A piston casting mold and a piston casting method

Abstract

This invention discloses a piston casting mold and a piston casting method. The piston casting mold includes: a first outer mold and a second outer mold that are separately configured, with a mold cavity between the first and second outer molds. Each of the first and second outer molds has a limiting cavity near the mold cavity. A limiting part of the insert ring around its periphery is detachably installed in the limiting cavity to suspend the insert ring in the mold cavity; a fixing component installed in the limiting cavity to fix the limiting part of the insert ring; and a heating component installed on the first and / or second outer molds to heat the insert ring. The piston casting mold provided by this invention, through the setting of the fixing component, suspends and fixes the insert ring in the mold cavity, avoiding the existing method of positioning by clamping the mold cover and the outer mold. This effectively increases the temperature of the alloy liquid on the upper and lower end faces of the insert ring, improves the bonding quality of the insert ring, eliminates defects such as porosity on the lower end face of the insert ring, and improves the reliability and service life of the piston.

Description

Technical Field

[0001] This invention relates to the field of piston manufacturing technology, and in particular to a piston casting mold and piston casting method. Background Technology

[0002] As automotive diesel engines develop towards higher power, higher speed, and higher reliability, the requirements for piston quality are becoming increasingly stringent. In order to improve the corrosion and wear resistance of piston ring grooves, improve air tightness, reduce oil consumption, and improve diesel engine performance, aluminum-lined pistons are generally used.

[0003] In the existing technology, the ring positioning method involves placing the ring on the positioning table of the outer mold ring. When the piston blank is poured, the mold cover descends and presses down on the upper end face of the ring, while the lower end face of the ring contacts the positioning table of the outer mold ring, relying on the clamping and positioning by the mold cover and the outer mold. Alternatively, a placement groove is opened on the outer mold, and a heater is placed in the placement groove to increase the temperature around the ring, and ultimately avoid the risk of poor ring adhesion and white spots under the ring.

[0004] However, in the existing technology, the method of clamping and positioning the mold cover and the outer mold restricts the outer mold's gating structure. The mold cover blocks the possibility of pouring molten aluminum onto the upper end face of the insert ring. Therefore, the molten aluminum can only be formed on the lower end face of the insert ring through the existing gating system. The molten aluminum in this area is prone to backflow and turbulence, which can easily lead to defects such as shrinkage porosity and shrinkage cavities. At the same time, it can cause the insert ring temperature to be too low, which can easily lead to defects such as air holes. In addition, because the clamping and positioning method of the mold cover and the outer mold for the insert ring has low positioning accuracy, the insert ring may move on the positioning platform of the insert ring in the outer mold, causing the insert ring to shift.

[0005] Meanwhile, the method of opening a placement groove in the outer mold and placing a heater in the placement groove has a large contact area because the upper and lower protruding end faces of the existing structure ring contact the mold cover and the positioning platform of the outer mold ring respectively. In addition, the existing mold material is mold steel, which dissipates heat quickly. Therefore, the temperature of the ring cannot be maintained by heating in the outer mold placement groove, and it cannot effectively avoid the risk of poor ring adhesion and air holes around the piston ring.

[0006] Therefore, how to effectively reduce casting defects in piston blanks and improve the quality of piston rings and their surrounding areas is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a piston casting mold and piston casting method to improve the casting quality of pistons and extend their service life.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A piston casting mold, comprising:

[0010] The first outer mold and the second outer mold are set as separate parts. A mold cavity is provided between the first outer mold and the second outer mold. A limiting cavity is provided on the first outer mold and the second outer mold near the mold cavity. The limiting part of the insert ring around the periphery is detachably installed in the limiting cavity so that the insert ring is suspended in the mold cavity.

[0011] A fixing component is installed inside the limiting cavity to fix the insert limiting part;

[0012] A heating assembly, mounted on the first outer mold and / or the second outer mold, is used to heat the insert.

[0013] Preferably, the fixing component includes an elastic member and a positioning rod, one end of which abuts against the elastic member, and the other end of which abuts against the insert limiting part.

[0014] Preferably, the opening of the limiting cavity is provided with a stepped surface, and the positioning rod is provided with a stepped portion. The stepped portion of the positioning rod is engaged with the stepped surface to prevent the positioning rod from disengaging from the limiting cavity. The heating assembly includes a heating coil, which is wrapped around the stepped portion of the positioning rod.

[0015] Preferably, a sprue is provided between the first outer mold and the second outer mold. The sprue contains a sprue and a plurality of ingates connected to the sprue. The side of each ingate away from the sprue is connected to the mold cavity.

[0016] Preferably, each of the ingates is inclined downward from the mold cavity on the side closest to the sprue; and / or, the draft angle of the ingate relative to the horizontal direction is 30-35°.

[0017] Preferably, the ingate includes a first ingate, a second ingate, and a third ingate, wherein the area ratio of the cross-sectional areas of the first ingate, the second ingate, and the third ingate at their junctions with the mold cavity is S1:S2:S3 = 1:0.8~0.6:0.5~0.3; and the ingate structure design adopts the following formula:

[0018] H=P+E+D / 2; D=Q / 6; E=20+D; P=Q+D;

[0019] Where: H refers to the distance between the inner wall of the sprue cup away from the mold cavity and the mold cavity axis; P refers to the distance between the outer wall of the sprue cup near the mold cavity and the mold cavity axis; E refers to the diameter of the sprue cup opening; D refers to the distance between the bottom of the first ingate and the upper surface of the insert ring; Q refers to the piston cylinder diameter, Q=85-200mm.

[0020] Preferably, an outer mold positioning ring is provided at a preset position on the first outer mold and the second outer mold. A positioning part is provided on the outer mold positioning ring at a position corresponding to the limiting cavity. The inlay ring limiting part can pass through the positioning part and be inserted into the limiting cavity.

[0021] Preferably, it further includes an air supply component, wherein the first outer mold and / or the second outer mold are provided with a first air supply channel, one end of the first air supply channel is connected to the air supply component, and the other end is connected to the limiting cavity.

[0022] Preferably, the fixing component is further provided with a second air supply channel, one end of which is connected to the first air supply channel and the other end is connected to the mold cavity.

[0023] A piston casting method, using a piston casting mold as described above, includes the following steps:

[0024] Turn on the casting machine and heat the molten alloy for casting and the molten alloy for inlaying rings to the preset temperature, then transfer them to the casting station;

[0025] The first and second outer molds in the piston casting mold are controlled to automatically close, leaving a gap, and the heating assembly is activated;

[0026] Obtain the insert ring and place the insert ring limiting part of the insert ring into the limiting cavity of the first outer mold and the second outer mold;

[0027] The first outer mold and the second outer mold are automatically closed until the insert ring limiting part abuts against the fixing component;

[0028] The piston casting mold is tilted at an angle of B1 relative to the horizontal direction to cast the first region of the mold cavity; the tilt angle is adjusted to B2 to cast the second region of the mold cavity; the tilt angle is adjusted to B3 to cast the third region of the mold cavity; the first, second, and third regions are arranged from bottom to top; the tilt angle of the piston casting mold is slowly adjusted to B4 while casting continues until the sprue is full, and the piston casting mold is slowly leveled to complete the casting process; wherein the tilt angles B1, B2, B3, and B4 decrease sequentially.

[0029] Control the opening of the first outer mold and the second outer mold to remove the piston blank.

[0030] The piston casting mold provided by this invention includes: a first outer mold and a second outer mold that are separately configured, with a mold cavity between the first outer mold and the second outer mold, and limiting cavities on both the first outer mold and the second outer mold near the mold cavity. A limiting portion of the insert ring around its periphery is detachably installed in the limiting cavity, so that the insert ring is suspended in the mold cavity; a fixing component is installed in the limiting cavity for fixing the limiting portion of the insert ring; and a heating component is installed on the first outer mold and / or the second outer mold for heating the insert ring. The piston casting mold provided by this invention, through the setting of the fixing component, suspends and fixes the insert ring in the mold cavity, avoiding the existing method of positioning by clamping the mold cover and the outer mold. This effectively increases the temperature of the alloy liquid on the upper and lower end faces of the insert ring, improves the bonding quality of the insert ring, eliminates defects such as porosity on the lower end face of the insert ring, and improves the reliability and service life of the piston.

[0031] The piston casting method provided by this invention includes the following steps: turning on the casting machine, heating the casting alloy liquid and the ring-infiltrating alloy liquid to a preset temperature, and then transferring them to the casting station; controlling the first and second outer molds in the piston casting mold to automatically close, leaving a gap, and starting the heating component; obtaining the ring and placing the ring-limiting part of the ring in the limiting cavity of the first and second outer molds; controlling the first and second outer molds to automatically close until the ring-limiting part abuts against the fixing component; controlling the tilt angle of the piston casting mold relative to the horizontal direction to B1, and casting the first area of ​​the mold cavity; controlling the... The piston casting mold is tilted at an angle of B2 relative to the horizontal direction to cast the second region of the mold cavity; the tilt angle of the piston casting mold is then adjusted to B3 to cast the third region of the mold cavity; the first, second, and third regions are arranged from bottom to top; the tilt angle of the piston casting mold is slowly adjusted to B4 while continuing to pour until the sprue is full, and the piston casting mold is slowly leveled to complete the pouring; wherein the tilt angles B1, B2, B3, and B4 decrease sequentially; the first and second outer molds are opened to remove the piston blank. The piston casting method provided by this invention, by changing the casting method, utilizes the casting machine to tilt the piston casting mold, and during the casting process, the tilt angle gradually decreases, i.e., the piston casting mold gradually approaches horizontality from tilted, which can effectively improve the fluidity of the alloy liquid, avoid backflow of the alloy liquid at blockage points, prevent turbulence and backflow of the alloy liquid, and eliminate casting defects such as shrinkage porosity and shrinkage cavities on the upper surface of the sprue. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of a specific embodiment of the piston casting mold provided by the present invention;

[0034] Figure 2 for Figure 1 The diagram shows the cross-section AA of the piston casting mold.

[0035] Figure 3 for Figure 1 The diagram shows a cross-section of BB in the piston casting mold.

[0036] Figure 4 for Figure 1 The diagram shows a schematic of the CC section in the piston casting mold.

[0037] Figure 5 for Figure 2 The diagram shows a cross-section of EE in the piston casting mold.

[0038] Figures 6-1 to 6-6 This is a schematic diagram of the piston casting method provided by the present invention;

[0039] The components include: outer mold 1, first outer mold 11, second outer mold 12, outer mold positioning ring 13, insert ring 2, insert ring limiting part 21, fixing component 3, positioning ejector rod 31, elastic component 32, heating component 4, heating coil 41, heating wire tube 42, sprue 5, sprue 51, ingate 52, first ingate 521, second ingate 522, third ingate 523, pouring cup 53, air supply component 6, first air supply channel 61, second air supply channel 62, air inlet / outlet pipe connector 63, mold cover 7, and alloy liquid 8. Detailed Implementation

[0040] The core of this invention is to provide a piston casting mold and piston casting method, which can significantly improve the bonding quality between the insert and the piston body and eliminate defects such as air holes on the lower end face of the insert.

[0041] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Please refer to Figure 1 To Figure 6, Figure 1A schematic diagram of a specific embodiment of the piston casting mold provided by the present invention; Figure 2 for Figure 1 The diagram shows the cross-section AA of the piston casting mold. Figure 3 for Figure 1 The diagram shows a cross-section of BB in the piston casting mold. Figure 4 for Figure 1 The diagram shows a schematic of the CC section in the piston casting mold. Figure 5 for Figure 2 The diagram shows a cross-section of EE in the piston casting mold. Figures 6-1 to 6-6 This is a schematic diagram of the piston casting method provided by the present invention.

[0043] In this embodiment, such as Figure 1 As shown, the piston casting mold includes an outer mold 1 and a mold cover 7. The outer mold 1 includes a first outer mold 11 and a second outer mold 12, which are separately arranged. A mold cavity is provided between the first outer mold 11 and the second outer mold 12. A limiting cavity is provided on the first outer mold 11 and the second outer mold 12 near the mold cavity. The limiting part 21 of the insert ring 2 is detachably installed in the limiting cavity so that the insert ring 2 is suspended in the mold cavity. It also includes a fixing component 3 and a heating component 4. The fixing component 3 is installed in the limiting cavity to fix the limiting part 21 of the insert ring. The heating component 4 is installed on the first outer mold 11 and / or the second outer mold 12 to heat the insert ring 2.

[0044] Specifically, the first outer mold 11 and the second outer mold 12 are movable relative to each other. When the first outer mold 11 and the second outer mold 12 are closed, the mold cavity is combined into a complete mold cavity. The periphery of the insert ring 2 has an insert ring limiting part 21, which is a protruding structure protruding from the periphery. Preferably, there are two insert ring limiting parts 21, located on both sides of the diameter direction of the insert ring 2. The side of the insert ring limiting part 21 is provided with an angle to facilitate entry and exit from the limiting cavity. During installation, the insert ring limiting part 21 on one side of the insert ring 2 is first inserted into the limiting cavity of one of the first outer mold 11 and the second outer mold 12. The insert ring 2 is placed in the cavity, and then the insert ring limiting part 21 on the other side of the insert ring 2 is placed into the limiting cavity of the other of the first outer mold 11 and the second outer mold 12. The fixing component 3 is used to position the insert ring 2. Specifically, the insert ring 2 can be fixed by fixing the insert ring limiting part 21. The heating component 4 is installed on the first outer mold 11 and / or the second outer mold 12. It can be installed in the limiting cavity to heat the limiting cavity and its surrounding area, thereby heating the insert ring 2, increasing the temperature around the insert ring 2, and ultimately avoiding the risk of poor adhesion of the insert ring 2 and white spots under the ring. Furthermore, this mold can be used to process aluminum pistons, that is, to cast molten aluminum in the mold.

[0045] The piston casting mold provided by the present invention, through the setting of the fixing component 3, suspends and fixes the insert ring 2 in the mold cavity, avoiding the method of clamping and positioning by the mold cover 7 and the outer mold 1 in the prior art. It can effectively increase the temperature of the alloy liquid 8 on the upper and lower end faces of the insert ring 2, improve the bonding quality of the insert ring 2, eliminate defects such as air holes on the lower end face of the insert ring 2, and improve the reliability and service life of the piston.

[0046] In some embodiments, the fixing component 3 includes an elastic member 32 and a positioning push rod 31. One end of the positioning push rod 31 abuts against the elastic member 32, and the other end abuts against the insert ring limiting part 21. Specifically, during the installation of the insert ring 2, the insert ring limiting part 21 on one side of the insert ring 2 contacts the positioning push rod 31 of either the first outer mold 11 or the second outer mold 12, slowly compressing the elastic member 32. Then, the insert ring limiting part 21 on the other side of the insert ring 2 contacts the positioning push rod 31 of either the first outer mold 11 or the second outer mold 12, compressing the other elastic member 32. Under the action of the two elastic members 32, the insert ring 2 moves to the middle position between the first outer mold 11 and the second outer mold 12, achieving balance. At the same time, the elastic member 32 is forced against the positioning push rod 31, so that the positioning push rod 31 and both ends of the insert ring 2 are under stress, completing the installation process of the insert ring 2.

[0047] In some embodiments, the opening of the limiting cavity is provided with a stepped surface, and the positioning rod 31 is provided with a stepped portion. The stepped portion of the positioning rod 31 is engaged with the stepped surface to prevent the positioning rod 31 from disengaging from the limiting cavity. Specifically, the cooperation between the stepped portion of the positioning rod 31 and the stepped surface of the limiting cavity can prevent the positioning rod 31 from disengaging from the limiting cavity and ensure the stable pressing effect of the positioning rod 31 on the limiting cavity.

[0048] In some embodiments, the heating assembly 4 includes a heating coil 41, which is wound around the stepped portion of the positioning push rod 31. Specifically, the heating coil 41, wound around the stepped portion of the positioning push rod 31, transfers heat from the heating coil 41 to the insert ring limiting portion 21 via the positioning push rod 31, and then to the insert ring 2, thereby achieving the purpose of heating the insert ring 2. Further, the heating assembly 4 also includes a heating wire 42, which is connected to the heating coil 41 and used to supply power to the heating coil 41; the heating wire 42 passes through the first outer mold 11 and / or the second outer mold 12, and its two ends are respectively connected to the positive and negative terminals of the power supply.

[0049] In some implementations, such as Figure 2 and Figure 3As shown, it also includes a gating system 5, which contains a sprue 51 and several ingates 52 connected to the sprue 51. The side of each ingate 52 away from the sprue 51 is connected to the mold cavity. That is, each ingate 52 is connected to the mold cavity and is arranged at intervals along the longitudinal direction of the mold cavity. Specifically, the ingates 52 are located between the first outer mold 11 and the second outer mold 12 to achieve layered casting and avoid defects such as shrinkage porosity caused by turbulent flow of the alloy liquid 8.

[0050] In some embodiments, each ingate 52 is inclined downward from the side of the mold cavity closest to the sprue 51, thereby ensuring that the molten alloy 8 flows smoothly into the mold cavity, reducing the impact of the molten alloy 8, and thus preventing the molten alloy 8 from turbulent flow and backflow.

[0051] In some embodiments, the ingate 52 includes a first ingate 521, a second ingate 522, and a third ingate 523 arranged sequentially from top to bottom. Further, the first ingate 521 is connected to the mold cavity at the upper part of the insert 2, the second ingate 522 is connected to the mold cavity at the lower part of the insert 2, and the third ingate 523 is connected to the mold cavity at the bottom of the mold cavity, thereby achieving layered casting. It is particularly noteworthy that the positioning method of the insert 2 in this invention allows for the design of three ingates. Furthermore, by employing the three-ingate structure, the third ingate 523 provides molten aluminum, causing the temperature of the insert 2 to rise, thereby further increasing the temperature of the molten aluminum around the insert 2. This ensures smooth flow of the molten metal within the feeding channel, ultimately improving the piston quality.

[0052] Furthermore, the first ingate 521, the second ingate 522, and the third ingate 523 are all inclined relative to the horizontal direction, i.e., a three-section sprue design 51 is adopted. Simultaneously, inclined pouring is used to avoid defects such as shrinkage porosity caused by turbulent flow of the molten alloy 8 within the sprue 51. Preferably, the inclination angles of the first ingate 521, the second ingate 522, and the third ingate 523 relative to the horizontal direction are 10-15°, 8-10°, and 10-15° respectively, effectively reducing the impact velocity of the molten alloy 8 during casting and preventing turbulent flow of the molten alloy 8.

[0053] In some embodiments, the draft angle of the ingate 52 relative to the horizontal direction is 30-35°, which facilitates demolding. The aforementioned setting of the number and angle of the ingates 52 can alter the sequential solidification during the casting process, ensuring smooth flow of the molten alloy 8 within the feeding channels; achieving stable filling of the molten alloy 8 and preventing flow interruptions and confluences; under the premise of stable filling of the molten alloy 8, the inclined setting can increase the filling speed; it is beneficial for slag blocking and venting; it improves production efficiency, saves molten alloy 8, and facilitates the removal of risers and gating gates.

[0054] In some embodiments, the ingate 52 includes a first ingate 521, a second ingate 522, and a third ingate 523, with the cross-sectional areas of the first ingate 521, the second ingate 522, and the third ingate 523 decreasing sequentially. Specifically, the area ratio of the cross-sectional areas of the first ingate 521, the second ingate 522, and the third ingate 523 at their junctions with the mold cavity is S1:S2:S3 = 1:0.8~0.6:0.5~0.3; and the ingate structure design adopts the following formula:

[0055] H=P+E+D / 2; D=Q / 6; E=20+D; P=Q+D;

[0056] Among them: such as Figure 2 As shown, H refers to the distance between the inner wall of the sprue cup 53 away from the mold cavity and the mold cavity axis; P refers to the distance between the outer wall of the sprue cup 53 near the mold cavity and the mold cavity axis; E refers to the diameter of the sprue cup 53; D refers to the distance between the bottom of the first inner sprue 521 and the upper surface of the insert ring 2; Q refers to the piston cylinder diameter, Q=85-200mm.

[0057] This gating system design enables sequential solidification and smooth filling of the molten metal during the casting process, allowing the molten metal to flow smoothly within the feeding channel, increasing the temperature around the insert ring, and improving the piston quality.

[0058] By setting the above, the flow rate of the molten alloy 8 in the first ingate 521, the second ingate 522 and the third ingate 523 can be gradually slowed down, so that the molten alloy 8 enters the mold cavity more smoothly, reducing the casting speed and avoiding splashing when the molten alloy 8 enters the mold cavity. Turbulence on the surface of the molten alloy 8 will weaken the quality of the casting.

[0059] In some embodiments, an outer mold positioning ring 13 is provided at a preset position on the first outer mold 11 and the second outer mold 12. A positioning part is provided on the outer mold positioning ring 13 at a position corresponding to the limiting cavity. The limiting part 21 of the insert ring 2 can pass through the positioning part and be installed into the limiting cavity. Specifically, the outer mold positioning ring 13 can be directly machined on the first outer mold 11 and the second outer mold 12. The outer mold positioning ring 13 corresponds to the installation position of the insert ring 2 and has a similar shape. The limiting cavity corresponds to the position of the positioning part on the outer mold positioning ring 13, which facilitates the installation of the limiting part 21. After the insert ring 2 is installed, it is suspended in the middle of the outer mold positioning ring 13. The setting of the outer mold positioning ring 13 can facilitate the positioning and installation of the insert ring 2. By aligning the position of the limiting part 21 of the insert ring 2 with the positioning part of the outer mold positioning ring 13, the limiting part 21 of the insert ring 2 can be quickly assembled into the limiting cavity.

[0060] In some implementations, such as Figure 4 and Figure 5As shown, it also includes an air supply component 6. The first outer mold 11 and / or the second outer mold 12 are provided with a first air supply channel 61. One end of the first air supply channel 61 is connected to the air supply component 6, and the other end is connected to the limiting cavity, so that the gas in the air supply component 6 passes through the first air supply channel 61 and blows towards the limiting cavity, thereby blowing out the residue in the limiting cavity. Specifically, the first air supply channel 61 is provided on the first outer mold 11 and / or the second outer mold 12, preferably on both the first outer mold 11 and the second outer mold 12. The first air supply channel 61 can be located on both sides of the limiting cavity. An inlet / outlet pipe connector 63 is also provided on the side of the first outer mold 11 and the second outer mold 12. One end of the inlet / outlet pipe connector 63 is inserted into the first air supply channel 61. A gasket is provided between the inlet / outlet pipe connector 63 and the first air supply channel 61. An annular step is provided on the inlet / outlet pipe connector 63. One end of the annular step is engaged with the edge of the first air supply channel 61. A hose connector, i.e., an air pipe, is also provided on the side of the inlet / outlet pipe connector 63 away from the first air supply channel 61. The first air supply channel 61 is provided on both the left and right sides of the first outer mold 11 and the second outer mold 12 to ensure the uniformity of airflow.

[0061] In some embodiments, the fixing component 3 is further provided with a second air supply channel 62. One end of the second air supply channel 62 is connected to the first air supply channel 61, and the other end is connected to the mold cavity. Specifically, the second air supply channel 62 is provided on the positioning push rod 31. The positioning push rod 31 has a hollow part in the middle, which is connected to the first air supply channel 61. Several second air supply channels 62 are provided near the insert ring 2 on the positioning push rod 31. One end of the second air supply channel 62 is connected to the hollow part, and the other end is open near the insert ring 2. The airflow enters the first air supply channel 61 through the ventilation pipe, and then enters the second air supply channel 62 through the hollow part of the positioning push rod 31. High-speed gas enters through the ventilation pipe, blowing away aluminum chips or slag, keeping the outer mold positioning ring 13 clean, and not affecting the positioning of the insert ring 2 next time.

[0062] In addition to the piston casting molds mentioned above, such as Figures 6-1 to 6-6 As shown, the present invention also provides a piston casting method.

[0063] The piston casting method includes the following steps:

[0064] Turn on the casting machine and heat the molten alloy for casting and the molten alloy for infiltrating the ring to the preset temperature, then transfer them to the casting station; the molten alloy for casting is the molten alloy used to cast the piston, and the molten alloy for infiltrating the ring refers to the molten alloy used to heat the ring 2 before it is assembled into the mold.

[0065] The first outer mold 11 and the second outer mold 12 in the control piston casting mold automatically close, leaving a gap, and the heating component 4 is activated;

[0066] Obtain the insert ring 2 and place the insert ring limiting part 21 of the insert ring 2 into the limiting cavity of the first outer mold 11 and the second outer mold 12;

[0067] The first outer mold 11 and the second outer mold 12 are automatically closed until the inlaid ring limiting part 21 abuts against the fixing component 3;

[0068] The piston casting mold is tilted at an angle of B1 relative to the horizontal direction to cast the first area of ​​the mold cavity; the tilt angle of the piston casting mold is adjusted to B2 to cast the second area of ​​the mold cavity; the tilt angle of the piston casting mold is adjusted to B3 to cast the third area of ​​the mold cavity; the first, second, and third areas are arranged from bottom to top; the tilt angle of the piston casting mold is slowly adjusted to B4 while continuing to pour until the sprue 51 is full, and the piston casting mold is slowly lowered to a flat position to complete the pouring; the tilt angles B1, B2, B3, and B4 decrease sequentially.

[0069] Control the opening of the first outer mold 11 and the second outer mold 12 to remove the piston blank.

[0070] Specifically, the tilting of the casting machine causes the piston casting mold to tilt, which effectively improves the flowability of the molten alloy 8 and avoids backflow of the molten aluminum at blockage points. That is, the piston casting method provided by this invention, by changing the casting method, utilizes the casting machine to tilt the piston casting mold, and during the casting process, the tilt angle gradually decreases, meaning the piston casting mold gradually approaches horizontality from tilted. This effectively improves the fluidity of the molten alloy 8, avoids backflow of the molten alloy 8 at blockage points, prevents turbulence and backflow of the molten alloy 8, and eliminates casting defects such as shrinkage porosity and shrinkage cavities on the upper surface of the sprue 51.

[0071] In some embodiments, the tilt angles B1, B2, B3, and B4 are 30-38°, 28-35°, 20-25°, and 10-15°, respectively. That is, the casting process includes: controlling the tilt angle of the piston casting mold to 30-38° to cast the first region of the mold cavity; controlling the tilt angle of the piston casting mold to 28-35° to cast the second region of the mold cavity; controlling the tilt angle of the piston casting mold to 20-25° to cast the third region of the mold cavity; the first, second, and third regions are arranged from bottom to top; the piston casting mold is slowly adjusted to a tilt angle of 10-15° while continuing to pour until the sprue 51 is full; the piston casting mold is then slowly leveled, and the casting is completed.

[0072] In some embodiments, the steps of starting the casting machine and heating the molten alloy for casting and the molten alloy for inlaying rings to a preset temperature, and then transferring them to the casting station, include:

[0073] The main power supply of the casting machine, start-up equipment, chiller, air compressor and air dryer, set the cooling water temperature of the piston casting mold to 20-30℃, and the cooling water pressure of the piston casting mold to 1.3-1.5MPa to ensure normal operation.

[0074] The refined and degassed molten alloy for casting and the molten alloy for infiltrating the ring are transferred to the casting station. The molten alloy for casting is kept at 740-760°C, and the molten alloy for infiltrating the ring is kept at 710-730°C. By controlling the cooling water temperature and pressure of the piston casting mold, as well as the temperatures of the molten alloy for casting and the molten alloy for infiltrating the ring, it can be ensured that the temperature of the ring 2 is close to that of the molten alloy 8 after it is installed in the outer mold 1, thus avoiding a large temperature difference.

[0075] In one specific embodiment, the piston casting mold and piston casting method provided by the present invention mainly include the following process steps:

[0076] 1. Turn on the main power of the casting machine, start the equipment, chiller, air compressor and air dryer, set the mold cooling water temperature to 20-30℃, the air pressure of the insert ring 2 clamps to 0.20-0.5MPa, and the mold cooling water pressure to 1.3-1.5MPa;

[0077] 2. Transfer the refined and degassed alloy liquid 8 and the ring-infiltrating alloy liquid to the casting station. The alloy liquid for casting is kept at a temperature of 740-760℃, and the temperature of the ring-infiltrating alloy liquid is 710-730℃.

[0078] 3. When the first outer mold 11 and the second outer mold 12 of the casting mold automatically close, leaving a gap of 5-10mm; at the same time, the heating coil 41 of the first outer mold 11 and the second outer mold 12 is activated to store heat, increase the temperature of the outer mold positioning ring 13 and the surrounding area, increase the temperature of the contact surface of the insert 2, and reduce the temperature difference between the insert 2 and the outer mold positioning ring 13.

[0079] 4. The lower ring robot automatically picks up the inlay rings 2 one by one from the aluminizing hook, and then places the inlay rings 2 in the center on the horizontal plane aligned with the outer mold positioning ring sleeve 13. The inlay ring limiting part 21 is placed correspondingly to the outer mold positioning ring sleeve 13.

[0080] 5. The first outer mold 11 and the second outer mold 12 slowly and automatically close. The insert ring limiting part 21 is nested in the positioning ejector rod 31. The draft angle of the insert ring limiting part 21 is 10° to 15°. The elastic component 32 in the first outer mold 11 and the second outer mold 12 is in a slow compression state. At the same time, the elastic component 32 is forced to press against the positioning ejector rod 31, so that the positioning ejector rod 31 and the two ends of the insert ring 2 are in a state of force. At this time, the lower ring robot arm retracts. At this time, the positioning of the insert ring 2 is completed. The time from when the insert ring 2 leaves the aluminizing furnace to when the working alloy is poured to cover the lower ring of the insert ring 2 must be ≤30 seconds.

[0081] 6. Close the mold cover of the casting machine 7, tilt the casting mold 30°~38° to prepare for casting, and wait for the alloy liquid to be poured 8;

[0082] 7. Press the pouring button, and the robot will automatically pour the alloy liquid 8. When the alloy liquid 8 mainly flows into the mold from the area of ​​the first inner gate 521, the pouring mold is slowly lowered to a flat angle of 28° to 35°. When the alloy liquid 8 mainly flows into the mold from the area of ​​the second inner gate 522, the pouring mold is slowly lowered to a flat angle of 20° to 25°. The liquid flow must be stable and continuous without interruption. Depending on the piston cylinder diameter, the pouring time from the start of pouring to the completion of pouring is 200s to 300s. The pouring time should be shortened as much as possible so that the alloy liquid 8 fills the gate 5 and approaches the pouring cup 53 of the mold.

[0083] 8. When most of the molten alloy 8 in the ladle has been poured, and the molten alloy 8 in the cavity has covered the lower end face of the insert ring 2, the casting mold is slowly lowered to a flat angle of 10° to 15°, while the pouring action is not stopped until the riser is full. The casting mold is then slowly lowered to a flat angle, and the pouring is completed. The area ratio of the ingate 52 is S1:S2:S3 = 1:0.8 to 0.6:0.5 to 0.3. S1, S2, and S3 represent the cross-sectional areas of the first ingate 521, the second ingate 522, and the third ingate 523 at the junction with the mold cavity, respectively.

[0084] 9. After the piston casting is poured, the heating coil 41 of the insert ring 2 stops heating, the mold cover 7 rises first, the first outer mold 11 and the second outer mold 12 slowly move backwards, the two protruding positioning ends of the insert ring 2 disengage from the outer mold positioning ring 13, and high-speed gas enters through the ventilation pipe to blow away aluminum chips or slag, keeping the outer mold positioning ring 13 clean and not affecting the positioning of the insert ring 2 next time.

[0085] 10. The formed piston blank should be removed within 5 seconds and clamped into the air-cooling rack or water tank for air cooling or water quenching as required.

[0086] Regarding the structural design of the gating system 5, several specific embodiments are given, as shown in Table 1.

[0087] Table 1. Sprue structure design for pistons with different cylinder diameters (unit: mm)

[0088]

[0089] Among them, such as Figure 2 As shown, H = P + E + D / 2; D = Q / 6; E = 20 + D; P = Q + D; the unit is mm.

[0090] The piston casting mold and piston casting method have the following beneficial effects:

[0091] 1. The design of the sprue 5 and the pouring method of the alloy liquid 8 are different: a three-section sprue 51 is adopted, the draft angle of the three-section sprue 51 is 30°~35°, and the pouring mold is inclined in three sections to avoid defects such as shrinkage caused by turbulence of the alloy liquid 8 in the upper sprue 51.

[0092] 2. The structural design of the first inner gate 521, the second inner gate 522 and the third inner gate 523, along with the inclined gate 5 design, changes the filling direction, speed and flow rate of the alloy liquid 8, thereby reducing the filling speed of the alloy liquid 8. This is suitable for the mold structure of the outer mold 1, which requires stable filling, and defects such as gate shrinkage are significantly improved.

[0093] 3. Design of the inlaid ring 2 structure, outer mold 1 structure and positioning method of inlaid ring 2: Unlike the previous inlaid ring 2 structure and positioning method, an inlay positioning method is adopted, which improves the positioning accuracy of inlaid ring 2, provides conditions for the optimization of the sprue 5 structure, and improves the reliability and service life of piston.

[0094] The piston casting mold and piston casting method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the piston casting method and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A piston casting mold, characterized in that, include: The first outer mold (11) and the second outer mold (12) are set separately. A mold cavity is provided between the first outer mold (11) and the second outer mold (12). A limiting cavity is provided on the first outer mold (11) and the second outer mold (12) near the mold cavity. The limiting part (21) of the ring (2) around the ring is detachably installed in the limiting cavity so that the ring (2) is suspended in the mold cavity. The fixing component (3) is installed in the limiting cavity to fix the insert limiting part (21). Heating component (4), mounted on the first outer mold (11) and / or the second outer mold (12), is used to heat the insert (2). The fixing component (3) includes an elastic component (32) and a positioning push rod (31). One end of the positioning push rod (31) abuts against the elastic component (32), and the other end abuts against the insert ring limiting part (21). It also includes an air supply component (6). The first outer mold (11) and / or the second outer mold (12) are provided with a first air supply channel (61). One end of the first air supply channel (61) is connected to the air supply component (6), and the other end is connected to the limiting cavity. The fixing component (3) is also provided with a second air supply channel (62). One end of the second air supply channel (62) is connected to the first air supply channel (61), and the other end is connected to the mold cavity. The second air supply channel (62) is provided on the positioning push rod (31). A sprue (5) is provided between the first outer mold (11) and the second outer mold (12). The sprue (5) is provided with a sprue (51) and a plurality of insprues (52) connected to the sprue (51). The side of the insprues (52) away from the sprue (51) is connected to the mold cavity respectively. Each insprue (52) is inclined downward from the side of the mold cavity closest to the sprue (51).

2. The piston casting mold according to claim 1, characterized in that, The opening of the limiting cavity is provided with a stepped surface, and the positioning rod (31) is provided with a stepped portion. The stepped portion of the positioning rod (31) is engaged with the stepped surface to prevent the positioning rod (31) from disengaging from the limiting cavity. The heating assembly (4) includes a heating coil (41), which is wrapped around the stepped portion of the positioning rod (31).

3. The piston casting mold according to claim 1, characterized in that, The draft angle of the ingate (52) relative to the horizontal direction is 30-35°.

4. The piston casting mold according to claim 3, characterized in that, The ingate (52) includes a first ingate (521), a second ingate (522), and a third ingate (523). The area ratio of the cross-sectional area of ​​the first ingate (521), the second ingate (522), and the third ingate (523) at the interface with the mold cavity is S1:S2:S3=1:0.8~0.6:0.5~0.3; and the ingate structure design adopts the following formula: H=P+E+D / 2; D=Q / 6; E=20+D; P=Q+D; Wherein: H refers to the distance between the inner wall of the pouring cup (53) away from the mold cavity and the mold cavity axis; P refers to the distance between the outer wall of the pouring cup (53) close to the mold cavity and the mold cavity axis; E refers to the diameter of the pouring cup (53); D refers to the distance between the bottom of the first inner sprue (521) and the upper surface of the insert (2); Q refers to the piston cylinder diameter, Q=85-200mm.

5. The piston casting mold according to claim 1, characterized in that, The first outer mold (11) and the second outer mold (12) are provided with an outer mold positioning ring (13) at a preset position. The outer mold positioning ring (13) is provided with a positioning part at a position corresponding to the limiting cavity. The inlay ring (2) of the inlay ring (2) passes through the positioning part and is inserted into the limiting cavity.

6. A piston casting method, employing a piston casting mold as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Turn on the casting machine and heat the alloy liquid (8) for casting to the preset temperature, then transfer it to the casting station; The first outer mold (11) and the second outer mold (12) in the piston casting mold are controlled to automatically close, leaving a gap, and the heating assembly (4) is started. Obtain the insert ring (2) and place the insert ring limiting part (21) of the insert ring (2) into the limiting cavity of the first outer mold (11) and the second outer mold (12); Control the first outer mold (11) and the second outer mold (12) to automatically close the mold until the inlaid ring limiting part (21) abuts against the fixing component (3); The piston casting mold is tilted at an angle of B1 relative to the horizontal direction to cast the first region of the mold cavity; the piston casting mold is tilted at an angle of B2 relative to the horizontal direction to cast the second region of the mold cavity; the piston casting mold is tilted at an angle of B3 relative to the horizontal direction to cast the third region of the mold cavity; the first region, the second region, and the third region are arranged from bottom to top; the piston casting mold is slowly tilted at an angle of B4 relative to the horizontal direction while continuing to cast until the sprue (51) is full, and the piston casting mold is slowly leveled to complete the casting; wherein the tilt angles B1, B2, B3, and B4 decrease sequentially; the tilt angles B1, B2, B3, and B4 are 30-38°, 28-35°, 20-25°, and 10-15°, respectively; Control the opening of the first outer mold (11) and the second outer mold (12) to remove the piston blank.

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