High-pressure forming mold and 3D glass high-pressure forming method

Abstract

The invention provides a high-pressure forming mold and a 3D glass high-pressure forming method. S1, mold preheating is conducted, specifically, an empty upper mold and an empty lower mold are fed into a heating work station, the empty molds are preheated, and moisture in the molds is removed; s2, feeding and mold closing are conducted, specifically, the frit is placed in a lower mold, and mold closing is conducted on an upper mold and the lower mold; s3, glass heating, wherein a heating work station is subjected to stepped temperature rise; s4, primary pressing is conducted, specifically, the upper mold and the lower mold are conveyed to a first high-pressure work station, and primary pressurization is conducted on the upper mold and the lower mold through the first high-pressure work station; s5, secondary pressing is conducted, specifically, the upper mold and the lower mold are conveyed to a second high-pressure work station, and secondary pressurization is conducted on the upper mold and the lower mold through the second high-pressure work station; s6, annealing and cooling, namely cooling a product after the glass is pressed and molded, and progressively reducing the cooling temperature in a stepped manner; and S7, molding and material taking: cooling the molded glass material, and taking the cooled glass material to complete high-pressure molding of the 3D glass.

Description

Technical Field

[0001] The present disclosure relates to the technical field of glass processing equipment, and in particular to a high-pressure molding mold and a method for performing 3D glass high-pressure molding using the high-pressure molding mold. Background Art

[0002] Mobile phones and car glass cover plates have undergone upgrades from flat glass to 3D curved glass and then to surface textured glass. Currently, the surface texture is in the research and development stage. Due to the high molding defect rate, the glass cannot be formed, and there is currently no mass production process on the market for production. The traditional hot bending process is prone to cause glass breakage, cracking and other adverse phenomena, reducing product yield.

[0003] The prior art is disclosed in CN109422445A, which includes the following steps: a preheating step, specifically: the glass plate is preheated in four stages of continuous heating to raise the temperature to 740°C-760°C; a hot bending step, specifically: the preheated glass plate is subjected to two stages of hot bending in sequence to obtain a preliminary bent glass product; a cooling step, but the patent does not preheat the mold when heating the glass. At this time, if there is some moisture inside the mold, the glass material will be heated unevenly, resulting in the glass material bursting and damage during the heating process, thereby successfully reducing the yield of the glass material. Summary of the invention

[0004] A technical problem to be solved by the present disclosure is that in the prior art, glass materials are heated unevenly, resulting in glass materials being cracked and damaged during the heating process.

[0005] In order to solve the above technical problems, a high-pressure forming mold includes an upper mold and a lower mold. A die cavity is arranged in the middle of the upper end surface of the lower mold, and a limiting groove is arranged on the outer wall of the die cavity. A pressing module is arranged in the middle of the lower end surface of the upper mold. The pressing module and the die cavity are clearance-matched, and a limiting block that fits with the limiting groove is arranged on the outer wall of the pressing module. A plurality of through-heating holes are arranged on the pressing module, and a plurality of the heating holes are connected to the die cavity. The upper mold and the lower mold are made of tungsten steel plate.

[0006] In some embodiments, a high pressure forming die is used, comprising the following steps:

[0007] S1: Preheating the mold. Send the empty upper mold and lower mold into the heating station to preheat the empty mold and remove moisture from the mold.

[0008] S2: Loading and closing the mold, placing the glass material in the lower mold, and closing the upper mold and the lower mold;

[0009] S3: Glass heating, the heating station performs step-by-step temperature increase, and the heating station heats the glass materials in the upper mold and the lower mold;

[0010] S4: one-time pressing, conveying the upper mold and the lower mold to the first high-pressure station, and using the first high-pressure station to pressurize the upper mold and the lower mold once;

[0011] S5: Secondary pressing, the upper mold and the lower mold are transported to the second high-pressure station, and the upper mold and the lower mold are pressurized for the second time by the second high-pressure station;

[0012] S6: Annealing and cooling: after the glass is pressed and formed, the product is cooled, and the cooling temperature is gradually reduced in steps;

[0013] S7: Molding and taking out the material. The molded glass material is taken out after cooling. The upper mold and the lower mold are cleaned and preheated again for subsequent processing.

[0014] In some embodiments, in step S1, the temperature of the heating station is divided into two stages:

[0015] In the first stage, the temperature of the heating station gradually increases from room temperature to 400℃~600℃;

[0016] In the second stage, the temperature of the heating station gradually increases from the temperature state of the first stage to 700°C to 900°C.

[0017] In some embodiments, the temperature duration in the second stage is 25 to 35 minutes.

[0018] In some embodiments, in step S2, before the glass material is placed in the lower mold, the inner walls of the upper mold and the lower mold are wiped with dust-free paper, and then the cleaned glass material is placed in the lower mold cavity.

[0019] In some embodiments, in step S3, the step-wise heating stage of the preheating station is as follows:

[0020] In the first stage, the preheating station is heated from room temperature to 110℃~130℃ and maintained for 100s~140s;

[0021] In the second stage, the temperature is heated from the first stage to 580°C to 620°C and maintained for 340s to 380s;

[0022] In the third stage, the temperature is heated from the second stage to 980°C to 1020°C and maintained for 100s to 140s.

[0023] In some embodiments, in the second stage of step S3, the glass material between the upper mold and the lower mold is continuously heated and softened, and the weight of the upper mold itself is used to pre-press the glass material.

[0024] In some embodiments, in step S4, the first high pressure station generates 80 kg to pressurize the upper mold, and the pressing lasts for 120 seconds to complete one pressing.

[0025] In some embodiments, in step S5, the second high pressure station generates 100 kg to pressurize the upper mold, and the pressurization lasts for 360 seconds to complete the secondary pressing.

[0026] In some embodiments, the step-wise cooling stage of the preheating station in step S6 is as follows:

[0027] In the first stage, the temperature of the preheating station is reduced from 1000°C to 600°C;

[0028] In the second stage, the temperature of the preheating station is reduced from 600°C to 120°C;

[0029] In the third stage, the temperature of the preheating station is reduced from 120°C to room temperature.

[0030] Through the above technical solution, the high pressure forming mold and 3D glass high pressure forming method provided by the present disclosure have the following beneficial effects:

[0031] First, in the glass high-pressure forming method of this scheme, before heating the glass material, the mold is preheated first, and the empty upper mold and lower mold are sent to the heating station to preheat the empty mold to remove moisture in the mold to avoid directly throwing in the glass and causing breakage; then the material is loaded and the mold is closed, and the glass material is placed in the lower mold. In this step, the flat glass material is put into the compression mold cavity of the lower mold, and then the upper mold and the lower mold are closed to make the limit groove and the limit block dock.

[0032] Second, in the second stage of step S3 of this scheme, the temperature maintenance time of this stage is longer than that of the other two stages, so as to ensure that the glass material between the upper mold and the lower mold is softened after continuous heating, and the weight of the upper mold itself is used to pre-press the glass material. During the pre-pressing process, the glass material can be bent to about 30%.

[0033] Third: In this scheme, an upper mold and a lower mold are provided, a die cavity is provided in the middle of the upper end surface of the lower mold, a limiting groove is provided on the outer wall of the die cavity, a pressing module is provided in the middle of the lower end surface of the upper mold, the pressing module is gap-matched with the die cavity, a plurality of through-heating holes are arranged on the pressing module, and the plurality of heating holes are connected to the die cavity. The heat outside the upper mold and the lower mold can be evenly transferred to the glass material therein through the provided heating holes, thereby improving the heating efficiency and heating uniformity of the glass material, reducing the time for glass molding and softening, and thus improving the processing efficiency of the equipment. The upper mold and the lower mold are made of tungsten steel plate, which has better flatness under high temperature conditions, and can ensure that the overall force of the mold is uniform, so that the overall effect of 3D glass produced in the same batch is consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 is a schematic block diagram of the steps of the 3D glass high pressure forming method in an embodiment of the present disclosure;

[0036] Figure 2 The structure of the high pressure forming mold in the embodiment of the present disclosure is shown in FIG. Figure 1 ;

[0037] Figure 3 The structure of the high pressure forming mold in the embodiment of the present disclosure is shown in FIG. Figure 2 .

[0038] Description of reference numerals:

[0039] 1. Upper mold; 11. Pressing die block; 12. Limiting block; 13. Heating hole; 2. Lower mold; 21. Pressing die cavity; 22. Limiting groove. DETAILED DESCRIPTION

[0040] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0041] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0042] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0043] In addition, the words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0044] It should also be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0045] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0046] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0047] like Figure 2-3As shown, the high pressure forming mold comprises an upper mold 1 and a lower mold 2, a mold cavity 21 is arranged in the middle of the upper end surface of the lower mold 2, and a limiting groove 22 is arranged on the outer side wall of the mold cavity 21, and a pressing module 11 is arranged in the middle of the lower end surface of the upper mold 1, and the pressing module 11 is clearance-matched with the mold cavity 21, and the pressing module 11 and the mold cavity 21 form a desired pressed curved glass shape, and during the pressing process of the glass, the flattened glass material is put between the pressing module 11 and the mold cavity 21, and the glass material is processed into the desired curved shape under the following process, and the outer side wall of the pressing module 11 is provided with a clearance-matched with the limiting groove 22. The limiting blocks 12 fit together, and the pressing module 11 is provided with a plurality of through heating holes 13, and the plurality of heating holes 13 are connected to the pressing mold cavity 21. The heat holes 13 can evenly transfer the heat outside the upper mold 1 and the lower mold 2 to the glass material therein, thereby improving the heating efficiency and heating uniformity of the glass material, reducing the time of glass molding and softening, and thus improving the processing efficiency of the equipment. The upper mold 1 and the lower mold 2 are made of tungsten steel plate, which has better flatness under high temperature conditions, and can ensure that the overall force of the mold is uniform, so that the overall effect of the 3D glass produced in the same batch is consistent.

[0048] In some embodiments, the upper mold 1 and the lower mold 2 in this solution are concave and convex molds, and the mold gap of the concave and convex molds is designed to be -0.3 pressing instead of the traditional 1:1 pressing. For example, if the glass thickness is 0.7 mm, the mold gap needs to be designed to be 0.4 mm, so that the glass can be fully compressed at the high temperature softening point without breaking;

[0049] like Figure 1-3 As shown, the 3D glass high pressure forming method comprises the following steps:

[0050] S1: Preheating the mold. Send the empty upper mold 1 and the lower mold 2 into the heating station to preheat the empty mold and remove moisture in the mold to avoid breaking the glass when it is directly put into the mold.

[0051] S2: Loading and closing the mold, placing the glass material in the lower mold 2. In this step, the flat glass material is placed in the compression mold cavity 21 of the lower mold 2, and then the upper mold 1 and the lower mold 2 are closed to make the limiting groove 22 and the limiting block 12 butt against each other;

[0052] S3: Heating the glass. The heating station performs step-by-step temperature increase to prevent the temperature from rising too fast, causing uneven heating of the glass material and affecting the processing quality of the formed glass. The heating station heats the glass material in the upper mold 1 and the lower mold 2.

[0053] S4: one-time pressing, conveying the upper mold 1 and the lower mold 2 to the first high-pressure station, using the first high-pressure station to pressurize the upper mold 1 and the lower mold 2 once, and the glass material can be bent to 90% during the one-time pressing process;

[0054] S5: secondary pressing, conveying the upper mold 1 and the lower mold 2 to the second high-pressure station, and performing secondary pressurization on the upper mold 1 and the lower mold 2 by the second high-pressure station. During the secondary pressurization process, the glass material can be bent to 100%, and the pressurization operation of the glass material is completed;

[0055] S6: Annealing and cooling: After the glass is pressed and formed, the product is cooled. The cooling temperature is gradually reduced in steps to prevent the formed glass material from bursting due to excessive cooling.

[0056] S7: Molding and taking out the material. The molded glass material is taken out after cooling, and the upper mold 1 and the lower mold 2 are cleaned and re-preheated for subsequent processing.

[0057] In some embodiments, the temperature of the heating station in step S1 is divided into two stages:

[0058] In the first stage, the temperature of the heating station is gradually increased from room temperature to 400°C to 600°C, with the preferred temperature being 500°C;

[0059] In the second stage, the temperature of the heating station gradually increases from the temperature state of the first stage to 700°C to 900°C, wherein the preferred temperature is 800°C. In the above-mentioned step-by-step temperature adjustment process, the temperatures of the upper mold 1 and the lower mold 2 can be evenly increased, thus preventing the temperature of some areas of the mold from rising and causing deformation of the mold.

[0060] On this basis, the temperature duration in the second stage is 25 to 35 minutes, and the preferred temperature duration is 30 minutes, so as to ensure that the entire mold can be heated evenly and sufficiently according to the shape and volume of the mold.

[0061] In some embodiments, in step S2, before the glass material is placed in the lower mold 2, the inner walls of the upper mold 1 and the lower mold 2 are wiped with dust-free paper, and then the cleaned glass material is placed in the cavity of the lower mold 2, so as to ensure that the upper mold 1 and the lower mold 2 are kept clean and prevent dust and impurities in the upper mold 1 and the lower mold 2 from affecting the processing accuracy of the glass.

[0062] In some embodiments, the step-wise heating stage of the preheating station in step S3 is as follows:

[0063] In the first stage, the preheating station is heated from room temperature to 110°C to 130°C, preferably 120°C, and maintained for 100s to 140s, preferably 120s. The upper mold 1, the lower mold 2 and the glass material therein are fully and evenly preheated during 120s.

[0064] In the second stage, the temperature is heated from the first stage to 580°C to 620°C, preferably 600°C, and maintained for 340s to 380s, preferably 360s, so that the upper mold 1, the lower mold 2 and the glass material therein are fully and evenly preheated for 360s;

[0065] In the third stage, the temperature is heated from the second stage to 980°C to 1020°C, preferably 1000°C, and maintained for 100s to 140s, preferably 120s; the upper mold 1, the lower mold 2 and the glass material therein are fully and evenly preheated in 120s.

[0066] On this basis, in the second stage of step S3, the temperature maintenance time in this stage is longer than that in the other two stages, so as to ensure that the glass material between the upper mold 1 and the lower mold 2 is continuously heated and softened, and the weight of the upper mold 1 itself is used to pre-press the glass material. During the pre-pressing process, the glass material can be bent to about 30%.

[0067] At this time, the softening state of the glass material can be judged by observing the pressing state and the gap between the upper mold 1 and the lower mold 2. For example, the mold gap between the upper mold 1 and the lower mold 2 can be judged by a gap detector or visual inspection. When the glass is not heated, the gap between the upper mold 1 and the lower mold 2 is X. The glass material of the upper mold 1 and the lower mold 2 continues to soften in an environment with a temperature of 600°C. At this time, the glass material is pressurized by the dead weight of the upper mold 1, so that the gap between the upper mold 1 and the lower mold 2 is reduced to 70%X, thereby avoiding the high-pressure breakage of the glass material, thereby greatly improving the yield of 3D glass high-pressure molding.

[0068] In some embodiments, the heating time in the first stage, the second stage and the third stage is set according to the material of the upper mold 1 and the lower mold 2, wherein the heating time calculation formula of the first stage and the third stage is:

[0069]

[0070] where t 总 is the total heating time of the preheating station in the current stage, m is the mold mass; c is the specific heat capacity of the mold material; ΔT2 is the set temperature; ΔT1 is the current temperature; P is the heating power of the preheating station; t 延 The extension time is an appropriate adjustment for the heating power fluctuation of the preheating station and the current temperature. When the heating power of the preheating station is unstable and the current temperature is low, increase t 延 The extended time is used to ensure that the glass material can be heated to the set temperature in the current stage, and to reduce the glass material entering the next stage after reaching the set temperature, thereby improving the processing efficiency of the equipment.

[0071] The calculation formula for the heating time in the second stage is:

[0072]

[0073] where t 总 is the total heating time of the preheating station in the current stage, m is the mold mass; c is the specific heat capacity of the mold material; ΔT2 is the set temperature; ΔT1 is the current temperature; P is the heating power of the preheating station; t 延 The extension time is an appropriate adjustment for the heating power fluctuation of the preheating station and the current temperature. When the heating power of the preheating station is unstable and the current temperature is low, increase t 延 The extension time is to ensure that the glass material can be heated to the set temperature in the current stage; t 压 is the time for the upper mold 1 to pre-press the glass material by its own weight, t 压 The length of time can be adjusted in combination with the mass of the upper mold 1. The greater the mass of the upper mold 1, the shorter the pre-pressing time required. In this scheme, t 压 is 120s.

[0074] In some embodiments, in step S4, the first high pressure station generates 80 kg to pressurize the upper mold 1, and the pressing lasts for 120 seconds to complete one pressing.

[0075] In some embodiments, in step S5 , the second high pressure station generates 100 kg to pressurize the upper mold 1 , and the pressurization lasts for 360 seconds to complete the secondary pressing.

[0076] In some embodiments, the step-wise cooling stage of the preheating station in step S6 is as follows:

[0077] In the first stage, the temperature of the preheating station is reduced from 1000°C to 600°C;

[0078] In the second stage, the temperature of the preheating station is reduced from 600°C to 120°C;

[0079] In the third stage, the temperature of the preheating station is reduced from 120°C to room temperature;

[0080] In this way, the glass material is gradually cooled down, thereby preventing the formed glass material from being cooled down too quickly and causing the glass material to burst.

[0081] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0082] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. High pressure forming die, characterized in that: The invention comprises an upper mold (1) and a lower mold (2), wherein a die cavity (21) is arranged in the middle of the upper end surface of the lower mold (2), and a limiting groove (22) is arranged on the outer side wall of the die cavity (21); a pressing module (11) is arranged in the middle of the lower end surface of the upper mold (1), and the pressing module (11) is clearance-matched with the die cavity (21), and a limiting block (12) which is matched with the limiting groove (22) is arranged on the outer side wall of the pressing module (11); a plurality of through-going heat-receiving holes (13) are arranged on the pressing module (11), and a plurality of the heat-receiving holes (13) are connected to the die cavity (21); and the upper mold (1) and the lower mold (2) are made of tungsten steel plate. 2.3D glass high pressure forming method, characterized in that: The high pressure forming die as claimed in claim 1 comprises the following steps: S1: preheating the mold, sending the empty upper mold (1) and the lower mold (2) into the heating station, preheating the empty mold, and removing moisture in the mold; S2: loading and closing the mold, placing the glass material in the lower mold (2), and closing the upper mold (1) and the lower mold (2); S3: heating the glass, the heating station performs step-by-step temperature increase, and the heating station heats the glass material in the upper mold (1) and the lower mold (2); S4: pressing once, transporting the upper mold (1) and the lower mold (2) to the first high-pressure station, and applying pressure to the upper mold (1) and the lower mold (2) using the first high-pressure station; S5: secondary pressing, transporting the upper mold (1) and the lower mold (2) to the second high-pressure station, and performing secondary pressurization on the upper mold (1) and the lower mold (2) using the second high-pressure station; S6: Annealing and cooling: after the glass is pressed and formed, the product is cooled, and the cooling temperature is gradually reduced in steps; S7: Molding and taking out the material. The molded glass material is taken out after cooling, and the upper mold (1) and the lower mold (2) are cleaned and re-preheated for subsequent processing.

3. The 3D glass high pressure forming method according to claim 2, characterized in that: In step S1, the temperature of the heating station is divided into two stages: In the first stage, the temperature of the heating station gradually increases from room temperature to 400℃~600℃; In the second stage, the temperature of the heating station gradually increases from the temperature state of the first stage to 700°C to 900°C.

4. The 3D glass high pressure forming method according to claim 3, characterized in that: The temperature duration in the second stage is 25 to 35 minutes.

5. The 3D glass high pressure forming method according to claim 2, characterized in that: In step S2, before the glass material is placed in the lower mold (2), the inner walls of the upper mold (1) and the lower mold (2) are wiped with dust-free paper, and then the cleaned glass material is placed in the cavity of the lower mold (2).

6. The 3D glass high pressure forming method according to claim 2, characterized in that: In step S3, the step-wise heating stage of the preheating station is as follows: In the first stage, the preheating station is heated from room temperature to 110℃~130℃ and maintained for 100s~140s; In the second stage, the temperature is heated from the first stage to 580°C to 620°C and maintained for 340s to 380s; In the third stage, the temperature is heated from the second stage to 980°C to 1020°C and maintained for 100s to 140s.

7. The 3D glass high pressure forming method according to claim 5, characterized in that: In the second stage of step S3, the glass material between the upper mold (1) and the lower mold (2) is continuously heated and softened, and the weight of the upper mold (1) is used to pre-press the glass material.

8. The 3D glass high pressure forming method according to claim 2, characterized in that: In step S4, the first high-pressure station generates a pressure of 80 kg to pressurize the upper mold (1) for 120 seconds, completing a pressing operation.

9. The 3D glass high pressure forming method according to claim 2, characterized in that: In step S5, the second high pressure station generates a pressure of 100 kg to pressurize the upper mold (1) for 360 seconds to complete the secondary pressing.

10. The 3D glass high pressure forming method according to claim 2, characterized in that: The step-wise cooling stage of the preheating station in step S6 is as follows: In the first stage, the temperature of the preheating station is reduced from 1000°C to 600°C; In the second stage, the temperature of the preheating station is reduced from 600°C to 120°C; In the third stage, the temperature of the preheating station is reduced from 120°C to room temperature.

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