Ultra-long air valve alloy and grinding method and grinding device thereof

Abstract

The invention relates to an ultra-long air valve alloy and a grinding method and device thereof, and belongs to the technical field of air valve alloy manufacturing. The method comprises the steps that a feeding table and a discharging table are placed on the left side and the right side of the centerless grinding machine correspondingly, and supporting devices used for fixing the air valve alloy are arranged on the sides, away from the centerless grinding machine, of the feeding table and the discharging table correspondingly; the air valve alloy sequentially passes through a feeding table, a centerless grinding machine and a discharging table and is fixed through the supporting device; grinding the air valve alloy by using a centerless grinding machine, wherein the grinding process comprises a rough grinding procedure and a fine grinding procedure which are sequentially carried out; the rough grinding procedure comprises a first rough grinding procedure and a second rough grinding procedure which are sequentially carried out; the grinding amount of each time of grinding is controlled to be the same, it is guaranteed that fluctuation generated by air valve alloy in the grinding process is relatively small, and roundness and straightness are guaranteed. And finally, accurate grinding treatment is conducted, and it is guaranteed that the surface quality and roughness of the air valve alloy meet the requirements.

Description

Technical Field

[0001] The invention relates to the technical field of valve alloy manufacturing, and in particular to an ultra-long valve alloy and a grinding method and a grinding device thereof. Background Art

[0002] Valve alloy is a commonly used type of alloy. It is the material with the best high-temperature corrosion resistance and long-term high-temperature performance among valve materials. Therefore, it is used to make exhaust valves for high-end passenger cars and exhaust valves for some commercial vehicles.

[0003] The production process of valve alloys is usually smelting, forging, rolling, heat treatment, peeling, grinding, and the final delivery products are all silver-bright materials with bright surfaces. Since valve alloys need to be processed by electric upsetting or extrusion during valve manufacturing, the surface roughness requirements are relatively high, generally h9-h11 level, to avoid surface cracks during electric upsetting or hot extrusion. Therefore, the last processing step of valve alloys, grinding, is very critical.

[0004] The grinding process has a great influence on the surface quality and dimensional accuracy of the valve alloy. If the grinding process is not properly controlled, the following problems will occur: the out-of-roundness of the parts increases, the parts have edges (polygons), vibration marks on the surface of the parts (i.e., fish spots and straight white lines appear on the surface of the parts), the parts have tapers, the center of the parts is large and the two ends are small, there are circular threads on the surface of the parts, a small piece is cut off the front of the parts, the middle or tail of the parts are cut badly, and the surface brightness of the parts is not bright enough. In addition, due to the rigidity of the valve alloy, the "tail swinging" phenomenon will occur during the grinding process, that is, the silver bright material will have dimensional accuracy out of tolerance and unqualified roundness at the end away from the grinding wheel, which will bring difficulties to the processing of the valve alloy, especially when the valve alloy length exceeds 3 meters, it is more difficult to control. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide an ultra-long valve alloy and a grinding method and a grinding device thereof to ensure that the straightness, out-of-roundness and dimensional tolerance of the valve alloy with a length of more than 3.5 meters meet the requirements.

[0006] In one aspect, the present invention provides a grinding method for an ultra-long valve alloy, the method comprising:

[0007] A feeding table and a discharging table are respectively placed on the left and right sides of the centerless grinder, and a supporting device for fixing the valve alloy is respectively arranged on the side of the feeding table and the discharging table away from the centerless grinder;

[0008] The valve alloy is passed through a feeding table, a centerless grinder and a discharging table in sequence, and is fixed by the supporting device;

[0009] Grinding the valve alloy by a centerless grinder, wherein the grinding process includes a rough grinding process and a fine grinding process performed sequentially; the rough grinding process includes a first rough grinding process and a second rough grinding process performed sequentially;

[0010] Among them, the whole rough grinding process grinds away 80% to 90% of the excess size, each rough grinding process grinds away 40% to 45% respectively, and the fine grinding process grinds away 10% to 20% of the excess size;

[0011] The grinding wheel speed during fine grinding is greater than the grinding wheel speed during rough grinding;

[0012] The gas valve alloy is an austenitic gas valve alloy and has a hardness of HRC25-35.

[0013] Furthermore, the chemical composition of the super-long air valve alloy includes, by mass percentage: C: 0.05-0.15%, Si: 0.20-0.50%, Mn: 0.30-0.80%, P: ≤0.020%, S: ≤0.020%, Cr: 14.00-17.00%, Ni: 30.00-32.00%, Al: 1.30-2.50%, Ti: 2.00-3.00%, Mo: 0.50-2.00%, Nb: 0.50-2.00%, V: 0.20-0.50%, Zr: 0.010-0.040%, and the rest is Fe and unavoidable impurities.

[0014] Furthermore, before the grinding process, a solution treatment is also included, wherein the heating temperature of the solution treatment is 980-1020° C., and the solution treatment is kept at this temperature for 1-5 hours and then water-cooled.

[0015] Furthermore, the rough grinding process uses a resin grinding wheel with a size of Φ300mm / Φ150mm / 120mm and a guide wheel inclination angle of 5°; the rotation speed of the resin grinding wheel is 1200 to 1300 rpm.

[0016] Furthermore, the fine grinding process uses an alumina grinding wheel with a size of Φ310mm / Φ155mm / 130mm and a guide wheel inclination angle of 1°; the rotation speed of the alumina grinding wheel is 1700 to 1900 rpm.

[0017] Furthermore, the length of the super-long air valve alloy is 3.5 to 4.0 meters.

[0018] Furthermore, the straightness of the super-long valve alloy is not greater than 1.00 mm / m, the out-of-roundness is not greater than 12 μm, and the dimensional tolerance is (-0.040 to 0) mm.

[0019] On the other hand, the present invention provides an ultra-long valve alloy obtained by the grinding method of the present invention.

[0020] The present invention also provides an ultra-long valve alloy grinding device for implementing the grinding method of the present invention, wherein the grinding device comprises a centerless grinder, a feed table, a discharge table and a support device;

[0021] A feeding table and a discharging table are respectively placed on the left and right sides of the centerless grinder, and a supporting device for fixing the valve alloy is respectively arranged on the side of the feeding table and the side of the discharging table away from the centerless grinder.

[0022] Further, the supporting device includes a material rack and a clamping device;

[0023] A V-shaped groove is welded on one side of the material rack away from the ground, the length of the V-shaped groove is equal to or less than the length of the material rack, the length direction of the V-shaped groove is consistent with the length direction of the valve alloy, and the valve alloy is placed in the V-shaped groove;

[0024] The clamping device consists of a connecting portion, an abutting portion and two clamping portions, and the valve alloy is clamped in the V-shaped groove by the clamping device.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] 1. The grinding method provided by the present invention divides the original grinding into three processes, including two rough grinding stages and one fine grinding stage. In the rough grinding stage, the excess size is removed as much as possible, and the grinding amount is controlled to be 80% to 90% of the total amount, so as to reduce the processing amount for the subsequent fine grinding, thereby ensuring that the fluctuation of the valve alloy during the grinding process is relatively small, and the roundness and straightness are guaranteed;

[0027] 2. For the super-long valve alloy, when the length exceeds 3 meters, the "tail swinging" phenomenon is easy to occur during the grinding process. Based on this, the present invention designs a grinding processing device, which includes a supporting device for fixing the super-long valve alloy. The supporting device reduces the vibration of the valve alloy, and can prevent the "tail swinging" problem of the super-long valve alloy during the grinding process, thereby ensuring that the fluctuation of the valve alloy during the grinding process is relatively small, and ensuring the roundness and straightness;

[0028] 3. The valve alloy of the present invention is an austenitic valve alloy, which has the characteristics of "soft but hard", and is prone to poor dimensional accuracy, unqualified roundness and the like. The hardness of the valve alloy can be controlled to HRC25-35 after solid solution to ensure the final dimensional requirements of the valve alloy;

[0029] 4. In the present invention, the grinding wheel in the rough grinding stage is a resin grinding wheel, and the grinding wheel in the fine grinding stage is an alumina grinding wheel, and their respective rotation speeds are controlled, and the grinding wheel speed in the fine grinding process is required to be greater than the grinding wheel speed in the rough grinding process. On the one hand, it will not cause clogging of the grinding wheel, protect the valve alloy from being burned, and extend the life of the grinding wheel. On the other hand, it ensures that the surface quality and roughness of the valve alloy meet the requirements.

[0030] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0032] Figure 1 This is a schematic diagram of the placement of the support device on the centerless grinder;

[0033] Figure 2 It is a schematic diagram of the supporting device structure;

[0034] Figure 3 It is a schematic diagram of the structure of the clamping device;

[0035] Reference numerals:

[0036] 1. Centerless grinder; 2. Feeding table; 3. Discharging table; 4. Support device; 41. Material rack; 42. V-shaped groove; 43. Rubber gasket; 44. Clamping device; 441. Clamping part; 442. Connecting part; 443. Abutting part; 5. Valve alloy. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] Valve alloy is one of the materials with the best high-temperature corrosion resistance and long-term high-temperature performance among valve materials, and is also widely used. The preparation process of valve alloy mainly includes smelting, forging, rolling, heat treatment, peeling, grinding and other steps, and the final delivery products are all silver-bright materials with bright surfaces. When valve alloy is used to prepare valves, it is also necessary to perform electric upsetting or extrusion treatment, so the surface roughness requirements are relatively high to avoid surface cracks during electric upsetting or hot extrusion. Therefore, the last processing step of valve alloy, grinding, is very critical.

[0039] The grinding process has a great influence on the surface quality and dimensional accuracy of the valve alloy. If the grinding process is not properly controlled, the following problems will occur: for example, the out-of-roundness of the parts increases and the parts have angular shapes. In addition, due to the rigidity of the valve alloy, the "tail swing" phenomenon will occur during the grinding process, that is, the dimensional accuracy of the silver bright material far away from the grinding wheel will exceed the tolerance, the roundness will be unqualified, etc., which will bring difficulties to the processing of the valve alloy, especially when the length of the valve alloy exceeds 3 meters, it is more difficult to control.

[0040] Therefore, the present invention provides a grinding method for an ultra-long valve alloy, the method comprising:

[0041] A feeding table 2 and a discharging table 3 are respectively placed on the left and right sides of the centerless grinder 1, and a supporting device 4 for fixing a valve alloy 5 is respectively arranged on the side of the feeding table 2 and the discharging table 3 away from the centerless grinder 1;

[0042] The valve alloy 5 is passed through the feed table 2, the centerless grinder 1 and the discharge table 3 in sequence, and is fixed by the support device 4;

[0043] Grinding the valve alloy 5 by using a centerless grinder 1, wherein the grinding process includes a rough grinding process and a fine grinding process performed sequentially; the rough grinding process includes a first rough grinding process and a second rough grinding process performed sequentially;

[0044] Among them, the whole rough grinding process grinds away 80% to 90% of the excess size, each rough grinding process grinds away 40% to 45% respectively, and the fine grinding process grinds away 10% to 20% of the excess size;

[0045] The grinding wheel speed during fine grinding is greater than the grinding wheel speed during rough grinding;

[0046] The gas valve alloy is an austenitic gas valve alloy and has a hardness of HRC25-35.

[0047] Compared with the prior art, the grinding method provided by the present invention is to respectively set a support device 4 for fixing the valve alloy 5 on the side of the feed table 2 and the discharge table 3 away from the centerless grinder 1, and cooperate with the grinding process of the present invention, and then divide the original one-time grinding into three processes, including two rough grinding stages and one fine grinding stage. In the rough grinding stage, the excess size is removed as much as possible, and the grinding amount is controlled to be 80% to 90% of the total amount, so as to reduce the processing amount for subsequent fine grinding. In addition, the rough grinding process is divided into more than two grindings, and the grinding amount of each grinding is controlled to be the same, which can prevent the "tail swinging" problem of the super-long valve alloy during the grinding process, thereby ensuring that the fluctuation of the valve alloy during the grinding process is relatively small, and the roundness and straightness are guaranteed. Finally, fine grinding is performed to ensure that the surface quality and roughness of the valve alloy meet the requirements.

[0048] The choice of grinding process directly affects the surface quality and dimensional accuracy of the valve alloy. During the grinding process, due to the friction between the grinding wheel and the valve alloy, the temperature of the grinding area is very high, and the grinding chips are continuously oxidized and melted, clinging to the abrasive on the grinding wheel. If the grinding process is not selected properly, it will cause the grinding wheel to be blocked, resulting in a decrease in grinding accuracy, and even burn the valve alloy, shortening the life of the grinding wheel.

[0049] Specifically, the rough grinding process uses a resin grinding wheel with a size of Φ300mm / Φ150mm / 120mm and a guide wheel inclination angle of 5°.

[0050] It should be noted that in the rough grinding stage of the present invention, the grinding wheel used is a resin grinding wheel with an outer diameter of Φ300 mm, an inner diameter of Φ150 mm, and a thickness of 120 mm. The resin grinding wheel has high strength and certain elasticity, which is beneficial to improving the roughness of the valve alloy surface, reducing heat generation and clogging during grinding, and improving grinding accuracy.

[0051] Specifically, the fine grinding process uses an alumina grinding wheel with a size of Φ310mm / Φ155mm / 130mm and a guide wheel inclination angle of 1°.

[0052] It should be noted that in the fine grinding stage of the present invention, an alumina grinding wheel is used, with an outer diameter of Φ310mm, an inner diameter of Φ155mm, and a thickness of 130mm. It has the characteristics of high hardness, good strength, good wear resistance, and good heat dissipation, which ensure the efficiency of fine grinding on the one hand, and the surface quality of the valve alloy after fine grinding on the other hand. The alumina grinding wheel can provide a stable grinding force during the grinding process, reduce the impact of grinding force fluctuations on the surface of the valve alloy, and thus obtain a smoother and more precise surface. In addition, the high hardness and good heat dissipation performance of the alumina grinding wheel help to reduce the generation of grinding heat, avoid thermal damage to the valve alloy during the grinding process, and ensure the stability and reliability of the grinding process.

[0053] Specifically, the rotation speed of the resin grinding wheel is 1200 to 1300 rpm.

[0054] Specifically, the rotation speed of the alumina grinding wheel is 1700-1900 rpm.

[0055] During the rough grinding stage, if the grinding wheel speed is lower than 1200 rpm, the grinding efficiency will drop significantly, because the lower speed means that the number of times the grinding wheel contacts the workpiece per unit time is reduced, thereby reducing the material removal rate. At the same time, due to insufficient grinding force, the excess material on the surface of the valve alloy may not be effectively removed, resulting in increased surface roughness and affecting the quality of subsequent processing. On the other hand, if the grinding wheel speed is higher than 1300 rpm, although the grinding efficiency will be improved, the excessively high speed will increase the generation of grinding heat, which may cause burns or thermal cracks on the surface of the valve alloy, affecting the mechanical properties and surface integrity of the material.

[0056] In the fine grinding stage, the control of rotation speed is also crucial. When the grinding wheel speed is lower than 1700 rpm, the grinding force may not be sufficient to achieve the ideal fine grinding effect, resulting in the valve alloy surface not being able to obtain sufficient smoothness, affecting the final quality of the product. When the grinding wheel speed exceeds 1900 rpm, although it can improve the grinding efficiency, the excessively high speed will also increase the grinding heat, which may cause thermal damage to the valve alloy surface, and even affect the internal structure of the material, reducing the service life of the product. Therefore, reasonable control of the grinding wheel speed is crucial to ensure the quality and efficiency of the grinding process, especially the speed in the fine grinding stage should be higher than that in the rough grinding stage.

[0057] Specifically, the chemical composition of the super-long air valve alloy includes, by mass percentage: C: 0.05-0.15%, Si: 0.20-0.50%, Mn: 0.30-0.80%, P: ≤0.020%, S: ≤0.020%, Cr: 14.00-17.00%, Ni: 30.00-32.00%, Al: 1.30-2.50%, Ti: 2.00-3.00%, Mo: 0.50-2.00%, Nb: 0.50-2.00%, V: 0.20-0.50%, Zr: 0.010-0.040%, and the rest is Fe and unavoidable impurities.

[0058] It should be noted that the present invention provides an austenitic valve alloy, which is mainly divided into martensitic valve alloy and austenitic valve alloy, and the martensitic valve alloy is harder and is not prone to problems during the grinding process. However, the austenitic valve alloy exhibits a certain "stickiness", that is, it is hard in the soft, and is very prone to poor dimensional accuracy, unqualified roundness, etc.

[0059] Specifically, before the grinding process, a solution treatment is also included, and the solution treatment is water cooling at 980-1020° C.×1-5h.

[0060] It should be noted that in the present invention, the valve alloy needs to be solution treated before the grinding process to adjust the hardness of the valve alloy to HRC25-HRC35. When the solution treatment is insufficient, the hardness of the valve alloy is too high, the grinding process is more time-consuming, and the risk of poor dimensional accuracy, unqualified roundness, etc. is increased. If the solution temperature is too high or the time is too long, the valve alloy is overall soft, and the risk of deformation of the valve alloy is increased during the grinding process.

[0061] Specifically, the straightness of the super-long valve alloy is no more than 1.00 mm / m, the out-of-roundness is no more than 12 μm, and the dimensional tolerance is (-0.040 to 0) mm.

[0062] The invention provides an ultra-long gas valve alloy, which is formed into a disc after smelting, forging, rolling and solid solution treatment, and the disc enters a grinding process after straightening. The length of the ultra-long gas valve alloy is 3.5-4.0 meters.

[0063] It should be noted that the valve alloy can be smelted by vacuum induction + electroslag remelting, non-vacuum induction + electroslag remelting, vacuum induction + vacuum consumable, electric furnace + external refining + electroslag remelting, etc. The electroslag remelting process is carried out in a gas-protected atmosphere furnace. After annealing, the smelted alloy ingot is cut off from the head and tail, and then forged, rolled and solution treated.

[0064] In the present invention, a centerless grinder 1 is mainly used to grind the valve alloy 5. A feed table 2 is placed on one side of the centerless grinder 1, and a discharge table 3 is placed on one side of the centerless grinder 1. As the length of the valve alloy 5 gradually increases, especially when the length exceeds 3 meters, the valve alloy 5 gradually starts to shake, that is, a "tail swing" phenomenon occurs, and the dimensional accuracy of the ultra-long valve alloy cannot be guaranteed.

[0065] In order to prevent the "tail swinging" phenomenon from occurring during the grinding process and ensure that the straightness, out-of-roundness and dimensional tolerance of the extra-long valve alloy 5 meet the requirements, the measures taken by the present invention are to install a supporting device 4 on the outside of the feed table 2 and the discharge table 3 of the centerless grinder 1, respectively, to place or fix the unpolished and polished parts, respectively.

[0066] Specifically, the supporting device 4 includes a material rack 41 , a V-shaped groove 42 and a clamping device 44 .

[0067] It should be noted that, at the beginning stage of grinding, one end of the valve alloy 5 enters the centerless grinder 1 from one end of the feed table 2 driven by the guide wheel. At this time, in order to avoid a large processing error of the part being ground due to excessive length and insufficient rigidity during the rotation of the valve alloy 5, a clamping device 44 is arranged in the support device 4 on the outside of the feed table 2. The clamping device 44 can apply an appropriate clamping force so that the part can move forward smoothly in the V-groove 42 without jumping, thereby ensuring that the part being ground can be processed within a smaller error range.

[0068] When the valve alloy 5 is processed to the end, most of the valve alloy 5 has entered the discharge table 3. At this time, the rotation of the processed part during the processing will still cause the size of the processed part to exceed the tolerance. At this time, applying appropriate clamping force to the processed part of the valve alloy 5 reduces the vibration of the valve alloy 5, which can effectively prevent the "tail swing" phenomenon and cause dimensional disqualification. Therefore, this support device 4 on both sides of the feed table 2 and the discharge table 3 can ensure that the processed parts can be within the effective tolerance, thereby achieving the purpose of processing super-long parts.

[0069] Preferably, the material rack 41 is a rectangular parallelepiped, placed on the ground, and placed on the side of the feed table 2 and the discharge table 3 away from the centerless grinder 1. A V-shaped groove 42 is welded on the side of the material rack 41 away from the ground, and the length of the V-shaped groove 42 is equal to or less than the length of the material rack 41, and the length direction of the V-shaped groove 42 is consistent with the length direction of the valve alloy 5. The clamping device 44 is located above the V-shaped groove 42, and the clamping device 44 is used to clamp the V-shaped groove 42 and the valve alloy 5.

[0070] Preferably, the clamping device 44 is composed of two clamping parts 441, a connecting part 442 and an abutting part 443, the two clamping parts 441 are respectively fixed at the two ends of the connecting part 442, and the angle between the clamping parts 441 is equal to the angle of the V-groove, the abutting part 443 is fixed on the connecting part 442, and the abutting part 443 is located on the side of the connecting part 442 close to the valve alloy 5.

[0071] During use, the valve alloy 5 is placed in the V-shaped groove 42, and the clamping device 44 is clamped on the outside of the V-shaped groove 42. Specifically, the two clamping parts 441 are respectively located on the outside of the V-shaped groove 42 and fit therewith, and the connecting part 442 is located above the V-shaped groove 42 to connect and fix the two clamping parts 441; the abutting part 443 is located on the connecting part 442 and abuts against the valve alloy 5, and the length of the abutting part 443 is greater than the diameter of the valve alloy 5.

[0072] The valve alloy 5 is placed in the V-shaped groove 42, and the outer peripheral surface of the valve alloy 5 abuts against the inner wall of the V-shaped groove 42. Due to the effect of gravity, the valve alloy 5 squeezes the V-shaped groove 42, so that the two sides of the V-shaped groove 42 move toward each other. Since a clamping device 44 is placed on the V-shaped groove 42, the clamping device 44 prevents the two sides of the V-shaped groove 42 from moving toward each other, and the abutting portion 443 in the clamping device 44 abuts against the valve alloy 5. Therefore, the valve alloy 5 is fixed in the V-shaped groove 42 and cannot jump, but can rotate around its own axis.

[0073] Preferably, the clamping portion 441 , the connecting portion 442 and the abutting portion 443 are integrally formed.

[0074] Preferably, the included angle between the two side surfaces of the V-shaped groove 42 is 60°.

[0075] Preferably, a rubber gasket 43 is placed between the V-shaped groove 42 and the valve alloy 5 .

[0076] Preferably, the center of the V-shaped groove 42 is in a straight line with the axis of the feeding mechanism.

[0077] It should be noted that the material rack 41 is the main frame of the support device 4, which is welded from low carbon steel and plays the role of supporting and fixing the V-groove 42. The length of the material rack 41 can be determined according to the length of the valve alloy 5 to be processed. The V-groove 42 is welded from low carbon steel, and the angle between the two sides of the V-groove 42 is 60°. A rubber pad 43 is fixed on the surface of the V-groove 42, and the center of the V-groove 42 is in a straight line with the axis of the feeding mechanism. The clamping device 44 is located above the V-groove 42. After applying the clamping force, the valve alloy in the V-groove 42 can be compressed to prevent it from jumping during the grinding process. The biggest difficulty in using the centerless grinder 1 to process super-long valve alloys is that due to the insufficient rigidity of the super-long valve alloys, the part away from the grinding wheel "swings" during the grinding process, resulting in the surface quality and dimensional accuracy of the valve alloy failing to meet the requirements.

[0078] In order to better meet the use of the valve alloy 5 under different diameters and better fix the valve alloy 5 in the V-shaped groove 42, rubber gaskets 43 of different thicknesses can be placed between the valve alloy 5 and the abutment 443 or the size of the abutment 443 can be changed.

[0079] In the present invention, the preparation process of the valve alloy includes smelting, blanking forging, rolling, solution treatment and grinding. The diameters of the wire rods formed after rolling are Φ12.0mm, Φ10.5mm, Φ9.5mm and Φ9.0mm, and the diameters of the final products are Φ11.5mm, Φ10.0mm, Φ9.0mm and Φ8.5mm respectively. The valve alloy enters the grinding process after solution treatment and straightening. In order to more clearly describe the present invention, the following examples and comparative examples are further explained.

[0080] Examples 1-6

[0081] The chemical composition of the valve alloys of Examples 1-6 of the present invention is shown in Table 1, and the hardness and specifications of the solution treatment process are shown in Table 2.

[0082] Table 1 Chemical composition of valve alloys of Examples 1-6

[0083]

[0084]

[0085] Table 2 Solution treatment process hardness and specifications

[0086]

[0087] * The ingredients of Comparative Examples 1 and 2 are the same as those of Example 1.

[0088] During the grinding phase: refer to Figure 1 and Figure 2 .

[0089] A support device 4 is installed on each side of the feed port and the discharge port of the centerless grinder 1. The support device 4 is composed of a material rack 41, a V-shaped groove 42, a rubber pad 43 in the V-shaped groove 42, and a clamping device 44. The material rack 41 is the main frame of the support device 4, which is welded from low carbon steel and serves to place the V-shaped groove 42. The length of the material rack 41 is 1.0 meter. The V-shaped groove 42 is welded from low carbon steel, and the angle between the two sides of the V-shaped groove 42 is 60°. A rubber pad 43 is fixed on the surface of the V-shaped groove 42, and the center of the V-shaped groove 42 is in a straight line with the axis of the feed and discharge mechanism.

[0090] The clamping device 44 is composed of two clamping parts 441, a connecting part 442 and an abutting part 443. The clamping parts 441, the connecting part 442 and the abutting part 443 are integrally formed; the clamping parts 441 are respectively located on the outside of the V-shaped groove 42 and fit therewith, the connecting part 442 is located above the V-shaped groove 42, connecting and fixing the two clamping parts 441; the abutting part 443 is located on the connecting part 442 and abuts against the valve alloy 5. The valve alloy 5 in the V-shaped groove 42 can be compressed by applying a clamping force through the clamping device 44 to prevent it from jumping during the grinding process. A group of clamping devices 44 are placed every 30 cm above the V-shaped groove 42, and a total of 4 groups are placed.

[0091] The whole grinding process is divided into three steps, the first two are rough grinding steps, and the last one is fine grinding step. The grinding process adopts centerless grinder 1. The whole rough grinding process grinds off 80% to 90% of the excess size, each rough grinding process grinds off 40% to 45%, and the fine grinding process grinds off 10% to 20% of the excess size. The rough grinding process adopts resin grinding wheel with size of Φ300mm / Φ150mm / 120mm, speed of 1200 to 1300 rpm, and guide wheel inclination of 5°.

[0092] The fine grinding process uses an alumina grinding wheel with a size of Φ310mm / Φ155mm / 130mm and a rotation speed of 1700 to 1900 rpm. The grinding speeds of the rough grinding process and the fine grinding process of different specifications of valve alloy 5 are shown in Table 3.

[0093] Table 3 Grinding process

[0094]

[0095] Comparative Example 1

[0096] The preparation process of Comparative Example 1 is substantially the same as that of Example 1, except that Comparative Example 1 only includes coarse grinding and fine grinding. In the coarse grinding stage, 65% of the excess size is ground off; in the fine grinding stage, 35% of the excess size is ground off.

[0097] Comparative Example 2

[0098] The preparation process of Comparative Example 2 is substantially the same as that of Example 1, except that the rotation speed of the grinding wheel in the rough grinding stage and the fine grinding stage in Comparative Example 2 is both 1400 rpm.

[0099] Comparative Example 3

[0100] The preparation process of Comparative Example 3 is substantially the same as that of Example 1, except that no supporting device is used in Comparative Example 3.

[0101] Performance Testing

[0102] The above-mentioned embodiments 1-6 and comparative examples 1-3 were subjected to dimensional inspection, mainly including straightness, out-of-roundness and dimensional tolerance. The inspection results are shown in Table 4.

[0103] Table 4 Performance test results

[0104] Group Straightness(mm / m) Out of roundness(μm) Dimensional tolerance (mm) Example 1 0.87 10.2 -0.036 Example 2 0.91 11.3 -0.033 Example 3 0.88 9.8 -0.029 Example 4 0.92 10.1 -0.035 Example 5 0.75 10.0 -0.030 Example 6 0.82 9.9 -0.031 Comparative Example 1 1.25 13.2 -0.044 Comparative Example 2 1.33 12.8 -0.038 Comparative Example 3 1.41 13.5 -0.041

[0105] It can be seen from the combination of Examples 1-6 and Comparative Examples 1-3 and referring to Table 4 that the grinding process provided by Examples 1-6 of the present invention can ensure that the fluctuations in the grinding process of the austenitic valve alloy are relatively small, and the roundness and straightness are guaranteed, with the straightness below 1.00 mm / m and the out-of-roundness below 11.3 μm, and finally a valve alloy with a length of more than 3.5 m can be prepared.

[0106] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A grinding method for an ultra-long valve alloy, characterized in that: The method comprises: A feeding table and a discharging table are respectively placed on the left and right sides of the centerless grinder, and a supporting device for fixing the valve alloy is respectively arranged on the side of the feeding table and the discharging table away from the centerless grinder; The valve alloy is passed through a feeding table, a centerless grinder and a discharging table in sequence, and is fixed by the supporting device; Grinding the valve alloy by a centerless grinder, wherein the grinding process includes a rough grinding process and a fine grinding process performed sequentially; the rough grinding process includes a first rough grinding process and a second rough grinding process performed sequentially; Among them, the whole rough grinding process grinds away 80% to 90% of the excess size, each rough grinding process grinds away 40% to 45% respectively, and the fine grinding process grinds away 10% to 20% of the excess size; The grinding wheel speed during fine grinding is greater than the grinding wheel speed during rough grinding; The gas valve alloy is an austenitic gas valve alloy and has a hardness of HRC25-35.

2. The grinding method of the super-long valve alloy according to claim 1, characterized in that: The chemical composition of the super-long air valve alloy includes, by mass percentage, C: 0.05-0.15%, Si: 0.20-0.50%, Mn: 0.30-0.80%, P: ≤0.020%, S: ≤0.020%, Cr: 14.00-17.00%, Ni: 30.00-32.00%, Al: 1.30-2.50%, Ti: 2.00-3.00%, Mo: 0.50-2.00%, Nb: 0.50-2.00%, V: 0.20-0.50%, Zr: 0.010-0.040%, and the rest is Fe and unavoidable impurities.

3. The grinding method of the super-long valve alloy according to claim 1, characterized in that: Before the grinding process, a solution treatment is also included. The heating temperature of the solution treatment is 980-1020° C., and the temperature is kept for 1-5 hours before water cooling.

4. The grinding method of the super-long valve alloy according to claim 1, characterized in that: The rough grinding process uses a resin grinding wheel with a size of Φ300mm / Φ150mm / 120mm and a guide wheel inclination angle of 5°; the rotation speed of the resin grinding wheel is 1200 to 1300 rpm.

5. The grinding method of the super-long valve alloy according to claim 1, characterized in that: The fine grinding process uses an aluminum oxide grinding wheel with a size of Φ310mm / Φ155mm / 130mm and a guide wheel inclination angle of 1°; the rotation speed of the aluminum oxide grinding wheel is 1700 to 1900 rpm.

6. The grinding method of the super-long valve alloy according to claim 1, characterized in that: The length of the super-long air valve alloy is 3.5 to 4.0 meters.

7. The grinding method of the super-long valve alloy according to claim 1, characterized in that: The straightness of the super-long valve alloy is no more than 1.00 mm / m, the out-of-roundness is no more than 12 μm, and the dimensional tolerance is (-0.040 to 0) mm.

8. An ultra-long valve alloy, characterized in that: Obtained by the grinding method according to any one of claims 1-7.

9. An ultra-long valve alloy grinding device, characterized in that: Used to implement the grinding method according to any one of claims 1 to 7, the grinding device comprises a centerless grinder, a feed table, a discharge table and a support device; A feeding table and a discharging table are respectively placed on the left and right sides of the centerless grinder, and a supporting device for fixing the valve alloy is respectively arranged on the side of the feeding table and the side of the discharging table away from the centerless grinder.

10. The super-long valve alloy grinding processing device according to claim 9, characterized in that: The supporting device comprises a material rack and a clamping device; A V-shaped groove is welded on one side of the material rack away from the ground, the length of the V-shaped groove is equal to or less than the length of the material rack, the length direction of the V-shaped groove is consistent with the length direction of the valve alloy, and the valve alloy is placed in the V-shaped groove; The clamping device consists of a connecting portion, an abutting portion and two clamping portions, and the valve alloy is clamped in the V-shaped groove by the clamping device.

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