JPS634797B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cored braided packing for use in stuffing boxes of shaft-penetrating parts of valves, pumps, etc., and to improvements in its manufacturing method. Conventionally, this type of packing, which requires particularly heat resistance, has a core made of a molded body made of graphite and inorganic fibers such as asbestos fibers (generally called a thermocore), and a braided body surrounding the core. A structure coated with an outer skin is used. Moreover, the heat-resistant packing having the above structure is manufactured by the following method. (a) Add an organic binder such as resin or rubber to graphite and inorganic fibers such as asbestos fibers, extrude the mixture into a rod-shaped product with a square or circular cross section, and dry. (b) The extrusion-molded dried product is used as a core, and the periphery of the core is braided into a bag shape with inorganic fiber yarn such as asbestos. (c) To fill the gap between the core and the braided body,
Coating with an inorganic lubricant such as graphite using rubber, resin, etc. as a binder (referred to as surface treatment). (d) The core-containing braided body subjected to the surface treatment is pressed with two-point rollers to make it rectangular (referred to as flattening treatment).
do. (e) The flattened product is placed in a mold and pressure-molded into a ring shape with a square cross section. However, for the purpose of heat-resistant sealing, the amount of binder such as rubber or resin added to the packing made of the above-mentioned materials, which causes heat loss, is limited to a few percent or less of the entire packing. It has the following drawbacks. (a) Since the core is brittle and easily crumbles, it is not possible to construct a continuous manufacturing facility that integrates the core manufacturing process and the braided body covering process. (b) Stress relaxation during use is large and sealing performance is poor. (c) Carbonization of the binder such as rubber or resin causes the packing to harden into a ceramic-like shape, making it extremely difficult to remove the packing with a tool after use. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-resistant packing which eliminates the above-mentioned drawbacks and a method for manufacturing the same. The core-containing braided packing according to the present invention has expanded graphite sheets laminated and compressed in a direction parallel to the laminated surface to form the core, and the periphery of the core is covered with a braided body of inorganic fiber yarn. It is characterized by its structure. Furthermore, in the method for producing packing according to the present invention, a required number of long expanded graphite sheets are aligned and laminated while being guided to a braiding machine, and the braiding machine
The laminate is used as a core, the periphery of the laminate is covered with a braided body of inorganic fiber yarn, and the braided body containing the core is cut to a required length and placed in a mold to form a core. It is characterized by compressing the expanded graphite sheets in a direction parallel to the laminated surface and molding the entire sheet into a ring shape. The expanded graphite sheet used for the core of the packing is disclosed in, for example, Patent No. 574425 (Japanese Patent Publication No. 44-23966).
As disclosed in
A well-known graphite sheet is applied which has been expanded twice and compressed to a density of at least 80 Kg/m ³ . Hereinafter, the present invention will be explained based on drawings showing embodiments thereof. FIG. 1 shows an outline of a braiding machine for manufacturing packing according to the present invention. 1a, 1b, 1c, and 1d are bobbins for winding up table-shaped expanded graphite sheets 1, and these bobbins are prepared as many as the number of sheets to be laminated. Reference numeral 2a is a winding bobbin for the binding wire 2 for binding the sheet laminate, and for example, fine metal wire (wire diameter 0.1 to 0.2 mm) of copper, brass, Monel, or Inconel is used. 3 is a base plate that supports the bobbin 2a and rotates. 4a, 4b, 4c, and 4d are bobbins for winding inorganic fiber yarns 4 such as glass fiber yarns, metal-reinforced carbon fiber yarns, and boron fiber yarns, and these bobbins are prepared in equal numbers to the number of braided yarns to be braided. The spindle supporting each bobbin is moved in a fixed trajectory by a gear movement mechanism (not shown). 5 is a die plate, and 6 is a cap. In the above braiding machine, a required number of tape-shaped expanded graphite sheets 1 are pulled out from bobbins 1a to 1d.
are laminated while being passed through the rotary base plate 3, and at the outlet thereof, are tied in a spiral shape with a binding wire 2 at a required pitch, and guided to the base 6 of the die 5. On the other hand, a predetermined number of inorganic fiber threads 4 are pulled out from the bobbins 4a to 4d and passed through the cap 6.
is knitted in a bag around the sheet laminate at the base 6 by the movement of the bobbin support spindle, and at the outlet of the base 6, a braided packing A having the expanded graphite sheet laminate as a core is woven into a bag around the sheet laminate at the base 6. It is formed. FIG. 2 shows an enlarged perspective cross-sectional view of the core-containing braided packing A. That is, a laminate made of tape-shaped expanded graphite sheets 1 is laminated to have a rectangular cross section with the width of the tape as the long side a and the stacked thickness as the short side b for the purpose described later. The cored braided packing formed as described above is cut into the required length, placed in a mold, and pressed in a direction parallel to the laminated surface of the sheet laminate, as shown in Figure 3. Then, the sheet laminate is compressed so that its cross section becomes approximately square, and the whole is formed into a ring shape to produce a product. According to the above-mentioned method for manufacturing the core-containing braided packing, tape-shaped expanded graphite sheets are laminated to form the core, so the fragility of the expanded graphite sheet itself is greatly improved by the lamination effect of the sheets. As a result, a long core that is extremely easy to handle can be obtained, and the core forming step and the braid covering step can be performed in a continuous and integrated manner. In addition, by making the cross section of the expanded graphite sheet laminate rectangular in advance and then compressing it into a square, it is possible to omit the two-point roller application process when forming the cored braided body into a ring shape. . In addition, if a laminate of expanded graphite sheets is compressed and molded in a direction parallel to the laminated surface, the laminate sheet will flow and deform into a wave shape due to the unique orientation of the expanded graphite sheets. The gap between them is filled. This gap filling effect is related to the compression ratio of the laminate, that is, the a/b ratio of the laminate described above.The compression ratio is in the range of 1.5 to 3.0, preferably 2.0, and the higher the compression ratio, the better The gap is more completely filled. Therefore, a braided packing with no gaps can be obtained without coating with a processing agent of a graphite mixture containing rubber, resin, or the like as a binder. As a result, a molded body (density = 1.7 to 1.8) as dense as that of expanded graphite packing alone can be obtained.
It is possible to obtain a cored braided packing that exhibits significantly less stress relaxation and greatly improved sealing performance than conventional braided packing. Further, since the cored braided packing does not harden after use, it is easy to take it out of the stuff-in box. In the above embodiment, an example is shown in which the expanded graphite seal laminate is compressed from a rectangular cross section to a square cross section, but it can also be compressed from a square cross section to a rectangular cross section. In addition, when making a laminate of expanded graphite sheets,
Even if the sheets are not bound with a metal wire, if a cap is provided to collect and hold the sheets at the inlet to the braiding machine, substantially the same binding effect as the above-mentioned binding wire can be obtained. Next, examples of this invention will be shown below. Example 18 layers of graph oil sheets manufactured by Union Carbide in the United States with a thickness of 0.4 mm and a width of 15 mm were used as expanded graphite sheets, and the laminated body was heated at a speed of 3 to 6.
The copper wire is introduced into the rotary base plate (see Figure 1) at a rate of cm/sec, and the copper wire with a wire diameter of 0.2 mm set on the base plate at the outlet is wound with a pitch of 50 mm, and this is continuously passed through a well-known 16-batch double-knit braider. Tokyo Steel Co., Ltd.
SUS316-L stainless fiber roving (wire diameter 8μ, number of fibers 4000) 1 piece, weight 200g,
Bag knitting is performed with a gear ratio of top/bottom = 55/50, and this cored braid is cut into 18.8 mm pieces, inserted into a mold, and subjected to surface pressure from a direction parallel to the laminated surface of the laminate using a hydraulic press. Compressed at 600Kgf/ ^cm2 , outer diameter 70mm, inner diameter 50
A ring-shaped braided patch with a height of 10 mm and a height of 10 mm was obtained. Regarding the ring-shaped braided packing of the above embodiment,
The following tests were conducted. In addition, asbestos braided packings with the same dimensions were prepared as comparison specimens, and these two types of packings were tested under the same conditions as described below. As shown in FIG. 4, the braided packing A of the above embodiment and the asbestos braided packing (the drawings are omitted) are each arranged so that the valve stem 6 has a diameter of 50.0 mm and the stuffing box has an inner diameter of 50.0 mm.
Insert into the gland part 7 of the same type of valve of 70.4 mm, and insert four expanded graphite packings B of the same size as each packing into the gland part of each valve,
The packing A of the above-mentioned example and the asbestos braided packing of the comparison specimen were used as back-up links for a combination (combined packing) specimen with the four expanded graphite packings B. Each of the packings and stone braided packings of the above example was tightened with a surface pressure of 600 kgf/cm ² , and the valve was heated at 650°C.
Steam of 350Kgf/cm ² was introduced, and the outer wall of the stuffing box was heated to 650℃ using a heater to prevent the temperature of the gland from decreasing.
The above pattern of continuously venting the steam for 8 hours and stopping the ventilation for 16 hours was repeated a total of 5 times, and during each pattern, the valve stem was vibrated 20 times at a stroke of 200 mm and a speed of 700 mm/min, and slid a total of 100 times in all patterns. During this test, the amount of steam leakage was measured in the drain state,
The tightening pressure was measured using a dynamic strain meter → oscillograph. Table 1 shows the measurement results.

[Table] As shown in Table 1, the packing of the above example was found to be extremely superior to the conventional asbestos braided packing in all respects of stress relaxation rate and sealing performance. Furthermore, after the above test, the packing was removed using a commercially available packing tool, and as a result, the packing of the above example could be taken out in 20 minutes, but the asbestos braided packing could not be removed even after 60 minutes, and the packing was removed from the stuffing box. I was able to take it out by applying water pressure from the bottom. In the above embodiments, the core of the braided packing is shown as having only expanded graphite sheets laminated, but it is also possible to insert a wire mesh sheet between expanded graphite sheets and laminating this core. By using it, the strength of the expanded graphite sheet and the packing as a whole can be increased. The wire material of the wire mesh inserted between the expanded graphite sheets is preferably SUS304, SUS316, SUS321, Inconel, copper wire, etc., and the size is 0.05 to 0.3 in thickness.
It is suitable to use a wire rod with a diameter of 1 mm to 15 mm square. The core of the expanded graphite sheet containing the wire mesh sheet is placed between the winding bobbins 1a, 1b, 1c, and 1d of the tape-shaped expanded graphite sheet 1 in, for example, the manufacturing apparatus for braided packing with core shown in FIG. By arranging a winding bobbin of shaped wire mesh sheets and taking a means to draw them together and send them out,
In a series of manufacturing processes for braided packing, it is extremely easy to obtain without requiring any special equipment. The braided packing manufactured using the expanded graphite sheet with wire mesh as the core is press-formed in the direction parallel to the laminated surface of the sheet laminate, as in the above embodiment, but the core is made of expanded graphite sheet only. Compared to the case of pressurization, the expanded graphite sheet containing the wire mesh sheet is compressed more and its density is increased, so the ratio of the width a of the expanded graphite sheet used to the laminated thickness b is such that the reinforcing wire mesh sheet is not used. It may be slightly smaller than the actual case. In the case of a braided packing whose core is an expanded graphite sheet containing a wire mesh, the following effects can be obtained in addition to the braided packing whose core is an expanded graphite sheet. (1) The bending strength, tensile strength, and tear strength of the laminated tape-shaped expanded graphite sheet are greatly improved by pressure bonding with the wire mesh sheet, and the sheet is used in the sheet feeding process, braiding process, and winding process. Eliminates product defects due to cuts and bends. (2) Since the molded product of braided packing has a wire mesh sheet in its core, the strength of the entire packing is increased, and in particular, the durability of the opening (cut) of the packing against core blow-through is increased. (3) When loading a braided packing molded product into a stuffing box and opening the opening of the packing in order to wind it around a shaft, the packing's cross section deforms;
The degree of deformation is less than when no reinforcing wire mesh sheet is used. (4) If the overall strength of the braided packing is increased, it will be easier to remove it from the stuff-in box using a removal tool. As described above, according to the present invention, a laminate of expanded graphite sheets compressed in a direction parallel to the laminate surface is used as the core, and a braided body of inorganic fiber yarn is coated around the core. Therefore, the unique orientation of the expanded graphite sheet is utilized, and a cored braided packing with excellent molding and sealing effects can be obtained. Further, according to the present invention, long expanded graphite sheets are aligned and stacked while being guided to a braiding machine, and in the braiding machine, the laminate is used as a core and the periphery thereof is covered with a braided body of inorganic fiber yarn. , it is cut to the required length, placed in a mold, compressed in a direction parallel to the laminated surface of the laminate, and molded as a whole into a ring shape, so the forming process of the core and the braiding are It becomes possible to perform continuous work consistent with the body covering process, and a cored braided packing with good sealing performance can be obtained at low cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an apparatus illustrating an example of the method for producing a cored braided packing of the present invention, Fig. 2 is a perspective view of the cored braided packing before compression, and Fig. 3 shows the packing after compression. The perspective view and FIG. 4 are configuration diagrams of a performance testing apparatus for cored braided packing. 1... Expanded graphite sheet, 1a to 1d... Bobbin, 2... Binding wire, 3... Base plate, 4... Inorganic fiber thread, 4a to 4d... Bobbin, 5... Dice plate, 6
...Case, A...Braided packing with inner core.

Claims (1)

[Claims] 1. Expanded graphite sheets are laminated and compressed in a direction parallel to the laminated surfaces to form a core, and the periphery thereof is covered with a braided body of inorganic fiber threads. Braided underwear with inner core. 2. The required number of long expanded graphite sheets are aligned and stacked while being guided to a braiding machine, and the braiding machine
The laminate is used as a core, the periphery of the laminate is covered with a braided body of inorganic fiber yarn, and the braided body containing the core is cut to a required length and placed in a mold to form a core. A method for manufacturing a braided packing with a core, characterized by compressing expanded graphite sheets in a direction parallel to the laminated surface and forming the entire body into a ring shape. 3 Laminate expanded graphite sheets so that the cross section is rectangular, guide this into a braiding machine, cover the periphery of the laminate with a braided body of inorganic fiber yarn, and cut the cored braided body to the required length. Claim 2, in which the expanded graphite sheet is cut and placed in a mold, and compressed by applying pressure in a direction parallel to the laminated surface of the expanded graphite sheet forming the core so that the laminated body becomes approximately square. A method for manufacturing braided packing with a core. 4 The ratio between the width of the expanded graphite sheet and the laminated thickness is 1.5.
3. The method for manufacturing a cored braided packing according to claim 3, wherein expanded graphite sheets are laminated to have a rectangular cross section in the range of 3.0 to 3.0.