Low thermal stress glass mold and method of making the same

Abstract

A low-thermal-stress glass mold and its preparation method are disclosed, belonging to the field of glass mold technology. The mold includes a bottle half-mold used in pairs, facing each other towards one side of a pair of mold-fitting surfaces. The bottle half-mold has a cavity, characterized by: within the wall thickness of the bottle half-mold, axially arranged, independent yet spaced apart, each penetrating from one side of the pair of mold-fitting surfaces to the other, comprising a lower built-in annular cavity, a middle built-in annular cavity, and a neck / shoulder built-in annular cavity. The openings of the lower, middle, and neck / shoulder built-in annular cavities are closed at the points where they meet the mold-fitting surfaces. Advantages: Without changing the inner wall dimensions and cooling boundary conditions, it solves the problem of high thermal stress caused by large radial temperature gradients in solid glass molds, extending service life; the method has controllable manufacturing costs, feasible processes, and ensures a significant reduction in thermal stress in the prepared glass mold.

Description

Technical Field

[0001] This invention belongs to the field of glass mold technology, specifically relating to a low thermal stress glass mold, and also to its preparation method. Background Technology

[0002] Glass molds are equipment used to manufacture glass products. Different types of glass products require different molds, such as blow-blow molds, press-blow molds, compression molding molds, centrifugal forming molds, and so on. For small-mouthed bottles such as wine bottles, beer bottles, and infusion bottles, blow-blow molding is typically used.

[0003] The glass molds used in the aforementioned blow-blow molding of glass containers are matched with row-type bottle-making machines. During operation, the inner wall of the glass mold, i.e., the mold cavity (also called the "container"), is in direct contact with the high-temperature molten glass at 700°C to 1100°C, while the outer wall is usually cooled by forced air (approximately 40°C). This results in a huge temperature gradient of up to 200°C along the thickness direction of the mold wall. The resulting thermal stress is the main reason for thermal fatigue cracks on the inner wall of the mold, ultimately leading to its failure and scrapping.

[0004] To reduce thermal stress and extend the service life of glass molds, existing technologies typically employ the following measures: First, optimizing the cooling process, such as adjusting the cooling intensity of the outer wall or the cooling sequence of the inner wall. However, due to limitations in glass forming processes, the adjustment space is limited. Second, nickel-based alloy inserts are placed within the cavity, a typical example being CN106966569A (an alloy mold with a cast nickel core and its preparation method). However, compared to ordinary vermicular graphite cast iron molds, the cost is 5-10 times higher, and it is still a solid structure, so the thermal stress problem is not fundamentally solved. Third, coatings or grooves are applied to the outer wall, but the effect does not meet expectations, i.e., it is difficult to significantly reduce the temperature gradient. Fourth, axial cooling holes and venting holes are opened, a typical example being CN104163560A (a mold for making bottle-type glass containers). However, the structure is complex, and the processing technology is relatively complicated.

[0005] Therefore, it is of great significance to explore glass molds that can significantly reduce thermal stress, keep costs under control, and have feasible processes without changing the inner wall size and cooling boundary conditions. The technical solution to be introduced below was developed in this context. Summary of the Invention

[0006] The objective of this invention is to provide a low thermal stress glass mold that helps to extend the service life of solid glass molds by solving the problem of high thermal stress caused by large radial temperature gradients without changing the inner wall dimensions and cooling boundary conditions.

[0007] Another objective of this invention is to provide a method for preparing a low-thermal-stress glass mold, which has controllable preparation costs, feasible processes, and can ensure that the thermal stress of the prepared glass mold is significantly reduced.

[0008] The objective of this invention is achieved by providing a low-thermal-stress glass mold comprising a bottle half mold used in pairs, which are positioned opposite each other on one side of a pair of mold-fitting surfaces. The bottle half mold has a bottle half mold cavity, characterized in that: within the wall thickness of the bottle half mold, along its axial direction, are provided three independent and spaced-apart annular cavities, each penetrating from one side of the pair of mold-fitting surfaces to the other side. The openings of the lower, middle, and neck / shoulder annular cavities are closed at the locations of the pair of mold-fitting surfaces.

[0009] In a specific embodiment of the present invention, the wall thickness of the bottle half mold in the region corresponding to the lower built-in annular cavity is configured as the lower wall thickness of the bottle half mold, the wall thickness in the region corresponding to the middle built-in annular cavity is configured as the middle wall thickness of the bottle half mold, and the wall thickness in the region corresponding to the neck and shoulder built-in annular cavity is configured as the neck and shoulder wall thickness of the bottle half mold.

[0010] In another specific embodiment of the present invention, the thickness of the lower wall of the bottle half mold is less than the thickness of the middle wall of the bottle half mold, and the thickness of the middle wall of the bottle half mold is less than the thickness of the neck and shoulder wall of the bottle half mold.

[0011] In another specific embodiment of the present invention, the cross-sectional shape of the lower built-in annular cavity, the middle built-in annular cavity, and the neck and shoulder built-in annular cavity is circular, and the radial distance between the inner wall of the lower built-in annular cavity, the inner wall of the middle built-in annular cavity, and the inner wall of the neck and shoulder built-in annular cavity and the inner wall of the bottle half mold cavity of the bottle half mold is the same, and the radial distance is 5-8mm.

[0012] In another specific embodiment of the present invention, the radii of the lower built-in annular cavity, the middle built-in annular cavity, and the neck and shoulder built-in annular cavity are the same.

[0013] In another specific embodiment of the present invention, the ratio of the distance between the center of the lower built-in annular cavity and the bottom surface of the bottle half mold to the height of the bottle half mold is 1:6.9, the ratio of the distance between the center of the middle built-in annular cavity and the bottom surface of the bottle half mold to the height of the bottle half mold is 1:2.30167, and the ratio of the distance between the center of the neck and shoulder built-in annular cavity and the bottom surface of the bottle half mold to the height of the bottle half mold is 1:2.008.

[0014] In a further specific embodiment of the present invention, the distance between the bottom surface and the top surface of the bottle half mold is 276.2 mm, the distance between the center of the lower built-in annular cavity and the bottom surface of the bottle half mold is 40 mm, the distance between the center of the middle built-in annular cavity and the bottom surface of the bottle half mold is 120 mm, and the distance between the center of the neck and shoulder built-in annular cavity and the bottom surface of the bottle half mold is 230 mm.

[0015] In a further specific embodiment of the present invention, the distance between the center of the lower built-in annular cavity and the central axis of the bottle half mold cavity is 49.55 mm, the distance between the center of the middle built-in annular cavity and the central axis of the bottle half mold cavity is 47.59 mm, and the distance between the center of the neck and shoulder built-in annular cavity and the central axis of the bottle half mold cavity is 29.96 mm.

[0016] Another objective of this invention is achieved by providing a method for preparing a low-thermal-stress glass mold, comprising the following steps: A) Prepare a half-mold casting of a soluble salt core bottle to be installed. In the wall thickness of the half-mold casting, a lower salt core mounting hole, a middle salt core mounting hole, and a neck and shoulder salt core mounting hole are reserved along its axial direction. The lower salt core mounting hole, the middle salt core mounting hole, and the neck and shoulder salt core mounting hole are each made to penetrate from one side of the joint surface of a pair of casting bodies to the other side of the joint surface of a pair of casting bodies, thus obtaining the half-mold casting of the soluble salt core bottle to be installed. B). Prepare a soluble salt core bottle half-mold casting body, embed the pre-made soluble salt core into the lower salt core mounting hole, the middle salt core mounting hole and the neck and shoulder salt core mounting hole respectively, and make the two ends of the soluble salt core protrude out of the opening of the mounting hole and insert into the positioning groove on the parting surface of the corresponding bottle half-mold casting body to obtain a bottle half-mold casting body with soluble salt core installed; C) Casting: Molten metal is poured into a sand mold in the closed state, cooled, solidified, and removed from the mold to obtain a bottle half mold with a pair of mold surfaces and forming a bottle half mold cavity; D) Dissolving the salt core: The soluble salt core described in step B) is dissolved and emptied using a 40-60℃ warm water dissolution method, immersion dissolution method, pressure spraying method, or ultrasonic-assisted dissolution method. After subsequent processing, including heat treatment, a low-thermal-stress glass mold is obtained, which has a lower built-in annular cavity, a middle built-in annular cavity, and a neck and shoulder built-in annular cavity, and the opening of the annular cavity is closed at the parting surface of a pair of molds.

[0017] In yet another specific embodiment of the present invention, the soluble salt core mentioned in steps B) and D) is a water-soluble chloride, which is a sodium chloride-based soluble salt.

[0018] The technical effect of the solution provided by this invention is as follows: Because the lower, middle, and neck / shoulder annular cavities are independently and interspersed with each other along the axial direction within the wall thickness of the bottle half-mold, and each extends from one side of a pair of mold-fitting surfaces to the other, the thermal stress is significantly reduced. Using Abaqus finite element software for thermo-mechanical coupling analysis, under the same material parameters and thermal boundary conditions (forming stage: inner wall contact glass temperature 1100℃→700℃ (5.5 seconds), forced convection cooling of the outer wall; cooling stage: natural convection of the inner wall): the maximum Mises thermal stress of the solid mold is 176.3 MPa; the maximum Mises thermal stress of the mold of this invention is 104.5 MPa, a reduction of 40.72%.

[0019] Significantly extended mold life: Thermal stress is the root cause of thermal fatigue cracks on the inner wall of the mold. Reducing thermal stress can directly delay crack initiation and propagation. It is estimated that the mold life of this invention can be extended by 2 to 3 times, greatly reducing the frequency of mold replacement and production costs.

[0020] Without sacrificing glass forming quality: Simulations show that the highest temperature rise on the inner wall is approximately 78.5℃. This temperature rise originates from the cavity's blocking effect on radial heat flow, meaning the heat is effectively controlled near the inner wall of the mold. This is the physical mechanism by which the cavity can significantly reduce the temperature difference between the inner and outer walls, thereby reducing thermal stress. It should be noted that the mold's highest operating temperature is still far below the phase transformation temperature (approximately 1150℃) and the temperature of most severe oxidation (above approximately 850℃) of cast iron, and will not damage the mold material's properties. Simultaneously, at this temperature, the glass cooling rate remains within the process window (the cooling curve of glass from 1100℃ to 700℃ remains essentially unchanged), and the radial deformation difference does not exceed 0.087mm, not affecting the dimensional accuracy and surface quality of the finished product.

[0021] Manufacturing costs are controllable: the three cavities use standardized soluble salt cores with a uniform radius, requiring only one set of core molds; the casting process is simple, and the cost is only about 10% to 15% higher than that of solid molds, which is far lower than that of nickel-based alloy inserts and other solutions.

[0022] Easy maintenance: The cavity opening is completely sealed, eliminating the risk of leakage; the mold body is a single piece with no assembly gaps, ensuring a reliable structure. Attached Figure Description

[0023] Figure 1 The diagram shows the structure of a glass mold used to make beer bottles. Figure 2 for Figure 1 A schematic diagram showing the front and side views of the bottle half mold cavity; Figure 3 This is a schematic diagram of the temperature distribution of the glass mold obtained in Embodiment 1 of the present invention at the end of the glass container forming stage. Figure 4 This is a schematic diagram of the stress distribution of the glass mold obtained in Embodiment 1 of the present invention at the end of the glass container forming stage; Figure 5 This is a schematic diagram of the temperature distribution of the glass mold obtained in Embodiment 2 of the present invention at the end of the glass container forming stage. Figure 6 This is a schematic diagram of the stress distribution of the glass mold obtained in Embodiment 2 of the present invention at the end of the glass container forming stage; Figure 7 This is a schematic diagram of the temperature distribution of the glass mold obtained in Embodiment 3 of the present invention at the end of the glass container forming stage. Figure 8 This is a schematic diagram of the stress distribution of the glass mold obtained in Embodiment 3 of the present invention at the end of the glass container forming stage; Figure 9 This is a schematic diagram of the temperature distribution of a glass mold at the end of the glass container forming stage in an existing technology. Figure 10 This is a schematic diagram of the stress distribution of a glass mold at the end of the glass container forming stage in the prior art.

[0024] In the diagram: 1. Bottle half mold, 11. Mold parting surface, 12. Bottle half mold cavity, 13. Lower internal annular cavity, 14. Middle internal annular cavity, 15. Neck and shoulder internal annular cavity, 16a. Lower wall thickness of bottle half mold, 16b. Middle wall thickness of bottle half mold, 16c. Neck and shoulder wall thickness of bottle half mold, 17a. Bottom surface of bottle half mold, 17b. Top surface of bottle half mold; L. Radial distance. Detailed Implementation

[0025] Example 1: The mold geometry parameters are as follows: Symmetry axis: Y-axis (axial height), X-axis is the radial radius.

[0026] Inner wall profile (X, Y) (as per user requirements, unit: mm); Bottom point: (36.55, 0); straight up to (33.5, 186.2); curve to (18.787, 212.9); curve to (12.0, 276.2); Outer wall: Vertical line X=76, Y from 0 to 276.2; Total height: 276.2mm; Bottom wall thickness: 39.45 mm; middle wall thickness: approximately 42.5 mm; shoulder wall thickness: approximately 64 mm.

[0027] Cavity parameters: In this invention, the center positions (radial coordinate X and axial coordinate Y) of the three annular cavities are not arbitrarily selected, but are obtained through finite element simulation based on the following principles: (1) Axial position (Y coordinate): corresponding to the three peak areas that appear in the thermal stress analysis of the solid mold: bottom area (Y≈20~60mm), middle area of ​​bottle body (Y≈100~150mm, with the highest heat flux density), and shoulder transition area (Y≈200~250mm, with large curvature changes). Placing the cavity center at the center of each peak area (Y=40, 120, 230mm) can maximize the thermal insulation effect of the cavity to cover the high stress area.

[0028] (2) Radial position (X coordinate): To ensure that the cavity can effectively block heat flow without weakening the strength of the mold structure, the radial distance between the inner wall of the cavity and the inner wall of the mold is set to 5 mm (approximately equal to the minimum safe wall thickness of cast iron). Therefore, the radius of the cavity center = the inner wall radius at the Y coordinate + 5 mm + the cavity radius (8 mm). The specific calculation method is shown in the table below.

[0029] (3) Cavity radius: 8mm is the optimal value after taking into account the thinnest bottom wall thickness (39.45mm) and the standardized core radius. Under this radius, the remaining thickness of the outer wall is greater than 14mm, ensuring that the strength requirements are met.

[0030] The choice of three cavities was based on the following considerations: fewer than three cavities would not cover the three peak thermal stress areas at the bottom, middle, and shoulder; more than three cavities would result in diminishing marginal benefits and excessively weaken the overall rigidity of the mold, increasing casting difficulty. Simulation verification showed that three cavities represent the optimal balance between stress reduction and structural integrity.

[0031]

[0032] Please see Figure 1 and Figure 2 According to the above parameters, Figure 1 and Figure 2 The method for preparing the low thermal stress glass mold with the structure shown includes the following steps: A) Prepare a half-mold casting of a soluble salt core bottle to be installed. In the wall thickness of the half-mold casting, a lower salt core mounting hole, a middle salt core mounting hole, and a neck and shoulder salt core mounting hole are reserved along its axial direction. The lower salt core mounting hole, the middle salt core mounting hole, and the neck and shoulder salt core mounting hole are each made to penetrate from one side of the joint surface of a pair of casting bodies to the other side of the joint surface of a pair of casting bodies, thus obtaining the half-mold casting of the soluble salt core bottle to be installed. B). Prepare a soluble salt core bottle half-mold casting body, embed the pre-made soluble salt core into the lower salt core mounting hole, the middle salt core mounting hole and the neck and shoulder salt core mounting hole respectively, and make the two ends of the soluble salt core protrude out of the opening of the mounting hole and insert into the positioning groove on the parting surface of the corresponding bottle half-mold casting body to obtain a bottle half-mold casting body with soluble salt core installed; C). Casting: Molten metal is poured into a sand mold in the closed state, cooled, solidified, and removed from the mold to obtain a bottle half mold 1 with a pair of mold surfaces 11 and forming a bottle half mold cavity 12. D) Dissolving the salt core: The soluble salt core described in step B) is dissolved and emptied using a 40-60℃ warm water dissolution method, immersion dissolution method, pressure spraying method, or ultrasonic-assisted dissolution method. After subsequent processing including heat treatment, a low-thermal-stress glass mold is obtained, which has a lower built-in annular cavity 13, a middle built-in annular cavity 14, and a neck and shoulder built-in annular cavity 15, and the opening of the annular cavity is closed at the parting surfaces 11.

[0033] The soluble salt core described in steps B) and D) above is a water-soluble chloride, specifically a sodium chloride-based soluble salt (a small amount of binder may be added). It is pressed into shape in a specialized mold. The salt core is cylindrical, 16 mm in diameter, with a protruding end at the center of each end, 5 mm in diameter and 5 mm in length. After pressing, it is dried and cured.

[0034] The lower annular cavity 13, the middle annular cavity 14, and the neck and shoulder annular cavity 15, i.e., the coordinates of the center of these three cavities (X=49.55, Y=40; X=47.59, Y=120; X=29.96, Y=230), are used to machine positioning grooves (counterholes) with a diameter of 5 mm and a depth of 5 mm.

[0035] In this embodiment, the wall thickness of the bottle half mold 1 in the region corresponding to the lower built-in annular cavity 13 is configured as the lower wall thickness 16a, the wall thickness in the region corresponding to the middle built-in annular cavity 14 is configured as the middle wall thickness 16b, and the wall thickness in the region corresponding to the neck and shoulder built-in annular cavity 15 is configured as the neck and shoulder wall thickness 16c. The thickness of the lower wall thickness 16a is less than the thickness of the middle wall thickness 16b, and the thickness of the middle wall thickness 16b is less than the thickness of the neck and shoulder wall thickness 16c. The cross-sectional shape of the lower built-in annular cavity 13, the middle built-in annular cavity 14, and the neck and shoulder built-in annular cavity 15 is circular. The radial distance L between the inner wall of the lower built-in annular cavity 13, the inner wall of the middle built-in annular cavity 14, and the inner wall of the neck and shoulder built-in annular cavity 15 and the inner wall of the bottle half mold cavity 12 of the bottle half mold 1 is the same, for example, 5-8 mm each. The radii of the three built-in annular cavities are also the same, for example, 8 mm each.

[0036] The ratio of the distance between the center of the lower built-in annular cavity 13 and the bottom surface 17a of the bottle half mold 1 to the height of the bottle half mold 1 is 1:6.9; the ratio of the distance between the center of the middle built-in annular cavity 14 and the bottom surface 17a of the bottle half mold to the height of the bottle half mold 1 is 1:2.30167; and the ratio of the distance between the center of the neck and shoulder built-in annular cavity 15 and the bottom surface 17a of the bottle half mold to the height of the bottle half mold 1 is 1:2.008.

[0037] The distance from the bottom surface 17a of the aforementioned bottle half mold to the top surface 17b of the bottle half mold is 276.2 mm. According to the parameters in the table above, the distance from the center of the lower built-in annular cavity 13 to the bottom surface 17a of the bottle half mold 1 is 40 mm; the distance from the center of the middle built-in annular cavity 14 to the bottom surface 17a of the bottle half mold 1 is 120 mm; and the distance from the center of the neck and shoulder built-in annular cavity 15 to the bottom surface 17a of the bottle half mold 1 is 230 mm. Also as shown in the table above, the distance from the center of the lower built-in annular cavity 13 to the central axis Y of the bottle half mold cavity 12 is 49.55 mm; the distance from the center of the middle built-in annular cavity 14 to the central axis Y of the bottle half mold cavity 12 is 47.59 mm; and the distance from the center of the neck and shoulder built-in annular cavity 15 to the central axis Y of the bottle half mold cavity 12 is 29.96 mm.

[0038] For core fixing and pouring, insert the protruding ends of the three salt cores into their corresponding positioning slots to ensure that the salt core bodies are positioned in the predetermined positions within the mold cavity. After closing the mold, pour in molten cast iron (such as HT250) at a temperature of approximately 1350℃.

[0039] Regarding core removal and cleaning, after the casting has cooled, it is opened from the mold and rinsed or soaked with water to dissolve the salt core, forming a closed annular cavity. The parting surface is then cleaned, and the gating and riser are removed.

[0040] As for subsequent processing or finishing, the inner wall (to ensure the dimensions specified by the customer), parting surface, positioning pin holes, etc. are finished to complete the semi-finished product.

[0041] The result obtained in Example 1 is... Figure 1 and Figure 2 Simulation verification of the bottle half-mold 1 shown: Please see Figure 3 and Figure 4 The finite element model used in this invention is constructed based on engineering drawings of actual glass molds. To balance computational efficiency and accuracy, some details of the real mold have been reasonably simplified: features with minimal impact on heat conduction and thermal stress distribution, such as the minute chamfers of the mold parting surface, mold closing positioning pin holes, and external wall heat dissipation fins, have been omitted; the three-dimensional mold has been simplified into a two-dimensional axisymmetric model, utilizing the rotational symmetry of the mold to significantly reduce computational costs while ensuring the accuracy of calculations for radial and axial temperature gradients and stress distribution. The simplified geometric contours (coordinates of key points on the inner wall, radius of the outer wall, and total height) are completely consistent with the real mold. All simulation conclusions are based on this simplified model and do not affect the judgment of the significant technical effects of this invention.

[0042] (1) Software: Abaqus 6.14.2; (2) Model: Two-dimensional axisymmetric model; (3) Element type: DCAX4, DCAX3 (axisymmetric quadrilateral, triangular heat conduction element); CAX4, CAX3 (axisymmetric quadrilateral, triangular stress / displacement element); (4) Material parameters (cast iron): elastic modulus 170 GPa, Poisson's ratio 0.29, thermal conductivity 34 W / (m·K), specific heat 480 J / (kg·K), density 7200 kg / m³, coefficient of thermal expansion 1.2×10 -5 / K; (5) Boundary conditions (thermodynamic analysis): Initial temperature: 600℃ (mold preheating temperature); Forming stage (5.5 s): Forced convection boundary conditions are applied to the inner wall (convective heat transfer coefficient: 2.0 W / (m²)). 2 The glass melt temperature was linearly reduced from 1100℃ to 700℃; forced convection boundary conditions were applied to the outer wall (convective heat transfer coefficient: 0.15W / (m²)). 2 (⋅K), ambient temperature: 40℃). Cooling stage (3.5 s): Natural convection boundary conditions are applied to the inner wall (convective heat transfer coefficient: 0.015 W / (m²)). 2(⋅K), cold source (ambient) temperature: 40℃); the outer wall boundary conditions remain unchanged; The original mold analysis consisted of 8 molding-cooling cycles (with a relative temperature error of no more than 0.11% during the last four cycles); the mold analysis with the built-in annular cavity consisted of 15 process cycles (with a relative temperature error of no more than 0.13% during the last four cycles). The temperature field obtained from thermal analysis is used as a temperature load and is unidirectionally transferred to the mechanical analysis model to calculate thermal stress and structural deformation.

[0043] (6) Boundary conditions (mechanical analysis): The longitudinal displacement of the bottom of the mold is 0 (Uy = 0, constraining the vertical displacement of the bottom of the mold).

[0044] Simulation results: Maximum Mises thermal stress in solid mold: 176.3 MPa (occurring in the transition zone from the inner neck to the body of the bottle).

[0045] The maximum Mises thermal stress of the mold of this invention is 104.5 MPa (occurring in the transition zone from the inner bottleneck to the bottle body, but the value is significantly reduced).

[0046] Example 2 (Variable Radius Scheme): Differentiated radii are used, for example, 10 mm at the bottom, 10 mm in the middle, and 8 mm at the shoulder. This requires three different sizes of salt cores. In mass production, this not only increases mold costs and material management difficulty, but also reduces production efficiency because different radius cores need to be identified and used during assembly. This solution still falls within the scope of protection of this invention, but Example 1 is preferred.

[0047] The mold geometry parameters in this embodiment are the same as those in Embodiment 1.

[0048] Cavity parameters

[0049] Preparation method: In this embodiment, the coordinates of the three cavity centers are adjusted to (X=51.55, Y=40; X=49.59, Y=120; X=29.96, Y=230), and the radii are adjusted to 10 mm, 10 mm, and 8 mm, respectively. The remaining steps are the same as in Embodiment 1.

[0050] The result obtained in this embodiment 2 is... Figure 1 and Figure 2 Simulation verification of the bottle half-mold 1 shown: In this embodiment, the coordinates of the three cavity centers are adjusted to (X=51.55, Y=40; X=49.59, Y=120; X=29.96, Y=230), and the radii are adjusted to 10 mm, 10 mm, and 8 mm, respectively. The remaining data are consistent with the embodiment.

[0051] Simulation results: Please see Figure 5 and Figure 6 In this embodiment, the maximum Mises thermal stress of the mold is 105.2 MPa (occurring in the transition area from the inner bottleneck to the bottle body, which is basically equivalent to 104.5 MPa in Example 1, proving that the uniform radius scheme can achieve a near-optimal heat insulation effect while avoiding the cost increase caused by multiple specification cores).

[0052] Example 3 (cavity near the outer wall, compared with Example 1): To demonstrate the crucial role of the cavity location, this embodiment places the cavity near the outer wall (5mm from the outer wall), with all other conditions being exactly the same as in Embodiment 1.

[0053] The geometric parameters in this embodiment are the same as those in Embodiment 1.

[0054] Cavity parameters

[0055] Preparation method: In this embodiment, the coordinates of the three cavity centers are adjusted to (X=63,Y=40; X=63,Y=120; X=63,Y=230), respectively, while the radius is kept at 8 mm. The remaining steps are the same as in Embodiment 1.

[0056] Simulation verification: In this embodiment, the coordinates of the three cavity centers are adjusted to (X=63,Y=40; X=63,Y=120; X=63,Y=230), respectively, while the radius remains at 8 mm. The remaining data are consistent with those in Embodiment 1.

[0057] Simulation results: Please see Figure 7 and Figure 8 In this embodiment, the maximum Mises thermal stress of the mold is 124.6 MPa, which is lower than that of the solid mold, but significantly higher than the 104.5 MPa in Embodiment 1. Furthermore, the stress concentration point shifts from the inner wall to the edge of the outer cavity. This is because when the cavity is close to the outer wall, the insulation layer is located on the low-temperature side, resulting in a still significant temperature difference between the inner and outer walls. Additionally, the local weakening of the outer wall material leads to a decrease in stiffness, forcing the thermal stress to concentrate and shift towards the outer wall.

[0058] Please see Figure 9 and Figure 10 , Figure 9 The node temperature (NT11) shown and Figure 10 The Mises thermal stress of 176.3 MPa shown is significantly inferior to that of Example 1 of the present invention. Figure 3 and Figure 4 Example 2 Figure 5 and Figure 6 (shown) and Example 3 ( Figure 7 and Figure 8 Show).

[0059] In summary, the technical solution provided by this invention makes up for the shortcomings of the prior art, successfully completes the invention task, and accurately realizes the technical effects described by the applicant in the above technical effects column.

Claims

1. A low-thermal-stress glass mold comprising bottle half molds (1) used in pairs, each half facing one side of a pair of mold-fitting surfaces (11), the bottle half molds (1) forming a bottle half mold cavity (12), characterized in that: Inside the wall thickness of the bottle half mold (1), along its axial direction, are provided a lower built-in annular cavity (13), a middle built-in annular cavity (14), and a neck and shoulder built-in annular cavity (15), which are independent of each other and spaced apart from each other, and each extends from one side of a pair of mold surfaces (11) to the other side of the mold surface. The openings of the lower built-in annular cavity (13), the middle built-in annular cavity (14), and the neck and shoulder built-in annular cavity (15) are closed at the location of the pair of mold surfaces (11).

2. The low thermal stress glass mold according to claim 1, characterized in that: The wall thickness of the bottle half mold (1) in the region corresponding to the lower built-in annular cavity (13) is configured as the lower wall thickness (16a) of the bottle half mold, the wall thickness in the region corresponding to the middle built-in annular cavity (14) is configured as the middle wall thickness (16b) of the bottle half mold, and the wall thickness in the region corresponding to the neck and shoulder built-in annular cavity (15) is configured as the neck and shoulder wall thickness (16c) of the bottle half mold.

3. The low thermal stress glass mold according to claim 2, characterized in that: The thickness of the lower wall (16a) of the bottle half mold is less than the thickness of the middle wall (16b) of the bottle half mold, and the thickness of the middle wall (16b) of the bottle half mold is less than the thickness of the neck and shoulder wall (16c) of the bottle half mold.

4. The low thermal stress glass mold according to claim 1 or 2, characterized in that: The cross-sectional shape of the lower built-in annular cavity (13), the middle built-in annular cavity (14), and the neck and shoulder built-in annular cavity (15) is circular. The radial distance (L) between the inner wall of the lower built-in annular cavity (13), the inner wall of the middle built-in annular cavity (14), and the inner wall of the neck and shoulder built-in annular cavity (15) and the inner wall of the bottle half mold cavity (12) of the bottle half mold (1) is the same, and the radial distance (L) is 5-8 mm.

5. The low thermal stress glass mold according to claim 4, characterized in that: The radii of the lower built-in annular cavity (13), the middle built-in annular cavity (14), and the neck and shoulder built-in annular cavity (15) are the same.

6. The low thermal stress glass mold according to claim 5, characterized in that: The ratio of the distance between the center of the lower built-in annular cavity (13) and the bottom surface (17a) of the bottle half mold (1) to the height of the bottle half mold (1) is 1:6.9; the ratio of the distance between the center of the middle built-in annular cavity (14) and the bottom surface (17a) of the bottle half mold to the height of the bottle half mold (1) is 1:2.30167; and the ratio of the distance between the center of the neck and shoulder built-in annular cavity (15) and the bottom surface (17a) of the bottle half mold to the height of the bottle half mold (1) is 1:2.

008.

7. The low thermal stress glass mold according to claim 6, characterized in that: The distance between the bottom surface (17a) and the top surface (17b) of the bottle half mold is 276.2 mm, the distance between the center of the lower built-in annular cavity (13) and the bottom surface (17a) of the bottle half mold (1) is 40 mm, the distance between the center of the middle built-in annular cavity (14) and the bottom surface (17a) of the bottle half mold (1) is 120 mm, and the distance between the center of the neck and shoulder built-in annular cavity (15) and the bottom surface (17a) of the bottle half mold (1) is 230 mm.

8. The low thermal stress glass mold according to claim 7, characterized in that: The distance from the center of the lower built-in annular cavity (13) to the central axis (Y) of the bottle half mold cavity (12) is 49.55 mm, the distance from the center of the middle built-in annular cavity (14) to the central axis (Y) of the bottle half mold cavity (12) is 47.59 mm, and the distance from the center of the neck and shoulder built-in annular cavity (15) to the central axis (Y) of the bottle half mold cavity (12) is 29.96 mm.

9. A method for preparing a low thermal stress glass mold as described in claim 1, characterized in that: Includes the following steps: A) Prepare a half-mold casting of a soluble salt core bottle to be installed. In the wall thickness of the half-mold casting, a lower salt core mounting hole, a middle salt core mounting hole, and a neck and shoulder salt core mounting hole are reserved along its axial direction. The lower salt core mounting hole, the middle salt core mounting hole, and the neck and shoulder salt core mounting hole are each made to penetrate from one side of the joint surface of a pair of casting bodies to the other side of the joint surface of a pair of casting bodies, thus obtaining the half-mold casting of the soluble salt core bottle to be installed. B). Prepare a soluble salt core bottle half-mold casting body, embed the pre-made soluble salt core into the lower salt core mounting hole, the middle salt core mounting hole and the neck and shoulder salt core mounting hole respectively, and make the two ends of the soluble salt core protrude out of the opening of the mounting hole and insert into the positioning groove on the parting surface of the corresponding bottle half-mold casting body to obtain a bottle half-mold casting body with soluble salt core installed; C). Casting: The molten metal is poured into the sand mold in the closed state, cooled, solidified and removed from the mold to obtain a bottle half mold (1) with a pair of mold surfaces (11) and forming a bottle half mold cavity (12); D). Dissolve the salt core by using a 40-60℃ warm water dissolution method, immersion dissolution method, pressure spraying method or ultrasonic-assisted dissolution method to dissolve and empty the soluble salt core described in step B). Then, after subsequent processing including heat treatment, a low thermal stress glass mold is obtained, which has a lower built-in annular cavity (13), a middle built-in annular cavity (14) and a neck and shoulder built-in annular cavity (15), and the opening of the annular cavity is closed at a pair of mold mating surfaces (11).

10. The method for preparing a low-thermal-stress glass mold according to claim 9, characterized in that: The soluble salt core mentioned in steps B) and D) is a water-soluble chloride, which is a sodium chloride-based soluble salt.

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