Manufacturing method of sheet material for sliding guideway

Abstract

To provide a sheet material for a slide guide surface that has excellent wear resistance and suppressed distortion.SOLUTION: A sheet material 4 forms a surface to be guided 4a in a guide structure of a machine tool 1. The sheet material 4 is a compressed body of a skive sheet containing a polytetrafluoroethylene resin as the principal component and has a sheet thickness that is thinner than the skive sheet by 1.5-10%. The sheet material 4 is further drawn and has a specific gravity that is larger than the skive sheet by 0.01-0.04.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sheet material for a sliding guideway of a machine tool, which is used in a structure for guiding a work table of the machine tool, etc. Manufacturing method Regarding. [Background technology]

[0002] It is well known that in machine tools, either or both of a guide surface that guides a support table for a workpiece and a guided surface that is guided by the guide surface are slidably guided. For example, in Patent Document 1, a sheet material of a resin composition mainly composed of fluororesin is adhered to the guide surface or the guided surface. This sheet material for the sliding guide surface of the machine tool (hereinafter also referred to as a guide sheet material or a sheet material) is processed into a sheet shape by skiving a compression molded body.

[0003] For example, as guide sheet materials, sheet materials containing polytetrafluoroethylene (PTFE) resin as a main component and copper or copper alloy powder, etc., to ensure the required characteristics (see Patent Document 2), and sheet materials containing 70 to 90 mass % PTFE resin and 10 to 30 mass % of at least one of polyoxybenzoyl and polyphenylene sulfide (see Patent Document 3) are known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-149147 [Patent Document 2] JP 2007-61955 A [Patent Document 3] Japanese Patent Publication No. 127933 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0005] In general, the guide sheet material and the mating sliding surface are lubricated with oil, and the surface of the guide sheet material is scraped to ensure high-precision surface contact with the mating sliding surface. The recesses formed by the scraping process act as oil pockets, which supply lubricating oil between the sliding guide surfaces. However, when cutting powder such as metal is generated during the actual operation of the machine tool and the cutting powder gets mixed in between the sliding guide surfaces, the wear of the resin guide sheet material is accelerated, and the initially expected life of the sheet material may be significantly shortened. Therefore, there is a demand in the market for further improvement in the wear resistance of the guide sheet material.

[0006] In addition, since the conventional guide sheet material is based on PTFE resin, which has extremely low fluidity, and contains copper alloy powder, which has a specific gravity more than twice that of PTFE resin, distortion may occur in the sheet material skived using a billet produced by compression molding and heat treatment. Specifically, when the sheet material is stretched in the skive direction, wave-like undulations (non-flatness) may occur near both sides of the sheet, the sheet may be curved toward one of the side sides in the longitudinal direction on a flat surface (non-straightness), or the sheet may be curved in a U-shape in the width direction (non-flatness). In response to sheet material with such distortion in the shape, a portion without distortion is cut out and used, or a portion with distortion that does not affect the product function is cut out and used. In many cases, the portions near both sides where distortion occurred are removed, which makes it difficult to reduce the price.

[0007] The present invention has been made in view of the above circumstances, and provides a sheet material for a sliding guideway of a machine tool, which has excellent wear resistance and suppresses distortion. Manufacturing method The purpose is to provide. [Means for solving the problem]

[0008] The sheet material for sliding guideways of the present invention is a sheet material for sliding guideways that forms a guide surface or a guided surface in a guide structure of a machine tool, and is characterized in that the sheet material for sliding guideways is a compressed product of a skive sheet whose main component is PTFE resin, and has a sheet thickness that is 1.5 to 10% thinner than that of the skive sheet.

[0009] The sheet material for the sliding guideway is further stretched, and is characterized in that its specific gravity is 0.01 to 0.04 greater than that of the skive sheet.

[0010] The sheet material for sliding guideways is characterized in that it contains powder of a non-ferrous metal having a hardness lower than that of iron.

[0011] The sheet thickness of the above-mentioned sliding guideway sheet material is 0.5 to 2.5 mm.

[0012] In the guide structure of the above-mentioned machine tool, the sheet material for the sliding guideway is adhered to a substrate to form the guide surface or the guided surface, and is characterized in that at least the surface on the side adhered to the substrate is provided with an adhesive treated surface which imparts adhesive strength to the substrate. Effect of the Invention

[0013] The sheet material for sliding guideways of the present invention is a compressed skive sheet mainly composed of PTFE resin, and therefore has excellent low friction characteristics, oil resistance, and coolant resistance. Furthermore, since the sheet thickness is 1.5 to 10% thinner than a skive sheet that has not been compressed (hereinafter, a skive sheet that has not been compressed will simply be called a skive sheet), it is possible to improve wear resistance, correct distortion of the skive sheet, and suppress distortion of the shape.

[0014] The sheet material is further stretched, which further improves the distortion correction effect of the skive sheet. Also, since the specific gravity is 0.01 to 0.04 higher than that of a skive sheet that has not been compressed or stretched, the wear resistance is further improved. Also, since the sheet material contains powder of a non-ferrous metal that is less hard than iron, the PTFE resin guide sheet material can be given wear resistance and compression resistance, and excellent properties as a sheet material can be obtained.

[0015] Since the sheet material has a thickness of 0.5 to 2.5 mm, a shape excellent in linearity, planarity, and flatness can be obtained, and the sheet material has no or little distortion in shape. Note that the sheet thickness most in demand for guide surface sheet materials is in the range of 1.0 to 1.5 mm. Therefore, the guide sheet material according to the present invention, which has improved wear resistance, can be provided even for guide sheet materials with a sheet thickness that is in low demand.

[0016] In the guide structure of a machine tool, a sheet material is adhered to a substrate to form a guide surface or a guided surface, and at least the surface of the sheet material on the side that is adhered to the substrate is formed with an adhesive-enabling treated surface that imparts adhesive strength to the substrate, making it possible to adhere to the substrate with an adhesive. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a guide structure of a machine tool. [Diagram 2] FIG. 2 is a plan view of the sheet material for a sliding guideway of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of a calender machine for compressing a skive sheet. [Figure 4] FIG. 11 is a diagram showing the relationship between the compression ratio and the amount of wear of the sheet materials of the examples and the comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The sheet material for sliding guideways of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of a guide structure of a machine tool. The guide structure of the machine tool 1 includes a guide surface 3a on the upper surface of a saddle 3 that guides a table 2 that is a support base for a workpiece, a guided surface that is guided in sliding contact with this guide surface 3a, and lubricating oil interposed between the guide surface 3a and the guided surface.

[0019] The sheet material for sliding guideway of the present invention is a sliding member that forms a guide surface or a guided surface, and corresponds to sheet material 4 in Fig. 1. In Fig. 1, the lower surface of sheet material 4 forms guided surface 4a. In this guide structure, even when table 2 moves on saddle 3, the table itself does not directly contact guide surface 3a, but guided surface 4a of sheet material 4 provided under table 2 slides against guide surface 3a. Sheet material 4 is adhesively fixed to table 2 via adhesive layer 5.

[0020] A well-known adhesive can be appropriately used as the adhesive used for the adhesive layer 5. For example, an epoxy adhesive, a phenol adhesive, a vinyl ether adhesive, a vinyl acetal adhesive, etc. can be used. Among these, it is preferable to use an epoxy adhesive such as N-5 adhesive (trade name manufactured by NTN Corporation), which has excellent adhesive strength, oil resistance, and coolant resistance.

[0021] FIG. 2 shows a plan view of the sheet material 4. As shown in FIG. 2, the sheet material 4 is a long sheet having a rectangular shape in a plan view. The longitudinal direction (X-axis direction) of the sheet material 4 corresponds to the skive direction in the skive processing, and the width direction of the sheet material 4 corresponds to the Y-axis direction. The longitudinal length of the sheet material 4 is, for example, 5 to 50 m, and is appropriately cut according to the use. The width direction length of the sheet material 4 is, for example, 100 to 1000 mm. In addition, on one or both sides of the sheet material, an adhesive treatment surface is formed on which an adhesive treatment is applied to impart wettability to the PTFE resin and increase the adhesive strength with the substrate. Examples of the adhesive treatment include surface etching treatments such as corona discharge treatment, sputter etching treatment, plasma etching treatment, and ammonia conversion treatment, and ultraviolet irradiation treatment.

[0022] The sheet material for sliding guideways of the present invention uses a skive sheet obtained by skiving a compression molded body mainly composed of PTFE resin as a base material. Skiving is a processing method in which a thin sheet is cut out from the surface of a compression molded body by a lathe, like katsura-maki, and is a processing method widely adopted for processing PTFE resin sheets. Conventional sheet materials for sliding guideways are generally used by subjecting skive-processed skive sheets to an adhesive treatment and cutting them to a predetermined size. However, when the sheet material is stretched in the skive direction, the skive sheet may have shape distortions such as wavy undulations (non-flatness) near both sides of the sheet, curvature toward one of the side sides in the longitudinal direction on a plane (non-straightness), and U-shaped curvature in the width direction (non-flatness), leaving room for improvement.

[0023] In contrast, the sheet material 4 according to the present invention is a compressed body in which both sides of the skive sheet are compressed, and is characterized in that the sheet thickness t of the sheet material 4 is 1.5 to 10% thinner than the sheet thickness T of the skive sheet. This increases the density of the sheet and improves the wear resistance, and also corrects the distortion of the shape of the skive sheet, thereby obtaining a sheet material with suppressed distortion. If the change in sheet thickness is less than 1.5%, there is a risk that the effect of improving the wear resistance cannot be obtained, and if it exceeds 10%, there is a risk that the distortion of the shape may become large. The change in sheet thickness is preferably 2 to 10%. For example, when the sheet thickness T of the skive sheet is 1.55 mm, the sheet thickness t of the sheet material 4 is 1.40 to 1.52 mm. The change in sheet thickness is calculated as a compression rate (%) by the following formula.

[0024] Compression ratio = ((sheet thickness T of skive sheet) - (sheet thickness t of sheet material 4)) / (sheet thickness T of skive sheet) × 100 If the compression ratio exceeds 7%, the effect of improving the abrasion resistance reaches a plateau, so in consideration of cost-effectiveness, the compression ratio is preferably 2 to 7%, and more preferably 4 to 7%.

[0025] The sheet thickness t of the sheet material 4 is preferably 0.50 to 2.50 mm. If the sheet thickness t is less than 0.50 mm, post-processing after bonding the sheet material to a machine tool may be difficult, whereas if the sheet thickness t exceeds 2.50 mm, costs may increase and the time required for correcting distortion may become longer, resulting in reduced productivity.

[0026] The sheet material of the present invention is a compressed body in which both sides of a skive sheet are compressed, and therefore, compared to a skive sheet, the smoothness of both sides is higher and the surface roughness is smaller. The arithmetic mean roughness Ra can be used as an index of surface roughness, and for example, the arithmetic mean roughness Ra of a skive sheet is 2 to 5 μm, whereas the arithmetic mean roughness Ra of the guide sheet material of the present invention is 1 to 3 μm. For example, the Ra of the sheet material of the present invention is about 25% to 50% smaller than the Ra of a skive sheet.

[0027] In addition, by performing the stretching process simultaneously with the compression process, the effect of correcting the non-straightness, non-flatness, and non-planarity of the sheet is enhanced. After the compression and stretching processes, the density of the sheet material increases, so the state of the sheet material changes before and after these processes. The density increases by 0.01 to 0.04 before and after compression on both planes. The compression and stretching processes increase the density of the sheet material and improve its abrasion resistance. Furthermore, the planarity and flatness of the skive sheet are corrected.

[0028] The sheet material 4 is a molded product of a resin composition containing PTFE resin as a main component. PTFE resin has a low friction coefficient and excellent heat resistance, oil resistance, and coolant resistance.

[0029] The resin composition used for the sheet material 4 preferably contains a powder of a non-ferrous metal having a hardness lower than that of iron. The reason for using a powder of a non-ferrous metal having a hardness lower than that of iron is to prevent wear of the mating sliding surface of the sheet material (guide surface 3a of saddle 3 in FIG. 1), which is usually made of an iron-based metal such as a casting. In addition, by containing a powder of a non-ferrous metal having a hardness lower than that of iron, it is possible to impart wear resistance and compression resistance to the sheet material 4.

[0030] The non-ferrous metal powder is preferably contained in an amount of 35 to 60% by mass based on the entire resin composition. If the content of the non-ferrous metal powder is less than 35% by mass, it is difficult to significantly improve the strength (e.g., strength in creep) and wear resistance, and if it exceeds 60% by mass, the low friction characteristics of the PTFE resin may be impaired. Therefore, by setting the content of the non-ferrous metal powder within the above range, it is possible to improve the strength and wear resistance without impairing the low friction characteristics of the PTFE resin, and to prevent creep deformation from occurring and thus prevent a decrease in guiding accuracy. The content of the non-ferrous metal powder is more preferably 40 to 50% by mass.

[0031] As the powder of a non-ferrous metal having low hardness, it is preferable to use a powder of copper or a copper alloy. These powders have advantages such as lower hardness than iron, lower friction coefficient among non-ferrous metals, low cost, and easy processing. Copper alloys are copper alloys made of copper and tin or copper and zinc, so they do not wear out the mating material and can be used as sliding members for machine tools that can withstand high loads.

[0032] When using copper or copper alloy powder, the particle size of the copper or copper alloy powder is preferably 2 to 150 μm. If the particle size exceeds 150 μm, it becomes difficult to uniformly disperse the powder in the PTFE resin due to the large specific gravity of copper or copper alloy, and there is a risk of unevenness or variation in strength and abrasion resistance. Even if the particle size is less than 2 μm, it becomes difficult to uniformly disperse the powder in the PTFE resin. The particle size can be measured, for example, using a particle size distribution measuring device using a laser light scattering method.

[0033] From the above, a resin composition containing copper or a copper alloy as a non-ferrous metal powder in the PTFE resin as the main component is preferable. Furthermore, by making the content of the copper or copper alloy powder 35 to 60 mass %, it is possible to improve the strength and abrasion resistance without impairing the low friction characteristics of the PTFE resin, and it is possible to prevent the deterioration of the guiding accuracy by making creep deformation difficult to occur. In addition, by making the particle size of the copper or copper alloy powder 2 to 150 μm, it is possible to uniformly disperse the powder in the PTFE resin and make the strength and abrasion resistance uniform.

[0034] As described above, the guide sheet material of the present invention is a compressed body in which both planes of a PTFE resin sheet obtained by skiving are compressed. Specifically, the skive sheet is obtained by compressing and stretching the skive sheet. This processing method will be described with reference to FIG. 3. FIG. 3 is a schematic diagram of a calender machine that performs compression processing and the like. The calender machine 11 has an unwinding roller 12 that supplies the skive sheet S, a heating roller 13 that heats and compresses the skive sheet, a water-cooled roller 14, and a winding roller 15 that winds up the sheet material after processing. The skive sheet S is sent from the unwinding roller 12 in the direction of the arrow, passes through the heating roller and the water-cooled roller, and is wound up by the winding roller 15.

[0035] The compression process is performed by a pair of heated rollers 13 (upper roller 13a and lower roller 13b). The skive sheet S passes between the two heated rollers, the upper and lower rollers, and is sandwiched between the rollers to perform the compression process. Both rollers are pressed against each other. The load between the rollers depends on the sheet thickness of the skive sheet, but is, for example, 1 to 10 kN, and preferably 3 to 6 kN. In addition, the surfaces of both rollers are formed smoothly, and it is preferable that the surface roughness is Ra = 0.01 to 0.10 μm.

[0036] The upper and lower two rollers 13a and 13b are preferably heated to a temperature lower than the melting point of the PTFE resin, and more preferably to a temperature higher than the glass transition temperature of the PTFE resin and lower than the melting point. However, since the PTFE resin skive sheet may be discolored by heating, it is necessary to set the temperature at a level at which discoloration does not occur. By heating the upper and lower two rollers to a temperature lower than the melting point of the PTFE resin, it is possible to prevent the sheet material after compression processing from returning to the distorted shape of the raw material, improving flatness and planarity. The temperature of the heating roller 13 is preferably 150 to 250°C, and more preferably 180 to 230°C.

[0037] The stretching process is performed by applying tension to the skive sheet S (unwinding sheet) and the compressed sheet S' (winding sheet) with the boundary between the upper and lower rollers. As in the calender 11 of FIG. 3, the skive sheet S unwound from the unwinding roller 12 is sandwiched between the upper roller 13a and the lower roller 13b and is in close contact with about 1 / 2 of the surface of the upper roller 13a, so that the unwinding tension applied to the unwinding sheet can be controlled by controlling the rotation torque of the unwinding roller 12. In addition, since the skive sheet S is sandwiched between the upper roller 13a and the lower roller 13b and is in close contact with about 1 / 2 of the surface of the lower roller 13b, the winding tension applied to the winding sheet can be controlled by controlling the rotation torque of the winding roller 15. The unwinding tension and the winding tension are, for example, 300 to 1000 N.

[0038] By applying tension to the unwinding sheet, the shape of the skive sheet becomes flat when it passes between the heating rollers, and the flatness and evenness of the sheet S' corrected by compression processing become excellent. By applying tension to the winding sheet, the shape of the compressed sheet S' can be further corrected, and the straightness becomes excellent. In addition, a highly finished sheet material can be obtained without wrinkles.

[0039] The sheet S' that has passed between the heating rollers 13 is cooled by the water-cooled roller 14 and taken up by the take-up roller 15. The taken-up sheet is the sheet material according to the present invention. In this way, the skive sheet is compressed by two smooth-surface heating rollers, one above the other, and is stretched with a predetermined tension, resulting in a sheet material with excellent abrasion resistance and no or little distortion in shape. EXAMPLES

[0040] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0041] A raw material powder (resin composition) containing 55% by mass of PTFE resin and 45% by mass of copper-tin alloy powder was compression molded under predetermined conditions, and sintered to produce a cylindrical compression molded body (billet) made of PTFE resin. This billet was attached to a skive lathe, and skived to obtain a skive sheet having a sheet thickness of 1.55 mm, a width direction length of 330 mm, and a length direction length of 25 m. This skive sheet was compressed and stretched (hereinafter collectively referred to as calendering) using the calendar machine shown in FIG. 3 under the processing conditions shown in Table 1, and the resulting products were obtained as Examples 1 to 3 and 4. Reference example Sheet materials Nos. 1 and 2 were obtained. The obtained sheet materials were evaluated for abrasion resistance and shape change. For the sheet material of Comparative Example 3, a skive sheet, that is, a sheet material that was not subjected to compression processing or stretching processing, was used.

[0042] (1) Abrasion resistance evaluation Calendared sheet material (Examples 1 to 3, Reference example A reciprocating test was carried out using the sheet material (Comparative Example 3) and the unprocessed sheet material (Comparative Example 4), and the wear resistance of each sheet material was evaluated. The conditions of the reciprocating test were a surface pressure of 0.5 MPa, a sliding speed of 10 m / min, and oil lubrication. The wear amount after 25 hours of operation in the reciprocating test was measured. The wear amount was calculated as the average wear depth at three points on the sheet material. The wear amount is shown in Table 1, and the relationship between the wear amount and the compression rate is shown in Figure 4.

[0043] [Table 1]

[0044] From Table 1, it was found that the wear amount of the unprocessed sheet material (Comparative Example 3) was about 10 μm, while the wear amount of the sheet material according to the present invention (Examples 1 to 3) was about 6 to 7 μm, and an improvement in wear resistance of 30 to 40% was observed. Also, from the relationship diagram in Figure 4, it was found that while the effect of improving wear resistance can be obtained if the compression rate is 1.5% or more, the change in wear amount reaches a plateau even if the compression rate is made higher than 7%.

[0045] (2) Shape change evaluation The specific gravity of each sheet material was measured. As a result, the sheet materials according to the present invention (Examples 1 to 3) had a specific gravity 0.01 to 0.04 higher than that of the unprocessed sheet material (Comparative Example 3). Specifically, the sheet material of Example 1 had a specific gravity of 3.39, the sheet material of Example 2 had a specific gravity of 3.40, the sheet material of Example 3 had a specific gravity of 3.42, and the sheet material of Comparative Example 3 had a specific gravity of 3.38.

[0046] For each sheet material, flatness, planarity, and straightness were evaluated in a state where the sheet material was stretched in the longitudinal direction. Flatness indicates the degree of waviness (wavy undulation) caused by the edges in the width direction warping in the height direction at arbitrary intervals in the longitudinal direction, and was evaluated by measuring the height of the waviness with a convex. Flatness indicates the degree of U-shape in the width direction caused by both edges in the width direction curving in the height direction, and was evaluated by measuring the depth of the recess in the approximate center in the width direction with a convex. Straightness indicates the degree to which the overall shape in the longitudinal direction is curved in an approximately fan-like shape, and was evaluated using a tape measure. Specifically, the tape measure was placed against the corners of the leading and trailing ends of one piece of the longitudinal direction of the sheet material, and the gap between the edge in the approximate center in the longitudinal direction and the tape measure was measured. As a result, the sheet material of the present invention (Examples 1 to 3) had flatness of about 1 / 15 to 1 / 20, straightness of about 1 / 20 to 1 / 30, and planarity of about 1 / 15 to 1 / 18 compared to the unprocessed sheet material (Comparative Example 3), and distortion of the shape of the unprocessed sheet material was almost eliminated or significantly reduced.

[0047] In this way, sheet material with a thickness 1.5 to 10% thinner than that of skive sheet through calendaring was found to have productivity of 125 to 140% compared to skive sheet (conventional sheet material for guideways that is not calendared). [Industrial Applicability]

[0048] The sheet material for sliding guideways of the present invention has excellent wear resistance and suppresses distortion, so that the portion to be removed due to distortion can be reduced, productivity can be improved, and the sheet material for sliding guideways of machine tools can be widely used. [Explanation of symbols]

[0049] 1 Machine tools 2 Tables 3. Saddle 4 Sheet material 5 Adhesive layer 11 Calendar machine 12 Unwinding roller 13 Heating roller 14 Water-cooled roller 15 Winding roller S Skive Sheet S' Sheet (sheet material for sliding guideways)

Claims

1. A method for manufacturing a sheet material for a sliding guideway that forms a guide surface or a guided surface in a guide structure of a machine tool, comprising the steps of: The sheet material for the sliding guideway is a compressed and stretched body of a skive sheet made of a resin composition mainly composed of polytetrafluoroethylene resin, The method for producing a sheet material for a sliding guideway of a machine tool comprises obtaining a skive sheet from a compression molded body of the resin composition, and subjecting the skive sheet to compression processing and stretching processing.

2. A method for manufacturing a sheet material for sliding guideways of machine tools as described in claim 1, characterized in that the sheet material for sliding guideways has a sheet thickness 1.5 to 10% thinner than that of the skive sheet.

3. The method for manufacturing a sheet material for a sliding guideway of a machine tool according to claim 1 or 2, characterized in that the sheet material for the sliding guideway has a specific gravity 0.01 to 0.04 greater than that of the skive sheet.

4. 4. The method for manufacturing a sheet material for a sliding guideway of a machine tool according to claim 1, wherein the sheet material for a sliding guideway contains copper or copper alloy powder.

5. The method for manufacturing a sheet material for a sliding guideway of a machine tool according to any one of claims 1 to 4, characterized in that the sheet material for the sliding guideway has a sheet thickness of 0.5 to 2.5 mm.

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