Preparation process of special high-temperature alloy bar for air valve of internal combustion engine

Abstract

The invention provides a preparation process of a special high-temperature alloy bar for an air valve of an internal combustion engine. The method comprises the steps that S1, raw materials are pretreated and prepared, specifically, after high-purity raw materials are selected, the ratio of all the raw materials is accurately calculated according to the component requirement of a target alloy grade, and after furnace charge is pretreated and subjected to vacuum baking and drying, large raw materials need to be cut into small blocks of 50 mm; the invention provides a preparation process of a special high-temperature alloy bar for an air valve of an internal combustion engine, which comprises the following steps: heating, preserving heat and refining a raw material through a ceramic crucible, conveying high-purity argon to a melt, floating argon bubbles to carry H2, N2 and fine inclusions in the melt to the surface of the melt, and adding a refining agent to prepare the special high-temperature alloy bar for the air valve of the internal combustion engine. The preparation method comprises the following steps: smelting molten slag in a smelting furnace to react with non-metallic inclusions in a melt to generate a low-melting-point slag phase, and increasing the smelting vacuum degree to 10 <-310 >-4 Pa through a vacuum degassing process, so that the vacuum degassing time is prolonged, escape of gases such as H2 and N2 dissolved in the melt is promoted, and the pore defect is reduced.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy bar preparation, and more particularly to a process for preparing special high-temperature alloy bars for internal combustion engine valves. Background Technology

[0002] Special high-temperature alloy bars are a type of rod-shaped profile that can maintain high strength, corrosion resistance, creep resistance, and oxidation resistance in high-temperature environments above 600℃. They are widely used in high-end equipment fields such as aero engines, gas turbines, internal combustion engine valves, and nuclear power equipment.

[0003] In the current process of preparing high-temperature alloy bars, special high-temperature alloys contain a variety of alloying elements such as Cr, Ni, Ti, and Al. Although the purity can be improved by using a dual process of vacuum induction melting (VIM) + electroslag remelting (ESR).

[0004] However, when vacuum melting is used, trace impurities in the raw materials and gases entrained during the melting process may still form tiny pores or brittle inclusions, which can become stress concentration sources. Under the high-frequency opening and closing and the scouring of high-temperature gas, the gas valve will develop cracks from the defects.

[0005] Therefore, it is necessary to provide a process for preparing special high-temperature alloy bars for internal combustion engine valves to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a process for preparing special high-temperature alloy bars for internal combustion engine valves, which solves the problem that trace impurities in raw materials and gases entrained during the smelting process form micropores or brittle inclusions, thereby causing stress concentration sources that reduce product quality.

[0007] To solve the above-mentioned technical problems, the present invention provides a process for preparing special high-temperature alloy bars for internal combustion engine valves, comprising the following steps; S1: Raw material pretreatment and batching: After selecting high-purity raw materials, the proportion of each raw material is accurately calculated according to the composition requirements of the target alloy grade. After pretreatment of the furnace charge, the large raw materials are cut into 50mm pieces after vacuum baking and drying. S2: High-purity duplex melting: The pretreated raw materials are loaded into a ceramic crucible, the furnace door is closed, the vacuum pump is started to draw a vacuum until the vacuum degree is <1Pa, the temperature is raised to 1530~1550℃, and after holding and refining for 35~45min, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced. The argon bubbles float up, carrying H2, N2 and fine inclusions in the melt, and float to the surface of the melt. Adding a refining agent causes it to react with non-metallic inclusions in the melt to form a low-melting-point slag phase, which floats to the surface of the melt and is removed by skimming. By using a vacuum degassing process, the smelting vacuum level is increased to 10.-3 10 -4 Pa, prolonging the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt; S3: Homogenization annealing of ingots: The remelted ingots are placed in a high-temperature annealing furnace, heated to 1195~1215℃ and held at that temperature. After holding, the furnace is cooled to 550~600℃ and then removed from the furnace and air-cooled. S4: Hot forming: The annealed ingot is heated to 1150~1180℃ and then drawn in multiple passes on a hydraulic press or high-speed forging machine to forge the ingot into a square billet. The square billet is heated to 1170~1210℃, held for 2 hours, and then rolled in multiple passes through a roll pass mill to gradually roll it into a bar of the target diameter. Finally, it is pickled in a pickling tank. S5: Toughening heat treatment: Heat the hot-rolled bar to 1045~1190℃, hold for 0.5~8h, then cool rapidly, and heat the solution-treated bar to 720~760℃, hold for 4~32h. S6: Finishing and Quality Inspection: Straightening, surface treatment, and non-destructive testing of the bars; S7: Finished product packaging and warehousing: Qualified bars are treated with rust prevention and then classified and stored according to specifications.

[0008] Preferably, in step 2, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced at a flow rate of 0.5-1.0 L / min for 15-20 min.

[0009] Preferably, the refining agent in step 2 is CaO-Al2O3, which is used to react with non-metallic inclusions in the melt to generate a low-melting-point slag phase.

[0010] Preferably, the non-destructive testing in step 6 includes ultrasonic testing, eddy current testing, and performance testing, used to test the bar stock.

[0011] Preferably, the pickling tank in step 4 includes a tank body, and a cleaning device is provided inside the tank body.

[0012] Preferably, the cleaning device includes a moving device, a moving frame, a mounting frame, a filter screen, a mounting groove, a moving plate, and a shovel. The moving device is fixedly installed on one side of the pool body, the moving frame is fixedly installed at the output end of the moving device, the mounting groove is opened inside the moving frame, the mounting frame is disposed inside the moving frame, the filter screen is fixedly installed inside the mounting frame, one side of the moving plate is fixedly connected to one side of the mounting frame, and the shovel is fixedly connected to one side of the moving plate.

[0013] Preferably, the movable frame has a movable slot inside, and a collection box is slidably connected inside the movable slot.

[0014] Preferably, a support frame is fixedly connected to the top of the mobile frame, and a telescopic component is fixedly installed on the top of the support frame.

[0015] Preferably, the telescopic component is a hydraulic rod, which is fixedly installed on the top of the movable frame.

[0016] Preferably, the mounting bracket is provided with a sliding device inside, the sliding device including a sliding groove and a sliding block, the sliding groove being formed inside the mounting bracket, and the sliding block being slidably connected to the inside of the sliding groove.

[0017] Compared with related technologies, the preparation process of special high-temperature alloy rods for internal combustion engine valves provided by the present invention has the following beneficial effects: This invention provides a process for preparing special high-temperature alloy bars for internal combustion engine valves. After refining the raw material by heating and holding it at a ceramic crucible, high-purity argon gas is introduced into the melt. The argon bubbles rise to the surface, carrying H2, N2, and fine inclusions from the melt. A refining agent is then added, reacting with the non-metallic inclusions in the melt to form a low-melting-point slag phase. Finally, a vacuum degassing process is used to increase the melting vacuum to 10. -3 10 -4 Pa extends the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt, reduces porosity defects, thereby increasing the internal density of the alloy, high-temperature tensile strength, fatigue strength, creep strength, improving product performance, and extending service life. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the first embodiment of a manufacturing process for a special high-temperature alloy bar for an internal combustion engine valve provided by the present invention. Figure 2 This is a schematic diagram of the second embodiment of the manufacturing process of a special high-temperature alloy bar for internal combustion engine valves provided by the present invention. Figure 3 for Figure 2 The diagram shows the structure of the cleaning device. Figure 4 for Figure 3 The enlarged schematic diagram of part A is shown.

[0019] The following are the labels in the diagram: 1. Pool body, 2. Cleaning device, 21. Moving device, 22. Moving frame, 23. Mounting frame, 24. Filter screen, 25. Mounting groove, 26. Moving plate, 27. Shovel plate, 3. Moving groove, 4. Collection box, 5. Support frame, 6. Telescopic component, 7. Sliding device, 71. Sliding groove, 72. Sliding block. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] First Embodiment Please refer to the following: Figure 1 ,in, Figure 1 This is a schematic diagram of the first embodiment of a process for preparing a special high-temperature alloy rod for internal combustion engine valves provided by the present invention. The process for preparing a special high-temperature alloy rod for internal combustion engine valves includes the following steps; S1: Raw material pretreatment and batching: After selecting high-purity raw materials, the proportion of each raw material is accurately calculated according to the composition requirements of the target alloy grade. After pretreatment of the furnace charge, the large raw materials are cut into 50mm pieces after vacuum baking and drying. S2: High-purity duplex smelting: The pretreated raw materials are loaded into a ceramic crucible, the furnace door is closed, the vacuum pump is started to evacuate the vacuum to <1Pa, the temperature is raised to 1530~1550℃, and after holding and refining for 35~45min, gases such as H, N, and O and low-melting-point inclusions in the melt are removed. A permeable brick is inserted into the bottom of the melt, and high-purity argon is introduced. The argon bubbles float up, carrying H2, N2 and fine inclusions in the melt, and float to the surface of the melt. Adding a refining agent causes it to react with non-metallic inclusions in the melt to form a low-melting-point slag phase, which floats to the surface of the melt and is removed by skimming. By using a vacuum degassing process, the smelting vacuum level is increased to 10. -3 10 -4 Pa, prolonging the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt; The VIM electrode rod was used as a consumable electrode and inserted into the slag composed of CaF2-Al2O3. After energizing, the electrode was melted by the resistance heat of the slag. After the metal droplets passed through the slag layer, they solidified into ingots in the water-cooled crystallizer. The melting rate was controlled at 3.0~4.2 kg / min to further remove inclusions and refine the grains. S3: Homogenization annealing of ingots: The remelted ingots are placed into a high-temperature annealing furnace and heated to 1195~1215℃. The heating rate is controlled at 5~8℃ / min to avoid cracking of the ingots due to excessive temperature. After heating, the ingots are held at the temperature to ensure full diffusion of elements. After holding, the furnace is cooled to 550~600℃ and then the ingots are air-cooled. S4: Hot forming: Heat the annealed ingot to 1150~1180℃ and hold for 3.5h to ensure uniform temperature penetration. Then, perform multiple upsetting and drawing on a hydraulic press or high-speed forging machine to forge the ingot into a square billet. Heat the square billet to 1170~1210℃ and hold for 2h. Then, use multiple rolling processes to gradually roll it into bars of the target diameter through a roll pass mill. Finally, pickle it in an pickling tank. S5: Toughening heat treatment: Heat the hot-rolled bar to 1045~1190℃, hold for 0.5~8h, then cool rapidly, and heat the solution-treated bar to 720~760℃, hold for 4~32h. S6: Finishing and Quality Inspection: Straightening, surface treatment, and non-destructive testing of the bars; S7: Finished product packaging and warehousing: Qualified bars are treated with rust prevention and then classified and stored according to specifications.

[0022] By pre-treating the raw materials—removing surface oxide scale, oil, and moisture—and eliminating the gases (H2, O2, N2) adsorbed by the raw materials through vacuum baking or hydrogen reduction.

[0023] Straightening: Pressure straightening or roller straightening is used to control the straightness to 0.1 mm / m to avoid bending from affecting subsequent cutting processes.

[0024] Surface treatment: The oxide scale and scratches on the surface are removed by grinding and polishing, so that the surface roughness Ra is 0.8 μm.

[0025] In step 2, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced at a flow rate of 0.5-1.0 L / min for 15-20 min.

[0026] The refining agent in step 2 is CaO-Al2O3, which is used to react with non-metallic inclusions in the melt to generate a low-melting-point slag phase.

[0027] Refining agents can also be complex refining agents.

[0028] The non-destructive testing in step 6 includes ultrasonic testing, eddy current testing, and performance testing, which are used to test the bar stock.

[0029] Ultrasonic testing: detects internal cracks, porosity and other defects, with a defect equivalent of 1.2 mm.

[0030] Eddy current testing: Detects surface cracks with a crack depth of 0.05 mm.

[0031] Performance testing: Sampling tests are conducted on room temperature tensile strength, high temperature tensile strength (700~800℃), creep strength (700℃ / 1000h), and metallographic structure to ensure that the performance meets the valve usage standards.

[0032] The working principle of the special high-temperature alloy rod preparation process for internal combustion engine valves provided by this invention is as follows: When using it, S1: Raw material pretreatment and batching: After selecting high-purity raw materials, accurately calculate the proportion of each raw material according to the composition requirements of the target alloy grade, and after pretreatment of the furnace charge, after vacuum baking and drying, the large raw materials need to be cut into small pieces of 50mm. S2: High-purity duplex melting: The pretreated raw materials are loaded into a ceramic crucible, the furnace door is closed, the vacuum pump is started to draw a vacuum until the vacuum degree is <1Pa, the temperature is raised to 1530~1550℃, and after holding and refining for 35~45min, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced. The argon bubbles float up, carrying H2, N2 and fine inclusions in the melt, and float to the surface of the melt. Adding a refining agent causes it to react with non-metallic inclusions in the melt to form a low-melting-point slag phase, which floats to the surface of the melt and is removed by skimming. By using a vacuum degassing process, the smelting vacuum level is increased to 10. -3 10 -4 Pa, prolonging the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt; S3: Homogenization annealing of ingots: The remelted ingots are placed in a high-temperature annealing furnace, heated to 1195~1215℃ and held at that temperature. After holding, the furnace is cooled to 550~600℃ and then removed from the furnace and air-cooled. S4: Hot forming: The annealed ingot is heated to 1150~1180℃ and then drawn in multiple passes on a hydraulic press or high-speed forging machine to forge the ingot into a square billet. The square billet is heated to 1170~1210℃, held for 2 hours, and then rolled in multiple passes through a roll pass mill to gradually roll it into a bar of the target diameter. Finally, it is pickled in a pickling tank. S5: Toughening heat treatment: Heat the hot-rolled bar to 1045~1190℃, hold for 0.5~8h, then cool rapidly, and heat the solution-treated bar to 720~760℃, hold for 4~32h. S6: Finishing and Quality Inspection: Straightening, surface treatment, and non-destructive testing of the bars; S7: Finished product packaging and warehousing: Qualified bars are treated with rust prevention and then classified and stored according to specifications.

[0033] Compared with related technologies, the preparation process of special high-temperature alloy rods for internal combustion engine valves provided by the present invention has the following beneficial effects: This invention provides a process for preparing special high-temperature alloy bars for internal combustion engine valves. After refining the raw material by heating and holding it at a ceramic crucible, high-purity argon gas is introduced into the melt. The argon bubbles rise to the surface, carrying H2, N2, and fine inclusions from the melt. A refining agent is then added, reacting with the non-metallic inclusions in the melt to form a low-melting-point slag phase. Finally, a vacuum degassing process is used to increase the melting vacuum to 10. -3 10 -4 Pa extends the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt, reduces porosity defects, thereby increasing the internal density of the alloy, high-temperature tensile strength, fatigue strength, creep strength, improving product performance, and extending service life.

[0034] Second Embodiment Please refer to the following: Figure 2 , Figure 3 and Figure 4 Based on the first embodiment of this application, which provides a process for preparing special high-temperature alloy rods for internal combustion engine valves, the second embodiment of this application proposes another process for preparing such rods. The second embodiment is merely a preferred embodiment of the first embodiment, and its implementation will not affect the independent implementation of the first embodiment.

[0035] Specifically, the difference in the preparation process of a special high-temperature alloy rod for internal combustion engine valves provided in the second embodiment of this application is that it also includes a tank body 1. The pickling tank in step 4 includes a tank body 1, and a cleaning device 2 is provided inside the tank body 1.

[0036] The cleaning device 2 includes a moving device 21, a moving frame 22, a mounting frame 23, a filter screen 24, a mounting groove 25, a moving plate 26, and a scraper plate 27. The moving device 21 is fixedly installed on one side of the pool body 1. The moving frame 22 is fixedly installed at the output end of the moving device 21. The mounting groove 25 is opened inside the moving frame 22. The mounting frame 23 is disposed inside the moving frame 22. The filter screen 24 is fixedly installed inside the mounting frame 23. One side of the moving plate 26 is fixedly connected to one side of the mounting frame 23. The scraper plate 27 is fixedly connected to one side of the moving plate 26.

[0037] The moving device 21 is a linear sliding module, which is used to drive the moving frame 22 to move after startup.

[0038] The scraper 27 is used to scrape off impurities attached to the inner wall of the pool 1.

[0039] The filter screen 24 is used to filter impurities in the liquid inside the pool 1 when it moves from one end to the other inside the pool 1, thereby facilitating the cleaning of impurities inside the pool 1.

[0040] The movable frame 22 has a movable slot 3 inside, and a collection box 4 is slidably connected inside the movable slot 3.

[0041] The collection box 4 is used to collect the impurities scraped off by the shovel 27, making it convenient for subsequent cleaning.

[0042] The top of the movable frame 22 is fixedly connected to a support frame 5, and a telescopic component 6 is fixedly installed on the top of the support frame 5.

[0043] The telescopic component 6 can also be a cylinder or an electric push rod.

[0044] The telescopic component 6 is a hydraulic rod, which is fixedly installed on the top of the movable frame 22.

[0045] The output end of the hydraulic rod is fixedly installed on the top of the mounting bracket 23, and is used to move the mounting bracket 23 after the hydraulic rod is started.

[0046] The mounting bracket 23 is provided with a sliding device 7 inside. The sliding device 7 includes a sliding groove 71 and a sliding block 72. The sliding groove 71 is opened inside the mounting bracket 23, and the sliding block 72 is slidably connected to the inside of the sliding groove 71.

[0047] When it is necessary to clean the impurities filtered on one side of the filter screen 24, the telescopic component 6 is activated to move the mounting bracket 23 inside the mounting groove 25, and at the same time, the two sliding grooves 71 are moved upward on the surfaces of the two sliding blocks 72 respectively. After the mounting bracket 23 moves upward to the appropriate position, the collection box 4 is taken out for cleaning, and one side of the filter screen 24 is cleaned at the same time.

[0048] Two sliding blocks 72 are fixedly connected to the two ends of the inner wall of the mounting groove 25, and two sliding grooves 71 adapted to the sliding blocks 72 are opened inside the mounting frame 23. These grooves are used to limit the mounting frame 23 when it moves upward, thereby increasing the stability of the mounting frame 23 when it moves.

[0049] The working principle of the special high-temperature alloy rod preparation process for internal combustion engine valves provided by this invention is as follows: In use, the moving device 21 is activated to move the moving frame 22 to one side, thereby moving the mounting frame 23 connected to the filter screen 24 inside the pool 1 from one end to the other to filter and block impurities inside the pool 1. At the same time, the scraper plate 27 scrapes off the impurities attached to the inner wall of the pool 1.

[0050] When the mounting bracket 23 is moved to one side to the other end, the impurities in the space between the filter screen 24 and the pool body 1 can be removed.

[0051] Compared with related technologies, the preparation process of special high-temperature alloy rods for internal combustion engine valves provided by the present invention has the following beneficial effects: This invention provides a process for preparing special high-temperature alloy rods for internal combustion engine valves. The cleaning device 2 cleans the impurities inside the pool 1, thus eliminating the need for workers to wear protective clothing and enter the interior of the pool 1 for cleaning, making it convenient to clean the interior of the pool 1.

[0052] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A manufacturing process for special high-temperature alloy bars for internal combustion engine valves, characterized in that, include: The following steps; S1: Raw material pretreatment and batching: After selecting high-purity raw materials, the proportion of each raw material is accurately calculated according to the composition requirements of the target alloy grade. After pretreatment of the furnace charge, the large raw materials are cut into 50mm pieces after vacuum baking and drying. S2: High-purity duplex melting: The pretreated raw materials are loaded into a ceramic crucible, the furnace door is closed, the vacuum pump is started to draw a vacuum until the vacuum degree is <1Pa, the temperature is raised to 1530~1550℃, and after holding and refining for 35~45min, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced. The argon bubbles float up, carrying H2, N2 and fine inclusions in the melt, and float to the surface of the melt. Adding a refining agent causes it to react with non-metallic inclusions in the melt to form a low-melting-point slag phase, which floats to the surface of the melt and is removed by skimming. By using a vacuum degassing process, the smelting vacuum level is increased to 10. -3 10 -4 Pa, prolonging the vacuum degassing time, promotes the escape of dissolved gases such as H2 and N2 from the melt; S3: Homogenization annealing of ingots: The remelted ingots are placed in a high-temperature annealing furnace, heated to 1195~1215℃ and held at that temperature. After holding, the furnace is cooled to 550~600℃ and then removed from the furnace and air-cooled. S4: Hot forming: The annealed ingot is heated to 1150~1180℃ and then drawn in multiple passes on a hydraulic press or high-speed forging machine to forge the ingot into a square billet. The square billet is heated to 1170~1210℃, held for 2 hours, and then rolled in multiple passes through a roll pass mill to gradually roll it into a bar of the target diameter. Finally, it is pickled in a pickling tank. S5: Toughening heat treatment: Heat the hot-rolled bar to 1045~1190℃, hold for 0.5~8h, then cool rapidly, and heat the solution-treated bar to 720~760℃, hold for 4~32h. S6: Finishing and Quality Inspection: Straightening, surface treatment, and non-destructive testing of the bars; S7: Finished product packaging and warehousing: Qualified bars are treated with rust prevention and then classified and stored according to specifications.

2. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 1, characterized in that, In step 2, a permeable brick is inserted into the bottom of the melt, and high-purity argon gas is introduced at a flow rate of 0.5-1.0 L / min for 15-20 min.

3. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 1, characterized in that, The refining agent in step 2 is CaO-Al2O3, which is used to react with non-metallic inclusions in the melt to generate a low-melting-point slag phase.

4. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 1, characterized in that, The non-destructive testing in step 6 includes ultrasonic testing, eddy current testing, and performance testing, which are used to test the bar stock.

5. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 1, characterized in that, The pickling tank in step 4 includes a tank body, and a cleaning device is installed inside the tank body.

6. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 5, characterized in that, The cleaning device includes a mobile device, a mobile frame, a mounting frame, a filter screen, a mounting groove, a mobile plate, and a shovel. The mobile device is fixedly installed on one side of the pool body, the mobile frame is fixedly installed on the output end of the mobile device, the mounting groove is opened inside the mobile frame, the mounting frame is disposed inside the mobile frame, the filter screen is fixedly installed inside the mounting frame, one side of the mobile plate is fixedly connected to one side of the mounting frame, and the shovel is fixedly connected to one side of the mobile plate.

7. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 6, characterized in that, The movable frame has a movable slot inside, and a collection box is slidably connected inside the movable slot.

8. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 7, characterized in that, A support frame is fixedly connected to the top of the mobile frame, and a telescopic component is fixedly installed on the top of the support frame.

9. The manufacturing process of a special high-temperature alloy rod for internal combustion engine valves according to claim 8, characterized in that, The telescopic component is a hydraulic rod, which is fixedly installed on the top of the mobile frame.

10. The manufacturing process of a special high-temperature alloy bar for internal combustion engine valves according to claim 6, characterized in that, The mounting bracket is provided with a sliding device inside. The sliding device includes a sliding groove and a sliding block. The sliding groove is opened inside the mounting bracket, and the sliding block is slidably connected to the inside of the sliding groove.

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