JPH036369B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a sliding member having self-lubricating properties. Here, the sliding member refers to bearings such as sliding plates and bushes that are used in machines, equipment, structures, etc. that receive loads and slips, or contact-type packings that require a sealing function in addition to these functions. This includes stickers such as. Conventionally, sliding parts used in applications where it is difficult or undesirable to apply lubricants such as oil or grease to sliding surfaces include (i) base metals made of cast iron, copper alloys, or stainless steel castings; Holes and grooves are drilled in the hole and grooves, and these holes and grooves are filled with a solid lubricant such as graphite, molybdenum disulfide, or polytetrafluoroethylene resin (PTFE). (ii) A large amount of solid lubricant is arranged. (iii) A sintered alloy (sometimes referred to as a ``cermet'') (iii) A woven fabric made of a combination of PTFE fibers and other fibers is bonded to a substrate using an adhesive or bonded together by other means. It is known that the two are combined together. Here, with the sliding member according to (i), not only is it time-consuming to drill holes and cut grooves, and embedding and filling the solid lubricant is also troublesome, but the filled solid lubricant often falls off. There have been problems in that the lubrication function is hindered by this, or a good lubrication effect cannot be obtained when the sliding distance is short. The sliding member according to (ii) has an unsolved problem that when the blending ratio of solid lubricant increases, the mechanical strength of the sintered body, especially the impact strength and bending strength, is significantly impaired. . Another problem is that the manufacturing equipment is large-scale, making it unsuitable for high-mix, low-volume production. The sliding member according to (iii) has problems with the bonding method and its workability. In other words, in order to effectively utilize the low friction properties of RTFE, it is necessary to prevent the adhesive from seeping onto the surface of the mixed woven fabric as much as possible, and to ensure that the adhesive strength is uniform and there is no variation in the adhesive. However, this still poses quite difficult technical problems. Instead of using adhesives, attempts have been made to integrate the material by alloying it with the base material or by causing a chemical reaction (Japanese Patent Publication No. 47-50893), but manufacturing is complicated and there are problems with productivity. In addition, there are other problems, such as the product's applications are limited and its use at high temperatures is difficult. The present invention solves various problems in these known techniques and is a method for manufacturing a sliding member having self-lubricating properties suitable for use under dry friction conditions in a wide temperature range from room temperature to high temperature. The primary purpose is to obtain. Further, the present invention provides that under dry friction conditions,
A second object of the present invention is to provide a method for manufacturing a sliding member that does not generate frictional noise due to chatter vibration (frictional noise due to stick slip). Furthermore, the present invention can easily reduce the area ratio occupied by the fluororesin thread (which functions as a solid lubricant) on the sliding surface without substantially reducing the mechanical strength of the sliding member, and moreover, can increase the width of the sliding member. The third objective is to obtain a method for manufacturing a sliding member that can be changed to The sliding member according to the present invention includes: (1) A mesh A obtained by weaving or knitting thin metal wires and a mesh B obtained by co-weaving or co-knitting the thin metal wires and fluororesin threads. (2) forming a wound laminate by winding the net A from one end and arranging the net B on the inner peripheral surface or the outermost peripheral surface; and (3) forming the wound laminate with gold. The step of inserting the wound laminate into a mold and compressing it in a direction along the winding axis to substantially close the mesh and forming a compression molded product in which the thin metal wires between the layers are entangled with each other. , Forming at least the surface of the compression molded product, which becomes a sliding surface, into a smooth surface in which thin metal wires and fluororesin threads are exposed in a ratio of 10 to 65% of the metal part and 35 to 90% of the resin part. It is characterized by: DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS. 1 to 6 of the accompanying drawings showing embodiments thereof and manufacturing steps thereof. First, the thin metal wire used in the present invention has a purpose,
The most suitable one is selected depending on the purpose, but in particular,
Stainless steel wires are used as iron-based metal wires, and thin wires made of brass, nickel silver, perillium bronze, phosphor bronze, cupronickel, etc. are used as copper alloy-based metal wires, and aluminum alloy wires are also used. For normal applications, copper alloy wire is used, under high temperature or corrosive atmosphere conditions, stainless steel wire or cupronickel wire is used, and under relatively high-speed sliding conditions, aluminum alloy wire is used. are recommended, respectively. The diameter of the thin wire is about 0.1 to 0.5 mm, which forms a net and is most suitable for application to sliding members. In other words, if the net is too thin, it will not only increase the manufacturing difficulty when making the net, but also weaken the sliding surface of the sliding member.On the other hand, if the net is too thick, it will be difficult to manufacture the net as well. This is not only because the smoothness of the sliding surface is impaired. Next, the fluorine resin thread is a thread made of a tetrafluoroethylene resin thread or a tetrafluoroethylene hexafluoride propylene copolymer, and may be a single thread or a spun thread, but it may be a thin metal wire with the wire diameter described above. In the combination, those in the range of approximately 200 to 1200 denyl are preferred. Furthermore, the following two methods can be considered to combine this thread with a thin metal wire. A Method for making a woven net (see Figure 1) As a vertical wire (warp thread), thin metal wire 1a,
A set of the fluorine resin thread 2a is used, and a set of the thin metal wire 1b and the fluorine resin thread 2b is similarly used as the weft wire (weft thread), but both may be used separately as a vertical line and a horizontal line, respectively. B. Method for making a knitted net (see Figure 2) A pair of thin metal wire 1c and fluororesin thread 2c are knitted into a bag shape (the figure shows a developed view). In addition, in the knitted net, the fluorine resin thread 2c is subjected to tension even if it is fed to the braiding machine under the same conditions as the thin metal wire 1c, and the thin metal wire 1c is
It exists between the meshes of c. In addition, the size of the mesh of the mesh made by such a method is usually about 3 to 6 mm, but here, the "mesh" refers to the fine metal wires 1a, 1b,
It refers to the dimension between 1c. In this case, if the mesh size is too large, the compression ratio will increase during winding, compression, and molding, resulting in disadvantages such as the need to deepen the mold cavity.
If it is too fine, the intertwining of the fine wires after compression and molding will be insufficient, which is likely to cause directional problems in the molded product, which may cause problems such as layer cracking, which is not good. In addition, the combination of the thin metal wires 1a, 1b, 1c and the fluorine resin threads 2a, 2b, 2c is such that one thin metal wire is combined with one fluorine resin thread, or one of the former is combined with the latter. Various combinations are possible, such as using two. Furthermore, it is also possible to use a combination of thin metal wires made of different metals. In addition, the area ratio of the metal part and the fluororesin part appearing on the surface of the sliding member made by compression and molding in this way is the same as that of the sliding member obtained under the molding conditions described below. The area ratio is typically 10-65% for the former and 35-90% for the latter. This area ratio is: (a) Wire diameter of the thin metal wire (b) Number of combined fluorine resin threads with respect to the thin metal wire (c) Denyl number of the fluorine resin thread (d) Cross-sectional shape of the fluorine resin thread (e) Difference between whether the fluorine resin yarn is a single yarn or a spun yarn (f) If it is a spun yarn, it varies depending on the number of filaments and the strength of the twist. For example, even if single yarn and spun yarn have the same denier number, a sliding member obtained using a net made of the latter has a larger area ratio of the fluororesin portion. This causes the yarn to "unravel" during compression and molding.
If the "unraveling" becomes significant, the sliding surface will become fluffy, so care must be taken. Although this fluffed material does not adversely affect the coefficient of friction, it not only affects the wear resistance but also causes problems such as poor appearance (decreased commercial value). Note that this fuzz cannot be avoided when the sliding member according to the present invention is manufactured by room temperature molding. However, when RTFE is used as a fluorine resin thread, if a so-called "hot press" method is adopted in which the mold temperature is raised to the firing temperature of PTFE, that is, 260 to 300 degrees Celsius, these fine fluffs will fuse together. death,
Although the fuzz disappears, there is also the problem of increased molding costs. From this point of view, it is particularly preferable to use single yarn when manufacturing the sliding member according to the present invention. Additionally, in response to a request to change the area ratio of the fluorine resin part, we responded by keeping the wire diameter of the fine metal wire constant and changing the denier number of the fluorine resin thread and the number of combinations. This is the most typical and recommended method. To give an example, one fine stainless steel wire (SUB304) with a wire diameter of 0.28 mm is wound with a mesh made by combining two 400 denier RTFE single yarns and knitted at 3 mm. 2.5t/in the axial direction of the laminate
The area ratio occupied by the RTFE portion on the sliding surface of the sliding member obtained by compression and molding under a pressure of cm ² (compression ratio 75%) was approximately 75%. In addition, the mesh shown in Figure 2 (stainless steel thin wire 1c1
The sliding surface of the sliding member obtained by using a combination of one RTFE thread 2c (other conditions are the same as above) has an area ratio of about 45% occupied by the PTFE part. Ta. In this way, by compression molding the wound laminate in its axial direction, only the fine metal wire or only the fluorine resin thread is not biased on the sliding surface of the sliding member, and both are kept at a constant ratio. You will be able to expose it with Here, the function and effect of the fluororesin thread in the sliding member according to the present invention will be explained. It is well known that fluorine resins (particularly PTFE) have extremely low coefficients of friction and are used as solid lubricants like graphite and molybdenum disulfide. (a) There is no difference between the coefficient of static friction (μ _s ) and the coefficient of kinetic friction (μ _k ). Coefficient μ _k
(in Figure 3, the solid and dashed lines represent RTFE and other plastic materials, respectively). ) is also shown. The characteristics (a) and (b) do not cause "stacks and slips" during friction, so they do not produce any frictional noise. On the other hand, those exhibiting negative resistance often generate frictional vibration sounds (squeaks). The same applies to the case where the difference between the two friction coefficients μ _s and μ _k is large. Therefore, when other friction materials are used, even if they are effective in reducing the coefficient of friction, it is difficult to prevent the occurrence of friction noise due to stick slip. Furthermore, when fluororesin is placed on the sliding surface in the form of fluororesin thread, compared to cases where fluororesin is placed on the sliding surface as a pellet (molded product) or powder coating, Excellent wear resistance. This is thought to be due to the fact that when applied in the form of threads, the fluororesin molecules are oriented, resulting in higher strength and a favorable effect on abrasion resistance. In order to make the sliding member of the present invention using the thus obtained wire mesh and the co-woven or co-knitted mesh with fluororesin yarn, one of the following steps is required. [] When a band-shaped net is wound from one end to form a rolled laminate, and this is compressed and molded to obtain a sliding member (i) A winding shaft (round bar, square bar) is used, and around it, For example, the wound laminate 10 (the fourth
5), put it in a mold, and press it in the axial direction of the wound laminate 10 to compress and mold it, thereby creating a sliding member 2 as shown in FIG.
0 is obtained. In this case, at least one wrap of fluorine resin thread is used only on the sliding surface (for example, the outer peripheral surface or the inner peripheral surface), and fluorine resin thread is used on the other surfaces. Ordinary wire mesh can also be used. This method is suitable for obtaining a sliding member 20 having a cylindrical shape (cylindrical, rectangular, partially spherical, etc.). The longitudinal section of this sliding member 20 is as shown in FIG. 6, where 1d represents a pressed thin wire and 2d represents a pressed fluorine resin thread. An example of molding conditions in this case is as follows. Molding temperature Room temperature Molding pressure 1-3t/cm ² Molding time 1-5 seconds Compression 60-85% (ii) A rolled laminate is made by winding a band-shaped net into a solid state without using a winding shaft. This is then put into a mold and compressed by pressing it in the axial direction of the wound laminate. In this case, similar to (i) above,
Only on the sliding surface (for example, the outer peripheral surface),
It is also possible to use a net lined with fluororesin threads. The molding conditions in this method are also the same as in []-(i). Hereinafter, the present invention will be explained with reference to examples. (i) Fine metal wire (a) SUB304 stainless steel wire with a wire diameter of 0.28 mm (b) NSW S-H nickel silver wire with a wire diameter of 0.29 mm (ii) Fluorine resin thread (a) 200 denyl PTFE single yarn (manufactured by Junkosha, (Product name: "Gore-Tex (registered trademark) Y002T1") (b) 400 denyl PTFE single yarn (same as above, product name: "Gore-Tex (registered trademark) Y004T1") (c) 400 denyl PTFE spun yarn (manufactured by Toray Industries, Inc., product name: "Toyoflon (trademark)") Registered trademark) <Number of filaments: 60
(iii) Combination: 1 to 2 PTFE threads for one fine metal wire (iv) Form of net: Bag-knitted net with 3 mm mesh according to the above combination (v) Sliding member: The above net Each band is crushed in the radial direction with a roller and wound to form a rolled laminate, which is mounted on a mold and rolled and laminated using a press with a pressing force of 2.5t/ ^cm2 . Compression molded in the axial direction of the body. The compression ratio [(height of the wound laminate) - (height of the molded body)/(height of the wound laminate) x 100 = Q%] was constant at 74%. The inner diameter surface of the resulting bush-like sliding member was used as a sliding surface for testing. The table shows the results of testing under the following test conditions. Test conditions Load: 50Kg/ ^cm2 Sliding speed: 2.5m/min Ambient temperature: 250℃ (room temperature for comparison products only) Compatible material: SUS304 Test time: 20 hours In sliding members, the coefficient of friction and amount of wear are generally contradictory. However, as can be seen from the table, the product according to the present invention has a performance that is almost equal to or better than that of the comparative product, and especially when the friction coefficient and the amount of wear are evaluated together, it has a well-balanced performance. It is clear that it shows.

【table】

[Table] In addition, compared to comparative products, it is extremely easy to manufacture, and the exposure of the fluorine resin part (area ratio to the sliding surface) can be easily varied over a wide range. . In the comparative product, increasing the proportion of PTFE makes the base metal part weaker (due to the influence of the cutter during machining, or because the small holes have to be placed close to each other, the metal part becomes weaker). , the wear resistance and load carrying capacity of sliding members are likely to be adversely affected. On the other hand, in the case of the present invention, the effect of weakening of the base metal part due to the amount of the PTFE part is extremely small. Further, the comparative product is extremely difficult to manufacture, and furthermore, compared to the comparative product, the present invention can withstand use up to the upper limit of the heat resistance temperature of the fluororesin used, but the comparative product lacks heat resistance. As mentioned above, the sliding member obtained by the manufacturing method of the present invention is made of a physical combination of thin metal wire and fluorocarbon resin thread, so it cannot be made of a casting made of the same material or a sintered bond. Although the overall mechanical strength is not superior to that of gold coated with fluorine resin, it can be used under normal usage conditions (such as load conditions reaching several hundred kg/cm ² and extremely high dimensions). (Except when precision is required)
maintains sufficient strength. In particular, regarding impact strength, it does not break in normal tests (it has toughness), and there is no fear that the fluorine resin part will fall off under impact. In addition, the sliding member obtained by the manufacturing method of the present invention has substantially air permeability because the mesh is almost completely crushed and the fluororesin threads are filled between the thin metal wires. Not yet. As already mentioned, the sliding member obtained by the manufacturing method of the present invention exhibits self-lubricating properties for applications where it is difficult or preferable to apply lubricants such as oil or grease. Although it is characterized in that it can be used effectively, it does not mean that it cannot be used at room temperature or that lubricants cannot be applied. Furthermore, as mentioned above, the sliding member obtained by the manufacturing method of the present invention does not have air permeability, but if necessary, it may be added with several weight percent of lubricating oil.
It is also possible to impregnate it to a certain extent and apply it as an oil-impregnated sliding member. Furthermore, since it has no air permeability, it can also be applied as a sealing material for contact type packing.

[Brief explanation of the drawing]

Figure 1 is a plan view of a net obtained by weaving wire mesh and fluororesin thread, Figure 2 is a developed view of a similar bag-knitted net, and Figure 3 shows the friction velocity and friction. 4 is a diagram showing the relationship between the coefficients of PTFE and other plastic materials; FIG. 4 is a perspective view showing a wound laminate obtained by winding the mesh shown in FIG. 5 is a perspective view of a sliding member obtained by compressing the wound laminate shown in FIG. 4 in the axial direction, and FIG. 6 is an enlarged view of the sliding member shown in FIG. 5. FIG. 1a, 1b, 1c...Thin metal wire, 2a, 2b,
2c...Resin thread made of normal material.

Claims (1)

[Scope of Claims] 1 (1) A net A obtained by weaving or knitting fine metal wires and a net B obtained by co-weaving or co-knitting fine metal wires and fluororesin threads are prepared. (2) forming a wound laminate by winding the net A from one end and arranging the net B on the inner peripheral surface or the outermost peripheral surface; and (3) molding the wound laminate into a mold. and compressing the wound laminate in a direction along its winding axis to substantially close the mesh and form a compression molded product in which thin metal wires between the layers are intertwined with each other, At least the sliding surface of the compression molded product is formed into a smooth surface where fine metal wires and fluorine resin threads are exposed at a ratio of 10 to 65% of the metal part and 35 to 90% of the resin part. A method of manufacturing a sliding member having a characteristic self-lubricating property. 2. The method of manufacturing a sliding member having self-lubricating properties according to claim 1, wherein the thin metal wire is made of a stainless steel wire, a copper alloy wire, or an aluminum alloy wire. 3 The fluorine resin thread is a tetrafluoroethylene resin thread,
A method for manufacturing a sliding member having self-lubricating properties according to claim 1, wherein the thread is made of a copolymer of tetrafluoroethylene and hexafluoropropylene copolymer.