portion 123 formed by the second knit fabric 12. One of the second spiral portions 121 is formed by winding one axial end 12a of the second knit fabric 12 in a spiral shape radially outward toward the other axial side. The other of the second spiral portions 122 is formed by winding the other axial end 12b of the cylindrical second knit fabric 12 in a spiral shape radially outward toward the one axial side. Each of the second spiral portions 121, 122 is formed in an annular shape as a whole. The pair of second spiral portions 121, 122 are each formed in a rectangular shape in a cross-sectional view, and are separated from each other in the axial direction of the gland packing 10.

[0024] The second connecting portion 123 is formed in a cylindrical shape extending in the axial direction at an axially intermediate portion of the second knitted fabric 12. Both axial ends of the second connecting portion 123 are connected to the pair of second spiral portions 121, 122 on the inner circumferential side (the other radial side) of the gland packing 10. In this way, the second connecting portion 123 connects the pair of second spiral portions 121, 122.

[0025] The gland packing 10 includes a pair of third spiral portions 131, 132 and a third connecting portion 133 formed by the third knit fabric 13. One of the third spiral portions 131 is formed by winding one axial end 13a of the third knit fabric 13 in a spiral shape radially inward toward the other axial side. The other of the third spiral portions 132 is formed by winding the other axial end 13b of the third knit fabric 13 in a spiral shape radially inward toward the one axial side. Each of the third spiral portions 131, 132 is formed in an annular shape as a whole. The pair of third spiral portions 131, 132 are each formed in a rectangular shape in a cross-sectional view, and are separated from each other in the axial direction of the gland packing 10.

[0026] The third connecting portion 133 is formed in a cylindrical shape extending in the axial direction at an axially intermediate portion of the third knitted fabric 13. Both axial ends of the third connecting portion 133 are connected to the pair of third spiral portions 131, 132 on the outer circumferential side (the other radial side) of the gland packing 10. In this way, the third connecting portion 133 connects the pair of third spiral portions 131, 132.

[0027] 3, the pair of first spiral portions 111, 112 and the first connecting portion 113 are disposed on one axial side of the gland packing 10. The pair of third spiral portions 131, 132 and the third connecting portion 133 are disposed on the other axial side of the gland packing 10. The first spiral portion 112 and the third spiral portion 131 are disposed side by side in the axial direction of the gland packing 10. The first connecting portion 113 and the third connecting portion 133 are disposed side by side in the axial direction on the outer periphery side of the gland packing 10.

[0028] One of the second spiral portions 121 is sandwiched between the pair of first spiral portions 111, 112 radially inward of the first connecting portion 113. The other of the second spiral portions 122 is sandwiched between the pair of third spiral portions 131, 132 radially inward of the third connecting portion 133. The second connecting portion 123 is disposed adjacent to the first spiral portion 112 and the third spiral portion 131 radially inward of the gland packing 10.

[0029] The outer peripheral surface 113a of the first connecting portion 113 and the outer peripheral surface 133a of the third connecting portion 133 are flush with each other and constitute the outer peripheral surface 10a of the gland packing 10. In this embodiment, the area ratio of the outer peripheral surface 113a of the first connecting portion 113 to the outer peripheral surface 133a of the third connecting portion 133 in the outer peripheral surface 10a of the gland packing 10 is approximately 1:1. As described above, the outer peripheral surface 10a of the gland packing 10 functions as a sealing surface. Therefore, the sealing characteristics of the outer peripheral surface 10a of the gland packing 10 are determined by the materials of the outer peripheral surfaces 113a, 133a of the first connecting portion 113 and the third connecting portion 133, that is, the materials of the first knitted fabric 11 and the third knitted fabric 13.

[0030] The inner circumferential surface 111b of the first spiral portion 111, the inner circumferential surface 123b of the second connecting portion 123, and the inner circumferential surface 132b of the third spiral portion 132 are flush with each other and constitute the inner circumferential surface 10b of the gland packing 10. In this embodiment, the area ratio of the inner circumferential surface 111b of the first spiral portion 111, the inner circumferential surface 123b of the second connecting portion 123, and the inner circumferential surface 132b of the third spiral portion 132 in the inner circumferential surface 10b of the gland packing 10 is about 1:4:1. As described above, the inner circumferential surface 10b of the gland packing 10 functions as a sealing surface. Therefore, the sealing characteristics of the inner circumferential surface 10b of the gland packing 10 are governed by the material of the inner circumferential surface 123b of the second connecting portion 123, which has the highest area ratio, that is, the material of the second knitted fabric 12.

[0031] <Manufacturing method of gland packing> Fig. 6 is a perspective view showing a state in which the knitted fabrics 11, 12, and 13 are wound in a spiral shape during the manufacture of the gland packing 10. Fig. 7 is a perspective view showing a part of a state in which the knitted fabrics 11, 12, and 13 wound in a spiral shape are combined during the manufacture of the gland packing 10. In Figs. 4 to 7, when manufacturing the gland packing 10, first, an operator winds both axial ends of each of the knitted fabrics 11, 12, and 13 in a spiral shape, as shown in Fig. 5 from the state shown in Fig. 4.

[0032] Specifically, the worker spirally winds radially inward one axial end 11a, 13a and the other axial end 11b, 13b of the first knit fabric 11 and the third knit fabric 13. The worker spirally winds radially outward one axial end 12a and the other axial end 12b of the second knit fabric 12.

[0033] 6, a pair of first spiral portions 111, 112 and a first connecting portion 113 are formed in the first knitted fabric 11. A pair of second spiral portions 121, 122 and a second connecting portion 123 are formed in the second knitted fabric 12. A pair of third spiral portions 131, 132 and a third connecting portion 133 are formed in the third knitted fabric 13. At this point, each of the spiral portions 111, 112, 121, 122, 131, 132 is formed to have a circular shape in a cross-sectional view.

[0034] Next, as shown in Fig. 7, the worker combines the knitted fabrics 11, 12, and 13. Specifically, the worker inserts the second spiral portion 121 of the second knitted fabric 12 between the pair of first spiral portions 111, 112 from the radially inner side of the first knitted fabric 11. The worker also inserts the second spiral portion 122 of the second knitted fabric 12 between the pair of third spiral portions 131, 132 from the radially inner side of the third knitted fabric 13. In this way, the worker obtains an intermediate structure 20 in which the knitted fabrics 11, 12, and 13 are combined.

[0035] 8 is a cross-sectional view showing a mold 70 for molding the gland packing 10. The mold 70 includes a lower mold part 71 and an upper mold part 72. The lower mold part 71 is formed with a cylindrical molding hole 71a that opens on its upper surface. The upper mold part 72 is made of a cylinder and is formed to a size that allows it to be inserted into the molding hole 71a of the lower mold part 71. An operator uses the mold 70 to compression mold the intermediate component 20 into the gland packing 10.

[0036] Specifically, the worker inserts the intermediate component 20 into the molding hole 71a of the lower mold part 71, and then inserts the upper mold part 72. In FIG. 8, the intermediate component 20 is shown in a simplified form. In this state, the worker presses the upper mold part 72 from above using a pressing machine (not shown). As a result, the intermediate component 20 is compressed between the lower mold part 71 and the upper mold part 72, and the gland packing 10 shown in FIG. 2 and FIG. 3 is formed.

[0037] <Action and effect> According to the gland packing 10 of this embodiment, the first connecting portion 113 (third connecting portion 133) arranged on the outer periphery side and the second connecting portion 123 arranged on the inner periphery side are made of the first knit fabric 11 (third knit fabric 13) and the second knit fabric 12 which are different knit fabrics, and function as the sealing surfaces on the outer periphery side and the inner periphery side of the gland packing 10. Therefore, in order to form the sealing surfaces according to the required performance and application, the materials of the first knit fabric 11 (third knit fabric 13) and the second knit fabric 12 can be individually selected, so that it is possible to respond to a variety of required performance and applications.

[0038] For example, aramid fiber can be used as the yarn for the first knitted fabric 11 (third knitted fabric 13), and graphite-containing PTFE fiber can be used as the yarn for the second knitted fabric 12. Aramid fiber has high fiber strength, so it can prevent the outer periphery side (first connecting portion 113 or third connecting portion 133) of the gland packing 10 from protruding into the gap on the packing box 2 side. This is therefore effective when it is desired to prevent a decrease in the tightening force of the tightening mechanism 3. Graphite-containing PTFE fiber has good lubricity and compatibility, so it is effective when it is desired to obtain good heat generation characteristics on the inner periphery side (second connecting portion 123) of the gland packing 10.

[0039] Also, carbon fiber impregnated with PTFE resin can be used as the yarn for the first knitted fabric 11 (third knitted fabric 13), and carbon fiber impregnated with PTFE resin and lubricating oil can be used as the yarn for the second knitted fabric 12. In this way, lubricating oil is contained only on the inner periphery of the gland packing 10, which is the sliding part that requires lubrication, and this is effective when it is desired to improve the stress relaxation characteristics of the entire gland packing 10.

[0040] The first connecting portion 113 and the third connecting portion 133, which are arranged in the axial direction on the outer periphery of the gland packing 10, are made of the first knitted fabric 11 and the third knitted fabric 13 which are different from each other, and function as a sealing surface on the outer periphery of the gland packing 10. Therefore, in order to form a sealing surface on the outer periphery according to the required performance and application, the materials of the first knitted fabric 11 and the third knitted fabric 13 can be individually selected, so that it is possible to respond to an even more diverse range of required performance and applications.

[0041] For example, a material with low permeation leakage can be used as the yarn for the first knitted fabric 11, and a material with low surface leakage can be used as the yarn for the second knitted fabric 12. This combination of materials is effective when it is desired to simultaneously suppress permeation leakage on one axial side (atmosphere side) and suppress surface leakage on the other axial side (machine interior side) on the outer periphery side of the gland packing 10.

[0042] In the gland packing 10 of this embodiment, the axial positions of the first knitted fabric 11 and the third knitted fabric 13 may be reversed. That is, the third knitted fabric 13 may be located on one axial side of the gland packing 10, and the first knitted fabric 11 may be located on the other axial side of the gland packing 10.

[0043] [Second embodiment] 9 is an axial cross-sectional view of the gland packing 10 according to the second embodiment. The gland packing 10 of this embodiment differs from the first embodiment in that the radial positions of the connecting portions 113, 123, and 133 are opposite to those of the first embodiment. In this embodiment, the pair of first spiral portions 111 and 112 are formed by winding both axial ends of the first knitted fabric 11 in a spiral shape radially outward. Both axial ends of the first connecting portion 113 are connected to the pair of first spiral portions 111 and 112 on the inner peripheral side of the gland packing 10.

[0044] The pair of second spiral portions 121, 122 are formed by winding both axial ends of the second knit fabric 12 in a spiral shape radially inward. Both axial ends of the second connecting portion 123 are connected to the pair of second spiral portions 121, 122 on the outer periphery side of the gland packing 10. The pair of third spiral portions 131, 132 are formed by winding both axial ends of the second knit fabric 12 in a spiral shape radially outward. Both axial ends of the third connecting portion 133 are connected to the pair of third spiral portions 131, 132 on the inner periphery side of the gland packing 10.

[0045] The outer circumferential surface 111a of the first spiral portion 111, the outer circumferential surface 123a of the second connecting portion 123, and the outer circumferential surface 132a of the third spiral portion 132 are flush with each other and constitute the outer circumferential surface 10a of the gland packing 10. In this embodiment, the area ratio of the outer circumferential surface 111a of the first spiral portion 111 to the outer circumferential surface 123a of the second connecting portion 123 and the outer circumferential surface 132a of the third spiral portion 132 in the outer circumferential surface 10a of the gland packing 10 is approximately 1:4:1. Therefore, the sealing characteristics of the outer circumferential surface 10a of the gland packing 10 are governed by the material of the outer circumferential surface 123a of the second connecting portion 123, which has the highest area ratio, that is, the material of the second knitted fabric 12.

[0046] The first connecting portion 113 and the third connecting portion 133 are arranged side by side in the axial direction on the radially inner side of the gland packing 10. The inner peripheral surface 113b of the first connecting portion 113 and the inner peripheral surface 133b of the third connecting portion 133 are flush with each other and constitute the inner peripheral surface 10b of the gland packing 10. In this embodiment, the area ratio of the inner peripheral surface 113b of the first connecting portion 113 to the inner peripheral surface 133b of the third connecting portion 133 in the inner peripheral surface 10b of the gland packing 10 is about 1:1. Therefore, the sealing characteristics of the inner peripheral surface 10b of the gland packing 10 are determined by the materials of the inner peripheral surfaces 113b, 133b of the first connecting portion 113 and the third connecting portion 133, that is, the materials of the first knitted fabric 11 and the third knitted fabric 13.

[0047] Other configurations of this embodiment are the same as those of the first embodiment, so the same reference numerals are used and the description thereof is omitted. In the gland packing 10 of the second embodiment, the axial positions of the first knitted fabric 11 and the third knitted fabric 13 may be reversed.

[0048] According to the gland packing 10 of this embodiment, the second connecting portion 123 arranged on the outer periphery side and the first connecting portion 113 (third connecting portion 133) arranged on the inner periphery side are made of the second knit fabric 12 and the first knit fabric 11 (third knit fabric 13), which are different knit fabrics, and function as the sealing surfaces on the outer periphery side and the inner periphery side of the gland packing 10. Therefore, in order to form the sealing surfaces according to the required performance and application, the materials of the second knit fabric 12 and the first knit fabric 11 (third knit fabric 13) can be individually selected, so that it is possible to respond to a variety of required performance and applications.

[0049] For example, graphite-containing PTFE fiber can be used as the yarn for the second knitted fabric 12, and aramid fiber can be used as the yarn for the first knitted fabric 11. The graphite-containing PTFE fiber has good conformability and is effective when it is desired to reduce the contact surface leakage on the outer circumferential side (second connecting portion 123) of the gland packing 10. The aramid fiber has high fiber strength and is effective when it is desired to improve the wear resistance of the inner circumferential side (first connecting portion 113) which is the sliding portion of the gland packing 10.

[0050] The first connecting portion 113 and the third connecting portion 133, which are aligned in the axial direction on the inner periphery side of the gland packing 10, are made of the first knitted fabric 11 and the third knitted fabric 13 which are different from each other, and function as the sealing surface on the inner periphery side of the gland packing 10. Therefore, in order to form the sealing surface on the inner periphery side according to the required performance and application, the materials of the first knitted fabric 11 and the third knitted fabric 13 can be individually selected, so that it is possible to respond to an even more diverse range of required performance and applications.

[0051] [Third embodiment] 10 is an axial cross-sectional view of the gland packing 10 according to the third embodiment. The gland packing 10 of this embodiment is different from the first embodiment in that it is composed of a first knitted fabric 11 and a second knitted fabric 12. A pair of second spiral portions 121, 122 in the second knitted fabric 12 of this embodiment are arranged side by side in the axial direction of the gland packing 10. The pair of second spiral portions 121, 122 are sandwiched between the pair of first spiral portions 111, 112 radially inward of the first connecting portion 113.

[0052] The outer peripheral surface 113a of the first connecting portion 113 extends over the entire axial direction of the gland packing 10 and constitutes the outer peripheral surface 10a of the gland packing 10. Therefore, the sealing characteristics of the outer peripheral surface 10a of the gland packing 10 are determined by the material of the outer peripheral surface 113a of the first connecting portion 113, i.e., the material of the first knitted fabric 11.

[0053] The inner circumferential surface 111b of the first spiral portion 111, the inner circumferential surface 123b of the second connecting portion 123, and the inner circumferential surface 112b of the first spiral portion 112 are flush with each other and form the inner circumferential surface 10b of the gland packing 10. In this embodiment, the area ratio of the inner circumferential surface 111b of the first spiral portion 111, the inner circumferential surface 123b of the second connecting portion 123, and the inner circumferential surface 112b of the first spiral portion 112 in the inner circumferential surface 10b of the gland packing 10 is about 1:2:1. Therefore, the sealing characteristics of the inner circumferential surface 10b of the gland packing 10 are governed by the material of the inner circumferential surface 123b of the second connecting portion 123, which has the highest area ratio, that is, the material of the second knitted fabric 12.

[0054] Other configurations of this embodiment are the same as those of the first embodiment, so the same reference numerals are used and the description thereof is omitted. The first connecting portion 113 and the second connecting portion 123 of the third embodiment may be formed so that their radial positions are reversed. In that case, the second connecting portion 123 is located on the outer periphery side of the gland packing 10, and the first connecting portion 113 is located on the inner periphery side of the gland packing 10. Therefore, the sealing characteristics of the outer periphery surface 10a of the gland packing 10 are governed by the material of the second knitted fabric 12 (the second connecting portion 123). Moreover, the sealing characteristics of the inner periphery surface 10b of the gland packing 10 are governed by the material of the first knitted fabric 11 (the first connecting portion 113).

[0055] In the gland packing 10 of this embodiment, the first connecting portion 113 and the second connecting portion 123 arranged on the outer circumferential side and the inner circumferential side, respectively, are made of the first knitted fabric 11 and the second knitted fabric 12 which are different from each other, and function as the sealing surfaces on the outer circumferential side and the inner circumferential side of the gland packing 10. Therefore, in order to form the sealing surfaces according to the required performance and application, the materials of the first knitted fabric 11 and the second knitted fabric 12 can be individually selected, so that it is possible to respond to a variety of required performance and applications.

[0056] In addition, the pair of second spiral portions 121, 122 and the second connecting portion 123 made of the second knitted fabric 12 of this embodiment can be made of an existing gland packing made of a single knitted fabric, for example, as shown in the above-mentioned Patent Document 1. This can reduce the manufacturing cost of the gland packing 10 of this embodiment.

[0057] [Fourth embodiment] 11 is an axial cross-sectional view of the gland packing 10 according to the fourth embodiment. The gland packing 10 of the present embodiment is a modified example of the third embodiment. In this embodiment, one second spiral portion 121 is sandwiched between a pair of first spiral portions 111, 112. In addition, one first spiral portion 112 is sandwiched between a pair of second spiral portions 121, 122.

[0058] The outer peripheral surface 113a of the first connecting portion 113 and the outer peripheral surface 122a of the second spiral portion 122 are flush with each other and form the outer peripheral surface 10a of the gland packing 10. In this embodiment, the area ratio of the outer peripheral surface 113a of the first connecting portion 113 to the outer peripheral surface 122a of the second spiral portion 122 in the outer peripheral surface 10a of the gland packing 10 is about 3:1. Therefore, the sealing characteristics of the outer peripheral surface 10a of the gland packing 10 are governed by the material of the outer peripheral surface 113a of the first connecting portion 113, which has a higher area ratio, i.e., the material of the first knitted fabric 11.

[0059] The inner circumferential surface 111b of the first spiral portion 111 and the inner circumferential surface 123b of the second connecting portion 123 are flush with each other and form the inner circumferential surface 10b of the gland packing 10. In this embodiment, the area ratio of the inner circumferential surface 111b of the first spiral portion 111 to the inner circumferential surface 123b of the second connecting portion 123 in the inner circumferential surface 10b of the gland packing 10 is about 1:3. Therefore, the sealing characteristics of the inner circumferential surface 10b of the gland packing 10 are governed by the material of the inner circumferential surface 123b of the second connecting portion 123, which has a higher area ratio, that is, the material of the second knitted fabric 12.

[0060] Other configurations of this embodiment are similar to those of the first embodiment, so the same reference numerals are used and the description thereof is omitted. In the gland packing 10 of the fourth embodiment, the first connecting portion 113 and the second connecting portion 123 may be formed so that their radial positions are reversed. In addition, the axial positions of the first knitted fabric 11 and the second knitted fabric 12 may be reversed.

[0061] In the gland packing 10 of this embodiment, the first connecting portion 113 and the second connecting portion 123 arranged on the outer circumferential side and the inner circumferential side, respectively, are made of the first knitted fabric 11 and the second knitted fabric 12 which are different from each other, and function as the sealing surfaces on the outer circumferential side and the inner circumferential side of the gland packing 10. Therefore, in order to form the sealing surfaces according to the required performance and application, the materials of the first knitted fabric 11 and the second knitted fabric 12 can be individually selected, so that it is possible to respond to a variety of required performance and applications.

[0062] Furthermore, the pair of first spiral portions 111, 112 and the pair of second spiral portions 121, 122 are sandwiched between each other, so that the first knitted fabric 11 and the second knitted fabric 12 can be firmly joined together.

[0063] [others] The number of turns of each of the spiral portions 111, 112, 121, 122, 131, and 132 in each of the above embodiments is not particularly limited. For example, a pair of spiral portions in each knitted fabric may have different numbers of turns. In addition, the number of turns of the spiral portion may be changed for each of a plurality of knitted fabrics made of different materials.

[0064] In each of the above embodiments, the same material may be used for the multiple knitted fabrics constituting the gland packing 10. For example, in the first and second embodiments, the same material may be used for all the knitting yarns of the multiple knitted fabrics 11, 12, and 13. Similarly, in the third and fourth embodiments, the same material may be used for all the knitted yarns of the multiple knitted fabrics 11 and 12.

[0065] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope of the claims and the meaning equivalent thereto. [Explanation of symbols]

[0066] 10 Gland packing 11 First knit 12 Second knitting 13 3rd knitting 111,112 First spiral section 113 1st connection part 121,122 Second spiral section 123 2nd connection part 131,132 Third volute 133 Third connection part

Claims

1. An endless annular gland packing, A pair of first spiral portions formed by winding both axial ends of a tubular first knitted fabric in a spiral shape, a first connecting portion formed in an axially intermediate portion of the first knitted fabric and connecting a pair of the first spiral portions on one radial side of the gland packing; A pair of second spiral portions formed by winding both axial ends of a tubular second knitted fabric in a spiral shape, a second connecting portion formed in an axially intermediate portion of the second knitted fabric and connecting the pair of second spiral portions on the other radial side of the gland packing; At least one of the pair of second spiral portions is sandwiched between the pair of first spiral portions.

2. A pair of third spiral portions formed by winding both axial ends of a tubular third knitted fabric in a spiral shape, A third connecting portion is formed in an axial middle portion of the third knitted fabric and connects a pair of the third spiral portions on one radial side. The first connecting portion and the third connecting portion are arranged side by side in an axial direction of the gland packing, One of the pair of second spiral portions is sandwiched between the pair of first spiral portions, The gland packing according to claim 1 , wherein the other of the pair of second spiral portions is sandwiched between the pair of third spiral portions.

3. The gland packing according to claim 1 , wherein the pair of second spiral portions are sandwiched between the pair of first spiral portions in a state where they are arranged side by side in the axial direction of the gland packing.

4. One of the pair of second spiral portions is sandwiched between the pair of first spiral portions, The gland packing according to claim 1 , wherein one of the pair of first spiral portions is sandwiched between the pair of second spiral portions.

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