A pre-hardened die steel alloy and method of making the same

Abstract

The present application relates to a kind of pre-hardened die steel alloy and its preparation method, alloy chemical composition and its mass percentage are as follows: carbon 0.40~0.50%, silicon 0.20~0.40%, manganese 1.20~1.60%, sulfur ≤0.010%, phosphorus ≤0.025%, chromium 1.50~1.80%, molybdenum 0.35~0.50%, vanadium 0.15~0.25%, nickel 1.65~1.85%, copper ≤0.20%, iron is the balance, and residual gas content is nitrogen ≤70ppm, hydrogen ≤1.0ppm, oxygen ≤20ppm;The pre-hardened die steel alloy of the present application is directly pre-hardened to 44‑46HRC, with good processing performance simultaneously, can be directly cut into die finished product, without secondary quenching, save the cost of vacuum heat treatment and heat treatment time, can replace die steel 1.2343, with great performance advantage and competitive advantage.

Description

Technical Field

[0001] This invention relates to the field of metal alloy technology, and in particular to a pre-hardened mold steel alloy and its preparation method. Background Technology

[0002] Die steel 1.2343 is a steel grade currently available on the market. It is a European standard grade, corresponding to the American standard grade H11, and the Chinese grade 4Cr5MoVSi. Its main alloy composition is: carbon (C) 0.36~0.42%, chromium (Cr) 4.80~5.20%, molybdenum (Mo) 1.10~1.40%, vanadium (V) 0.30~0.50%, silicon (Si) 0.80~1.20%, manganese (Mn) 0.30~0.50%, phosphorus (P) ≤0.015%, and sulfur (S) ≤0.002%.

[0003] After smelting, forging, and annealing, mold steel 1.2343 has a hardness of less than 230 HB, which is relatively low, resulting in relatively good machinability. However, it requires secondary hardening through vacuum heat treatment, i.e., quenching and tempering, to achieve the designed hardness (44-46 HRC). Therefore, mold steel 1.2343 can only be annealed and delivered to the mold factory, where it is then rough-machined into a mold blank, followed by vacuum quenching and tempering, and finally finish-machined into the finished mold. If mold steel 1.2343 is directly pre-hardened and tempered to 44-46 HRC for heavy cutting, the tool pressure will create a work-hardened layer and residual tensile stress on the mold surface, severely reducing the mold's resistance to thermal fatigue and cracking. This leads to long mold manufacturing cycles and high production costs.

[0004] Therefore, this invention proposes a pre-hardened mold steel alloy and its preparation method to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a pre-hardened mold steel alloy and its preparation method, which can replace mold steel 1.2343. It can be pre-hardened to 44-46HRC and then directly processed into finished mold products, saving the cost and time of vacuum heat treatment, and reducing the mold manufacturing cycle and cost.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a pre-hardened mold steel alloy, the innovation of which is that the alloy chemical composition and its mass percentage of the pre-hardened mold steel alloy are: carbon 0.40~0.50%, silicon 0.20~0.40%, manganese 1.20~1.60%, sulfur ≤0.010%, phosphorus ≤0.025%, chromium 1.50~1.80%, molybdenum 0.35~0.50%, vanadium 0.15~0.25%, nickel 1.65~1.85%, copper ≤0.20%, iron as the balance, and the residual gas content is nitrogen ≤70ppm, hydrogen ≤1.0ppm, and oxygen ≤20ppm.

[0007] Furthermore, the alloy chemical composition and its mass percentage of the pre-hardened mold steel alloy are as follows: carbon 0.45%, silicon 0.30%, manganese 1.30%, sulfur 0.002%, phosphorus 0.020%, chromium 1.60%, molybdenum 0.40%, vanadium 0.15%, nickel 1.80%, with iron as the balance.

[0008] The preparation method of the above-mentioned pre-hardened mold steel alloy includes the following steps: S1. The pre-hardened mold steel is batched, smelted and refined in an electric arc furnace according to its alloy chemical composition and mass percentage, and then cast into steel ingots after vacuum degassing. The steel ingots are then subjected to high-temperature diffusion heat treatment. S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn to obtain a forging billet. The forging billet is then cooled and sent to an annealing furnace for annealing. After annealing, it is sent to a heating furnace for heating and holding. After holding, it is taken out of the furnace and cooled. Then it is sent to a tempering furnace for tempering. After tempering, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finely machined, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, with the bottom of the finished mold part immersed in the oil in the oil tank. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained.

[0009] Furthermore, the mold precision-machined part has a cavity inside, and two openings connecting the cavity are opened at both ends in the axial direction of the mold precision-machined part. The two openings are circular and coaxial with the mold precision-machined part. A flange is coaxially provided on the outside of the mold precision-machined part, and several flange holes are evenly distributed on the flange pitch circle of the flange.

[0010] Furthermore, the suspension device includes a suspension bracket located above the oil tank and two tie rods for pulling the precision-machined mold parts to rotate; The precision-machined mold part is rotatably suspended on the suspension bracket. The suspension bracket is driven to move downward by the second lifting drive mechanism, so that the bottom of the precision-machined mold part is immersed in the oil in the oil tank. The oil in the oil tank enters the interior of the precision-machined mold part through the openings at both ends of the precision-machined mold part. The bottom of the suspension bracket has a limiting plate to prevent the suspension bracket from being immersed in the oil in the oil tank. The two tie rods are respectively set on both sides of the flange hole of the mold precision machining part. The two tie rods are driven by the reciprocating mechanism to move back and forth between the initial station and the forward station, and cooperate with the cam mechanism to switch alternately between the first state and the second state. When one tie rod is in the first state, the other tie rod is in the second state. In the first state, the tie rod extends into the flange hole to connect the mold finishing part and moves from the initial station to the forward station. The tie rod applies a thrust to the mold finishing part, pushing the mold finishing part to rotate around the axis. In the second state, the pull rod disengages from the flange hole and unlocks from the finished mold part, and moves from the forward station to the initial station.

[0011] Furthermore, the suspension bracket includes a first lifting upright, a translation bracket, and two suspension support rollers; The top of the first lifting pole is connected to the translation bracket via a connecting rod. Two suspension support rollers are rotatably installed on the bottom of the first lifting pole and the translation bracket, respectively. The first lifting pole is driven to move up and down by the first lifting drive mechanism, and drives the connected suspension support rollers to move up and down synchronously. The translation bracket is driven to move horizontally by the lateral drive mechanism, and drives the connected suspension support rollers to move synchronously. The two suspension support rollers are respectively arranged on both sides of the mold precision-machined part and extend into the mold precision-machined part from the opening on the same side of the mold precision-machined part to support the top of the mold precision-machined part. The suspension support rollers have a limiting annular boss for limiting the position of the mold precision-machined part.

[0012] Furthermore, the reciprocating mechanism includes A fixed support is connected to a translational support and moves synchronously with the translational support; Two longitudinal translation components are provided, each corresponding to a tie rod. Each longitudinal translation component includes a longitudinal translation box and a second lifting column. The longitudinal translation box is movably mounted on a fixed bracket via a longitudinal guide rail assembly. The top of the second lifting column is movably mounted on the longitudinal translation box via a fixed slider. A flange receiving space is formed between the second lifting columns of the two longitudinal translation components to allow the flange of the precision-machined mold part to enter. The tie rod is installed at the bottom of the second lifting column of the corresponding longitudinal translation component. A rotating gear is mounted vertically on a fixed support with its central axis rotating vertically. The longitudinal translation boxes of two longitudinal translation components are respectively set on both sides of the rotating gear and are connected to the rotating gear through racks. The rotating gear is driven by a first rotating drive to rotate alternately in both directions and moves the longitudinal translation boxes through the racks. The longitudinal translation boxes move back and forth between the initial position and the forward position through a fixed slider and a second lifting rod.

[0013] Furthermore, the longitudinal translation component also includes a support rod and a support block. The support block is detachably mounted on a fixed bracket. The top surface of the support block has an arc-shaped support surface that matches the pitch circle contour of the flange of the precision-machined mold part. The top of the support rod is mounted on the second lifting upright, and the bottom end of the support rod is in contact with the arc-shaped support surface. The top surface of the support block has two waiting stations, which are respectively set on both sides of the arc-shaped support surface. Each of the two waiting stations on the top surface of the support block has a temporary positioning groove formed by an arc-shaped concave surface, which allows the bottom end of the support rod to enter. The bottom end of the arc-shaped concave surface is higher than the top end of the arc-shaped support surface. The arc-shaped concave surface is connected to the arc-shaped support surface through a smooth transition surface. The connection between the arc-shaped support surface and the smooth transition surface on both sides forms two station positioning slots, which correspond to the initial station and the forward station, respectively.

[0014] Furthermore, the cam mechanism includes two cam assemblies that correspond one-to-one with the longitudinal translation assembly; The cam assembly includes a cam and a sleeve. The central axis of the cam is vertically mounted on the side away from the flange accommodating space on the corresponding second lifting column and is driven to rotate by the second rotary drive component. The sleeve is mounted on the second lifting column. The pull rod is movably mounted in the sleeve by a spring. The tail end of the pull rod abuts against the cam profile surface under the action of the spring force. The front end of the pull rod extends out from the sleeve and reciprocates between the unlocked position and the locked position as the cam rotates. Furthermore, the cam has a closed profile line, which includes a circular arc segment and an arc segment. The outer diameter of the arc segment is larger than that of the circular arc segment. The two ends of the arc segment are smoothly connected to the two ends of the circular arc segment. The connection points between the two ends of the arc segment and the circular arc segment correspond to the initial working position and the forward working position, respectively, and are on the same straight line as the rotation center of the cam. When the front end of the pull rod is in the locked position, the tail end of the pull rod abuts against the arc-shaped section of the cam, and the front end of the pull rod enters the flange hole of the precision-machined mold part and connects with the precision-machined mold part; When the front end of the pull rod is in the unlocked position, the tail end of the pull rod abuts against the arc segment of the cam, and the front end of the pull rod leaves the flange hole of the mold precision-machined part, thus unlocking from the mold precision-machined part.

[0015] The advantages of this invention are: The pre-hardened mold steel alloy of this invention, through the composite addition and synergistic effect of various alloying elements, is directly pre-hardened to 44-46 HRC after smelting, forging, annealing and tempering heat treatment. At the same time, it has good machinability and can be directly machined into finished mold products without the need for secondary quenching, saving the cost and time of vacuum heat treatment. The cost of the pre-hardened mold steel alloy is lower than that of mold steel 1.2343, and it can replace mold steel 1.2343, with great performance advantages and competitive advantages.

[0016] The suspension device of this invention supports the precision-machined mold part by suspension. The bottom of the precision-machined mold part is immersed in the oil in the oil tank. Two tie rods apply radial force to the precision-machined mold part in sequence, causing the precision-machined mold part to rotate continuously. This allows the inner and outer surfaces of the precision-machined mold part to be immersed in the oil in the oil tank in sequence for oil adhesion. As the precision-machined mold part rotates, the entire inner and outer surface treatment of the precision-machined mold part is completed. Furthermore, the thickness of the oil film formed on the precision-machined mold part can be controlled by controlling the rotation speed and the number of rotations of the precision-machined mold part. The device is easy to operate and has an excellent surface anti-rust treatment effect.

[0017] The two tie rods of the suspension device of the present invention are driven by a reciprocating mechanism to move back and forth between the initial position and the forward position, and cooperate with the cam mechanism to quickly switch between the first state and the second state, forming a working mode in which the two tie rods alternately pull the mold precision part to rotate, avoiding the situation of the mold precision part rotating and slipping, realizing the uninterrupted continuous and stable rotation of the mold precision part, thereby ensuring the uniformity of the forming oil film on the surface of the mold precision part.

[0018] During the surface treatment process, the suspension device of the present invention generates relative flow between the mold precision-machined part and the oil in the oil tank as the mold precision-machined part rotates. Therefore, the oil tank does not need to provide additional power to make the oil flow, and the oil can achieve the effect of uniform adhesion, effectively reducing energy consumption and reducing oil waste. Attached Figure Description

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 This is a schematic diagram of the suspension device of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the suspension support roller of the present invention. Figure 3 This is a schematic diagram of the reciprocating mechanism of the present invention.

[0022] Figure 4 This is a schematic diagram of the support block of the present invention.

[0023] Figure 5 This is a schematic diagram of the cam mechanism of the present invention.

[0024] Figure 6 This is a schematic diagram of the cam structure of the present invention.

[0025] Figure 7 This is a diagram illustrating the process by which the suspension device of the present invention drives the precision-machined mold part to rotate.

[0026] Figure 8 This is a cross-sectional view of the finished mold part of the present invention.

[0027] Figure 9 This is an end face view of the precision-machined part of the mold according to the present invention. Detailed Implementation

[0028] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0029] This embodiment provides a pre-hardened mold steel alloy with the following alloy chemical composition and mass percentage: carbon 0.45%, silicon 0.30%, manganese 1.30%, sulfur 0.002%, phosphorus 0.020%, chromium 1.60%, molybdenum 0.40%, vanadium 0.15%, nickel 1.80%, and iron as the balance; the hardness is 46 HRC.

[0030] The preparation method of this pre-hardened mold steel alloy includes the following steps: S1. According to the alloy chemical composition and mass percentage of the pre-hardened mold steel, the materials are batched, smelted and refined in an electric arc furnace, and then cast into steel ingots after vacuum degassing. The steel ingots are subjected to high-temperature diffusion heat treatment and held at 1200℃ for 15 hours. S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn, with an upsetting ratio of 2.5 each time and a total forging ratio of 7.5. The final forging temperature is 900℃ to obtain a forging billet. The forging billet is then air-cooled and then sent to an annealing furnace for annealing treatment. The heating temperature is 600℃ and the holding temperature is 35h. After the annealing treatment, it is sent to a heating furnace to be heated to 980℃ and held for 20h. After the holding temperature is completed, it is taken out of the furnace and cooled to a surface temperature of 180℃. Then it is sent to a tempering furnace for tempering, heated to 550℃ and held for 30h. After the tempering is completed, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finished, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, and the bottom of the finished mold part is immersed in the oil in the oil tank. The oil used is rust-preventive oil. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained.

[0031] like Figure 8-9 As shown, the mold precision-machined part 1 has a cavity inside. Two openings connecting the cavity are opened at both ends of the mold precision-machined part 1 in the axial direction. The two openings are circular and coaxial with the mold precision-machined part 1. The two openings are one large and one small. A flange 101 is provided coaxially on the outside of the larger opening of the mold precision-machined part 1. Twelve flange holes 102 are evenly distributed on the flange pitch circle D of the flange 101.

[0032] The suspension device used in this embodiment, such as Figure 1 As shown, it includes a suspension bracket 3 located above the oil tank 2 and two pull rods 4 for pulling the mold finishing part 1 to rotate.

[0033] The central axis of the precision-machined mold part 1 is horizontally and rotatably suspended on the suspension bracket 3. The bottom of the precision-machined mold part 1 is immersed in the oil in the oil tank 2. The oil in the oil tank 2 enters the interior of the precision-machined mold part 1 through the openings at both ends of the precision-machined mold part 1. Two tie rods 4 are respectively set on both sides of the flange hole 102 of the precision-machined mold part 1. The two tie rods 4 are driven by the reciprocating mechanism 5 to move back and forth between the initial station A and the forward station B, and cooperate with the cam mechanism 6 to alternately switch between the first state and the second state. When one tie rod is in the first state, the other tie rod is in the second state. In the first state, the pull rod 4 extends into the flange hole 102 to connect the mold finishing part 1, and moves from the initial station A to the forward station B. The pull rod 4 applies a thrust to the mold finishing part 1, pushing the mold finishing part 1 to rotate around the axis. In the second state, the pull rod 4 is released from the flange hole 102 and unlocked from the mold finishing part 1, and moves from the forward station B to the initial station A.

[0034] In this embodiment, the suspension bracket 3 includes a first lifting upright 301, a translation bracket 302, and two suspension support rollers 305. The top of the first lifting upright 301 is connected to the translation bracket 302 via a connecting rod 303. The two suspension support rollers 305 are rotatably mounted on the bottom of the first lifting upright 301 and the translation bracket 302 respectively via bearings. The central axes of the two suspension support rollers 305 are horizontally arranged and are on the same vertical plane. Figure 2 As shown, each of the two suspension support rollers 305 has a limiting annular boss 3051 on one side away from each other. When the mold finishing part 1 is suspended, the two suspension support rollers 305 are respectively set on both sides of the mold finishing part 1 and extend into the interior of the mold finishing part 1 from the opening on the same side of the mold finishing part 1 to support the top of the mold finishing part 1. The two sides of the mold finishing part 1 are limited by the limiting annular bosses 3051 on the two suspension support rollers 305 to prevent the mold finishing part 1 from moving axially. When the mold finishing part 1 rotates, the friction force drives the suspension support rollers 305 to rotate relative to each other. This design can effectively avoid the situation of scratching the oil film on the inner wall of the mold finishing part 1 and ensure the uniformity of the oil film adhesion on the surface of the mold finishing part 1.

[0035] In this embodiment, the suspension bracket 3 is driven to move up and down by a second lifting drive mechanism. The second lifting drive mechanism is a telescopic electric drum, which is installed on a truss. The suspension bracket 3 is connected to the steel wire rope of the telescopic electric drum. The bottom of the suspension bracket 3 has a limiting plate 306 to prevent the suspension bracket 3 from being immersed in the oil in the oil tank. The limiting plate 306 is an L-shaped plate that matches the corner of the oil tank. When the mold precision part 1 is installed on the suspension bracket 3, the telescopic electric drum lowers the steel wire rope so that the bottom of the mold precision part 1 is immersed in the oil in the oil tank 2. When the limiting plate 306 abuts against the corner of the oil tank, the suspension bracket 3 stops moving down, thereby preventing the suspension bracket from moving down excessively and immersing itself in the oil in the oil tank 2.

[0036] In this embodiment, the first lifting pole 301 is driven to move up and down by the first lifting drive mechanism, and drives the connected suspension support roller 305 to move up and down synchronously. The translation bracket 302 is driven to move horizontally by the lateral drive mechanism, and drives the connected suspension support roller 305 to move synchronously.

[0037] The first lifting drive mechanism includes a protective box 3011, a first vertical slider, a first vertical slide rail, and a first linear drive component 3012. The protective box 3011 is vertically installed at the end of the connecting rod 303. The first vertical slider is fixedly installed inside the protective box. The first lifting rod 301 is vertically installed below the protective box 3011. The top of the first lifting rod 301 passes through the bottom of the protective box 3011 and enters the interior of the protective box 3011. One side of the first vertical slide rail is fixedly connected to the first lifting rod 301, and the other side is slidably connected to the first vertical slider. The first linear drive component 3012 is installed on the outer wall of the protective box. The telescopic end of the first linear drive component 3012 is connected to the bottom of the first lifting rod 301. The telescopic end of the first linear drive component 3012 drives the first lifting rod 301 to move up and down, thereby adjusting the height of the suspension support roller 305 installed on the first lifting rod 301.

[0038] The translation bracket 302 has an L-shaped structure and is located below the connecting rod 303. The lateral drive mechanism includes a first lateral slider 3021, a first lateral guide rail 3022, and a second linear drive member 3023. The first lateral guide rail 3022 is horizontally installed at the bottom of the connecting rod 303, and its extension direction is parallel to the central axis of the suspension support roller 305. The first lateral slider 3021 is fixedly installed on the top of the translation bracket 302 and is slidably connected to the first lateral guide rail 3022. The second linear drive member 3023 is installed on the translation bracket 302, and its telescopic end is connected to the connecting rod 303 through a connecting seat. When the telescopic end of the second linear drive member 3023 moves, it drives the translation bracket 302 to move horizontally along the first lateral guide rail 3022, thereby adjusting the distance between the suspension support roller installed on the translation bracket 302 and the other suspension support roller.

[0039] In this embodiment, the reciprocating mechanism 5 includes a fixed bracket 501, two longitudinal translation components corresponding one-to-one with the tie rod 4, and a rotary gear 502, as shown below. Figure 3 As shown.

[0040] A fixed bracket 501 is disposed between the first lifting upright 301 and the sliding bracket 302. The fixed bracket 501 includes a vertical rod and a Z-shaped rod. The top of the vertical rod is movably connected to the connecting rod 303 via a transverse guide mechanism. The transverse guide mechanism includes a second transverse guide rail 5011 and a second transverse slider 5012. The second transverse guide rail 5011 is horizontally installed at the bottom of the connecting rod 303, and its extension direction is parallel to the first transverse guide rail 3022. The second transverse slider 5012 is fixedly installed at the top of the vertical rod and slidably connected to the second transverse guide rail 5011. The top of the Z-shaped rod is fixedly connected to the vertical rod, and the bottom of the Z-shaped rod is fixedly connected to the sliding bracket 302.

[0041] The longitudinal translation component is mounted on the fixed bracket 501 and positioned between the vertical rod and the Z-shaped rod. When the translation bracket 302 moves horizontally, the longitudinal translation component moves synchronously via the fixed bracket 501. The longitudinal translation component includes a longitudinal translation box 502, a second lifting upright 503, a support rod 504, and a support block 505.

[0042] The longitudinal translation box 502 is movably mounted on the fixed bracket 501 via a longitudinal guide rail assembly. The longitudinal guide rail assembly includes a longitudinal slider 5021 and a longitudinal guide rail 5022. The longitudinal guide rail 5022 is horizontally fixed on the fixed bracket 501. The extension direction of the longitudinal guide rail 5022 is perpendicular to the central axis of the suspension support roller 305. One side of the longitudinal slider 5021 is fixedly connected to the longitudinal translation box 502, and the other side is slidably mounted on the longitudinal guide rail 5022.

[0043] The second lifting column 503 is vertically positioned, with its top extending into the longitudinal translation box 502. It is movably mounted on the longitudinal translation box 502 via a fixed slider 5031, which is fixedly installed on the longitudinal translation box 502. The second lifting column 503 has a vertically positioned second vertical slide rail that matches the fixed slider 5031, and the second vertical slide rail is slidably connected to the fixed slider 5031. A flange receiving space is formed between the second lifting columns 503 of the two longitudinal translation components, allowing the flange 101 of the mold finishing part 1 to enter. A pull rod 4 is installed at the bottom of the second lifting column 503 of the corresponding longitudinal translation component. When the pull rod 4 pulls the mold finishing part 1 to rotate, in addition to longitudinal horizontal displacement, vertical displacement also occurs along the movement trajectory of the pull rod 4. The movable design of the second lifting column 503 allows it to rise and fall synchronously with the pull rod 4, thus avoiding movement obstruction.

[0044] The support block 505 is located below the longitudinal guide rail 5022 and is detachably mounted on the fixed bracket 501 by bolts, as shown below. Figure 4 As shown, the top surface of the support block 505 has an arc-shaped support surface 505a that matches the profile of the flange pitch circle D of the mold precision-machined part 1. The top of the support rod 504 extends into the longitudinal translation box 502 and is fixedly installed on the second lifting column 503. The bottom end of the support rod 504 is in contact with the arc-shaped support surface 505a. When the pull rod 4 pulls the mold precision-machined part 1 to rotate, the support block 505 replaces the pull rod 4 to bear the weight of the second lifting column 503, so as to avoid the pull rod 4 from deforming and affecting the positional accuracy of the mold precision-machined part 1.

[0045] The top surface of the support block 505 has two waiting stations, which are respectively set on both sides of the arc-shaped support surface 505a. Each of the two waiting stations on the top surface of the support block 505 has a temporary positioning groove formed by an arc-shaped concave surface 505b, which allows the bottom end of the support rod 504 to enter. The bottom end of the arc-shaped concave surface 505b is higher than the top end of the arc-shaped support surface 505a. When the device is idle or when the mold is being precision machined, the support rod 504 can be pulled to move into the temporary positioning groove. At this time, the pull rod 4 at the bottom of the support rod 504 moves upward away from the suspension support roller 305, which facilitates the installation of the precision machined mold on the suspension support roller 305 and avoids the precision machined mold 1 from colliding with the pull rod 4 when suspended. In this embodiment, the arc-shaped concave surface 505b is connected to the arc-shaped support surface 505a through the smooth transition surface 505c. Two station positioning grooves A1 and B1 are formed at the connection between the arc-shaped support surface 505a and the smooth transition surface 505c. The two station positioning grooves A1 and B1 correspond to the initial station A and the forward station B, respectively. After the mold precision-machined part 1 is suspended and installed, the support rod 504 can be moved to the station positioning grooves A1 or B1 on both sides of the arc-shaped support surface 505a as required. The support rod 504 is driven by the second lifting upright 503 to move the pull rod 4 to the initial station A or the forward station B, which facilitates precise positioning with the flange hole of the mold precision-machined part at the station.

[0046] The rotating gear 506 is vertically mounted on the fixed bracket 501 with its central axis rotating vertically. The longitudinal translation boxes 502 of the two longitudinal translation components are respectively located on both sides of the rotating gear 506 and are connected to the rotating gear 506 via racks 507. The rotating gear 506 is driven by the first rotating drive 508 to rotate alternately in both directions, and drives the longitudinal translation boxes 502 to move horizontally along the longitudinal guide rail 5022 via the racks 507. The longitudinal translation boxes 502 drive the pull rods 4 to reciprocate between the initial position A and the forward position B via the fixed slider 5031 and the second lifting rod 503. The design of the rotating gear 506 allows for the synchronous movement of the two longitudinal translation components using only one drive, achieving precise control of the two pull rods 4 moving in opposite directions but with the same distance.

[0047] In this embodiment, the cam mechanism 6 includes two cam assemblies that correspond one-to-one with the longitudinal translation assembly; such as Figure 5As shown, the cam assembly includes a cam 601 and a sleeve 602. The central axis of the cam 601 is vertically mounted on the side of the corresponding second lifting column 503 away from the flange accommodating space, and is driven to rotate by the second rotary drive member 604. The second rotary drive member 604 is mounted on the second lifting column 503 through a mounting plate 605. The cam 601 is located below the mounting plate 605 and is connected to the rotating end of the second rotary drive member 604. The sleeve 602 is mounted on the second lifting column 503. The pull rod 4 is movably mounted in the sleeve 602 through a spring 603. The pull rod 4 is horizontally arranged and parallel to the central axis of the suspension support roller 305. The spring 603 is located in the sleeve 602 and sleeved on the outside of the pull rod 4. The two ends of the spring 603 abut against the pull rod 4 and the inner wall of the sleeve 602, respectively. The tail end of the pull rod 4 abuts against the contour surface of the cam 601 under the elastic force of the spring 603. The front end of the pull rod 4 extends out from the sleeve 602 and reciprocates between the unlocked and locked positions as the cam 601 rotates. The cam mechanism uses the cam and the spring to control the lateral movement of the pull rod 4, thereby precisely controlling the timing of the pull rod 4 moving into the flange hole to connect the precision-machined part 1 of the mold.

[0048] In this embodiment, the cam 601 has a closed profile, such as... Figure 6 As shown, the contour line includes a circular arc segment 601b and an arc segment 601a. ​​The outer diameter of the arc segment 601a is larger than the outer diameter of the circular arc segment 601b. The two ends of the arc segment 601a are smoothly connected to the two ends of the circular arc segment 601b. The connection points A2 and B2 between the two ends of the arc segment 601a and the circular arc segment 601b correspond to the initial station A and the forward station B, respectively. The connection points A2 and B2 between the two ends of the arc segment 601a and the circular arc segment 601b are on the same straight line as the rotation center of the cam 601.

[0049] When the front end of the pull rod 4 is in the locked position, the tail end of the pull rod 4 abuts against the arc-shaped section 601a of the cam 601, and the front end of the pull rod 4 enters the flange hole 102 of the mold precision part 1 and connects with the mold precision part 1. When the front end of the pull rod 4 is in the unlocked position, the tail end of the pull rod 4 abuts against the arc segment 601b of the cam 601, and the front end of the pull rod 4 leaves the flange hole 102 of the mold precision part 1, thus unlocking from the mold precision part 1.

[0050] When the precision-machined mold part 1 is suspended and installed, after the support rod 504 moves to the positioning slots A1 or B1 on both sides of the arc-shaped support surface 505a, the cam can be rotated according to the state requirements to adjust the pull rod to A2 or B2, thereby completing the lateral position adjustment between the pull rod and the flange hole of the precision-machined mold part. Subsequently, only the second rotary drive needs to be activated to control the rotation direction of the cam 601, so that the tail end of the pull rod can quickly move to the arc-shaped segment 601a or to the circular arc segment 601b to meet the state requirements. The cam 601 is composed of a closed contour line formed by the circular arc segment 601b and the arc-shaped segment 601a, and the connection points between the two ends of the arc-shaped segment 601a and the circular arc segment 601b are on the same straight line as the rotation center of the cam 601. This allows the second rotary drive to achieve the reciprocating movement of the pull rod in the lateral direction by rotating at a constant angular velocity in one direction, thereby realizing the automatic switching of the pull rod between the locked and unlocked positions.

[0051] In this embodiment, the first linear drive 3012 and the second linear drive 3023 are pneumatic cylinders, hydraulic cylinders or electric push rods, and the first rotary drive 508 and the second rotary drive 604 can be servo motors. All drive components are controlled by the controller that is matched with the suspension device.

[0052] The detailed process of suspending the precision-machined mold part above the oil tank using a suspension device and continuously rotating the precision-machined mold part, causing the oil in the oil tank to gradually adhere to the inner and outer surfaces of the precision-machined mold part to form an oil film, is as follows: Installation of the precision-machined mold parts: Adjust the suspension bracket of the suspension device to the required height. At this time, the two support rods 504 are respectively located in the temporary positioning grooves on the corresponding support blocks. The tie rod 4 is raised away from the suspension support roller 305. The side of the precision-machined mold part 1 with the flange is suspended on the suspension support roller on the translation bracket 302. The translation bracket 302 moves laterally, driving the precision-machined mold part 1 closer to the lifting pole 301. The suspension support roller of the lifting pole 301 extends into the interior from the other side of the precision-machined mold part 1 to support the precision-machined mold part. The lifting pole 301 moves up and down, adjusting the tilt angle of the precision-machined mold part to make the central axis of the precision-machined mold part horizontal. Initial positioning of the pull rods: Rotate the two cams 601 so that the two pull rods 4 are at the connection between the arc segment and the circular arc segment of the corresponding cam. One pull rod is located at A2 of the corresponding cam, and the other pull rod is located at B2 of the corresponding cam. Then, the two support rods 504 are moved out of the temporary positioning groove and moved to the work position positioning groove on the corresponding support block 505. One support rod is located in the work position positioning groove A1, and the other support rod is located in the work position positioning groove B1. At this time, the two pull rods are located at the initial work position A and the forward work position B respectively, and both are in the unlocked position. Surface treatment of mold precision parts: The suspension bracket moves the mold precision parts downward, immersing the bottom of the mold precision parts in the oil tank. At the same time, the first rotary drive and two second rotary drive components are activated. The two pull rods work together to drive the mold precision parts to rotate around the axis. By controlling the rotation speed and number of rotations of the mold precision parts, the thickness of the forming oil film on the mold precision parts is adjusted to meet the rust prevention requirements of the mold precision parts. After the surface treatment is completed, the suspension bracket rises, allowing the mold precision parts to leave the oil tank. The coordinated action of the two levers is as follows: like Figure 7 As shown, the first rotary drive rotates forward, and the pull rod located at the initial station A enters the first state. The tail end of the pull rod moves along the arc segment 601a of the cam 601, and the pull rod 4 moves from the unlocked position to the locked position. The front end of the pull rod enters the flange hole corresponding to the initial station A of the mold finishing part, and moves from the initial station A to the forward station B. The pull rod applies a radial force to the mold finishing part 1, causing the mold finishing part to rotate around the axis. When the pull rod reaches the forward station B, the pull rod returns from the locked position to the unlocked position. At the same time, the pull rod located at the forward station B enters the second state. The tail end of the pull rod moves along the arc segment 601a of the cam 601, and the pull rod remains in the unlocked position, and moves from the forward station B to the initial station A. The first rotary drive rotates in reverse, repeating the above process, and the mold finishing part continues to rotate.

[0053] During the surface treatment of the mold precision-machined parts, the two tie rods of the suspension device are driven by a reciprocating mechanism to move back and forth between the initial station and the forward station. They cooperate with the cam mechanism to quickly switch between the first and second states, forming a working mode in which the two tie rods alternately pull the mold precision-machined parts to rotate. This avoids slippage during the rotation of the mold precision-machined parts and achieves uninterrupted, continuous, and stable rotation of the mold precision-machined parts. This ensures the uniformity of the forming oil film on the surface of the mold precision-machined parts. Furthermore, as the mold precision-machined parts rotate, relative flow occurs between the mold precision-machined parts and the oil in the oil tank. Therefore, the oil tank does not need to provide additional power to make the oil flow, and the effect of uniform oil adhesion can still be achieved, effectively reducing energy consumption and reducing oil waste.

[0054] Example 2 This embodiment provides a pre-hardened mold steel alloy with the following alloy chemical composition and mass percentage: carbon 0.40%, silicon 0.10%, manganese 1.20%, sulfur 0.001%, phosphorus 0.001%, chromium 1.50%, molybdenum 0.35%, vanadium 0.20%, nickel 1.65%, copper 0.20%, and iron as the balance; the residual gas content is nitrogen 15ppm, hydrogen 0.2ppm, oxygen 11ppm, and the hardness is 44HRC.

[0055] The preparation method of this pre-hardened mold steel alloy includes the following steps: S1. According to the alloy chemical composition and mass percentage of the pre-hardened mold steel, the materials are batched, smelted and refined in an electric arc furnace, and then cast into steel ingots after vacuum degassing. The steel ingots are subjected to high-temperature diffusion heat treatment and held at 1200℃ for 15 hours. S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn, with an upsetting ratio of 2.5 each time and a total forging ratio of 7.5. The final forging temperature is 900℃ to obtain a forging billet. The forging billet is then air-cooled and then sent to an annealing furnace for annealing treatment. The heating temperature is 600℃ and the holding temperature is 35h. After the annealing treatment, it is sent to a heating furnace to be heated to 980℃ and held for 20h. After the holding temperature is completed, it is taken out of the furnace and cooled to a surface temperature of 180℃. Then it is sent to a tempering furnace for tempering, heated to 550℃ and held for 30h. After the tempering is completed, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finished, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, and the bottom of the finished mold part is immersed in the oil in the oil tank. The oil used is rust-preventive oil. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained.

[0056] Example 3 This embodiment provides a pre-hardened mold steel alloy with the following alloy chemical composition and mass percentage: carbon 0.50%, silicon 0.40%, manganese 1.60%, sulfur 0.003%, phosphorus 0.025%, chromium 1.80%, molybdenum 0.50%, vanadium 0.25%, nickel 1.85%, copper 0.05%, and iron as the balance; the residual gas content is nitrogen 70ppm, hydrogen 0.98ppm, oxygen 19ppm, and the hardness is 44.9HRC.

[0057] The preparation method of this pre-hardened mold steel alloy includes the following steps: S1. According to the alloy chemical composition and mass percentage of the pre-hardened mold steel, the materials are batched, smelted and refined in an electric arc furnace, and then cast into steel ingots after vacuum degassing. The steel ingots are subjected to high-temperature diffusion heat treatment and held at 1200℃ for 15 hours. S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn, with an upsetting ratio of 2.5 each time and a total forging ratio of 7.5. The final forging temperature is 900℃ to obtain a forging billet. The forging billet is then air-cooled and then sent to an annealing furnace for annealing treatment. The heating temperature is 600℃ and the holding temperature is 35h. After the annealing treatment, it is sent to a heating furnace to be heated to 980℃ and held for 20h. After the holding temperature is completed, it is taken out of the furnace and cooled to a surface temperature of 180℃. Then it is sent to a tempering furnace for tempering, heated to 550℃ and held for 30h. After the tempering is completed, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finished, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, and the bottom of the finished mold part is immersed in the oil in the oil tank. The oil used is rust-preventive oil. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained.

[0058] Example 4 This embodiment provides a pre-hardened mold steel alloy with the following alloy chemical composition and mass percentage: carbon 0.48%, silicon 0.34%, manganese 1.50%, sulfur 0.002%, phosphorus 0.020%, chromium 1.70%, molybdenum 0.40%, vanadium 0.21%, nickel 1.79%, copper 0.01%, and iron as the balance; the residual gas content is nitrogen 0.1ppm, hydrogen 0.1ppm, and oxygen 0.5ppm; and the hardness is 45.2HRC.

[0059] The preparation method of this pre-hardened mold steel alloy includes the following steps: S1. According to the alloy chemical composition and mass percentage of the pre-hardened mold steel, the raw materials are batched, smelted and refined in an electric arc furnace, and then cast into steel ingots after vacuum degassing. The steel ingots are subjected to high-temperature diffusion heat treatment and held at 1250℃ for 20 hours. S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn, with an upsetting ratio of 3 for each time and a total forging ratio of 10. The final forging temperature is 890℃ to obtain a forging billet. The forging billet is then air-cooled and then sent to an annealing furnace for annealing treatment. The heating temperature is 650℃ and the holding temperature is 39h. After the annealing treatment, it is sent to a heating furnace to be heated to 1000℃ and held for 30h. After the holding temperature is completed, it is taken out of the furnace and cooled to a surface temperature of 150℃. Then it is sent to a tempering furnace for tempering, heated to 600℃ and held for 40h. After the tempering is completed, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finished, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, and the bottom of the finished mold part is immersed in the oil in the oil tank. The oil used is rust-preventive oil. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained.

[0060] Pre-hardened mold steel alloys, through the composite addition and synergistic effect of various alloying elements, are directly pre-hardened to 44-46 HRC after smelting, forging, annealing, and tempering heat treatment. They also possess excellent machinability, allowing direct cutting into finished mold products without secondary quenching, thus saving the cost and time of vacuum heat treatment. The cost of pre-hardened mold steel alloys is lower than that of mold steel 1.2343, making them a viable alternative with significant performance and competitive advantages.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a pre-hardened mold steel alloy, characterized in that: Includes the following steps: S1. The pre-hardened mold steel is batched, smelted and refined in an electric arc furnace according to its alloy chemical composition and mass percentage, and then cast into steel ingots after vacuum degassing. The steel ingots are then subjected to high-temperature diffusion heat treatment. The alloy chemical composition and mass percentage of the pre-hardened mold steel alloy are as follows: carbon 0.40~0.50%, silicon 0.20~0.40%, manganese 1.20~1.60%, sulfur ≤0.010%, phosphorus ≤0.025%, chromium 1.50~1.80%, molybdenum 0.35~0.50%, vanadium 0.15~0.25%, nickel 1.65~1.85%, copper ≤0.20%, with iron as the balance, and the residual gas content is nitrogen ≤70ppm, hydrogen ≤1.0ppm, and oxygen ≤20ppm; S2. The steel ingot after high-temperature diffusion heat treatment is upset and drawn to obtain a forging billet. The forging billet is then cooled and sent to an annealing furnace for annealing. After annealing, it is sent to a heating furnace for heating and holding. After holding, it is taken out of the furnace and cooled. Then it is sent to a tempering furnace for tempering. After tempering, it is taken out of the furnace and air-cooled to obtain a mold blank. S3. After the mold blank is roughed and then finely machined, a finished mold part is obtained. Then, the finished mold part is suspended above the oil tank using a suspension device, with the bottom of the finished mold part immersed in the oil in the oil tank. The suspension device drives the finished mold part to rotate continuously, so that the oil in the oil tank gradually adheres to the inner and outer surfaces of the finished mold part to form an oil film. By controlling the rotation speed and number of rotations of the finished mold part, the thickness of the formed oil film on the finished mold part is adjusted. When the oil film thickness reaches the required level, the finished mold part is suspended to drain, and the finished mold is obtained. The mold precision-machined part has a cavity inside, and two openings connecting the cavity are opened at both ends in the axial direction of the mold precision-machined part. The two openings are circular and coaxial with the mold precision-machined part. A flange is coaxially provided on the outside of the mold precision-machined part, and several flange holes are evenly distributed on the flange pitch circle of the flange. The suspension device includes a suspension bracket located above the oil tank and two pull rods for pulling the precision-machined mold parts to rotate; The precision-machined mold part is rotatably suspended on the suspension bracket. The suspension bracket is driven to move downward by the second lifting drive mechanism, so that the bottom of the precision-machined mold part is immersed in the oil in the oil tank. The oil in the oil tank enters the interior of the precision-machined mold part through the openings at both ends of the precision-machined mold part. The bottom of the suspension bracket has a limiting plate to prevent the suspension bracket from being immersed in the oil in the oil tank. The two tie rods are respectively set on both sides of the flange hole of the mold precision machining part. The two tie rods are driven by the reciprocating mechanism to move back and forth between the initial station and the forward station, and cooperate with the cam mechanism to switch alternately between the first state and the second state. When one tie rod is in the first state, the other tie rod is in the second state. In the first state, the tie rod extends into the flange hole to connect the mold finishing part and moves from the initial station to the forward station. The tie rod applies a thrust to the mold finishing part, pushing the mold finishing part to rotate around the axis. In the second state, the pull rod disengages from the flange hole and unlocks from the finished mold part, and moves from the forward station to the initial station.

2. The method for preparing the pre-hardened mold steel alloy according to claim 1, characterized in that: The suspension bracket includes a first lifting upright, a translation bracket, and two suspension support rollers; The top of the first lifting pole is connected to the translation bracket via a connecting rod. Two suspension support rollers are rotatably installed on the bottom of the first lifting pole and the translation bracket, respectively. The first lifting pole is driven to move up and down by the first lifting drive mechanism, and drives the connected suspension support rollers to move up and down synchronously. The translation bracket is driven to move horizontally by the lateral drive mechanism, and drives the connected suspension support rollers to move synchronously. The two suspension support rollers are respectively arranged on both sides of the mold precision-machined part and extend into the mold precision-machined part from the opening on the same side of the mold precision-machined part to support the top of the mold precision-machined part. The suspension support rollers have a limiting annular boss for limiting the position of the mold precision-machined part.

3. The method for preparing the pre-hardened mold steel alloy according to claim 2, characterized in that: The reciprocating mechanism includes A fixed support is connected to a translational support and moves synchronously with the translational support; Two longitudinal translation components are provided, each corresponding to a tie rod. Each longitudinal translation component includes a longitudinal translation box and a second lifting column. The longitudinal translation box is movably mounted on a fixed bracket via a longitudinal guide rail assembly. The top of the second lifting column is movably mounted on the longitudinal translation box via a fixed slider. A flange receiving space is formed between the second lifting columns of the two longitudinal translation components to allow the flange of the precision-machined mold part to enter. The tie rod is installed at the bottom of the second lifting column of the corresponding longitudinal translation component. A rotating gear is mounted vertically on a fixed support with its central axis rotating vertically. The longitudinal translation boxes of two longitudinal translation components are respectively set on both sides of the rotating gear and are connected to the rotating gear through racks. The rotating gear is driven by a first rotating drive to rotate alternately in both directions and moves the longitudinal translation boxes through the racks. The longitudinal translation boxes move back and forth between the initial position and the forward position through a fixed slider and a second lifting rod.

4. The method for preparing the pre-hardened mold steel alloy according to claim 3, characterized in that: The longitudinal translation component also includes a support rod and a support block. The support block is detachably mounted on a fixed bracket. The top surface of the support block has an arc-shaped support surface that matches the pitch circle contour of the flange of the precision-machined mold part. The top of the support rod is mounted on the second lifting upright, and the bottom end of the support rod is in contact with the arc-shaped support surface. The top surface of the support block has two waiting stations, which are respectively set on both sides of the arc-shaped support surface. Each of the two waiting stations on the top surface of the support block has a temporary positioning groove formed by an arc-shaped concave surface, which allows the bottom end of the support rod to enter. The bottom end of the arc-shaped concave surface is higher than the top end of the arc-shaped support surface. The arc-shaped concave surface is connected to the arc-shaped support surface through a smooth transition surface. The connection between the arc-shaped support surface and the smooth transition surface on both sides forms two station positioning slots, which correspond to the initial station and the forward station, respectively.

5. The method for preparing the pre-hardened mold steel alloy according to claim 4, characterized in that: The cam mechanism includes two cam assemblies that correspond one-to-one with the longitudinal translation assembly; The cam assembly includes a cam and a sleeve. The central axis of the cam is vertically mounted on the side away from the flange accommodating space on the corresponding second lifting column and is driven to rotate by a second rotary drive. The sleeve is mounted on the second lifting column. The pull rod is movably mounted in the sleeve by a spring. The tail end of the pull rod abuts against the cam profile surface under the action of the spring force. The front end of the pull rod extends out from the sleeve and reciprocates between the unlocked position and the locked position as the cam rotates.

6. The method for preparing the pre-hardened mold steel alloy according to claim 5, characterized in that: The cam has a closed profile line, which includes a circular arc segment and an arc segment. The outer diameter of the arc segment is larger than that of the circular arc segment. The two ends of the arc segment are smoothly connected to the two ends of the circular arc segment. The connection points between the two ends of the arc segment and the circular arc segment correspond to the initial working position and the forward working position, respectively, and are on the same straight line as the rotation center of the cam. When the front end of the pull rod is in the locked position, the tail end of the pull rod abuts against the arc-shaped section of the cam, and the front end of the pull rod enters the flange hole of the precision-machined mold part and connects with the precision-machined mold part; When the front end of the pull rod is in the unlocked position, the tail end of the pull rod abuts against the arc segment of the cam, and the front end of the pull rod leaves the flange hole of the mold precision-machined part, thus unlocking from the mold precision-machined part.

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