One-step molded internal heightening half fork and production process thereof

Abstract

The invention relates to a one-step molded height increasing half fork and a production process thereof.The height increasing half fork comprises a half fork body and a midsole paperboard, the half fork body is made of SBS, white oil, polystyrene, an AC foaming agent, a microsphere foaming agent, an ATL nucleating agent, an anti-shrinking agent and a flexibilizer, and the materials are fused according to a proper proportion; the internal heightening half fork can be manufactured by adopting an integrated forming process of the half fork main body and the insole paperboard, and the internal heightening half fork has the performance of high elasticity, low temperature resistance, deformation resistance and long service life.

Description

Technical Field

[0001] The present invention particularly relates to a one-time formed inner heightened half fork and a production process thereof. Background Art

[0002] A half-split shoe is a component inside a shoe that provides a concealed height-enhancing effect and enhances the support of the sole. For example, the document with publication number "CN101579912A" describes a method for making a half-split shoe for a shoe body midsole. The half-split produced by this method primarily consists of a core made of iron or fiberglass strips, a surface material made of cloth, cardboard, or plastic, and an outer layer made of hard plastic. The outer layer of this half-split shoe is made of "hard plastic," which can easily cause permanent deformation after prolonged use, resulting in a "trampled" sole and insufficient elasticity and resilience. Furthermore, in winter or in cold working environments such as cold storage rooms, this half-split shoe easily hardens and becomes brittle, making it prone to cracking or wear. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a one-time formed inner heightened half fork and its production process in view of the deficiencies of the above-mentioned prior art, wherein the inner heightened half fork has the properties of "high elasticity, low temperature resistance, deformation resistance and long life".

[0004] To achieve the above objectives, the present invention provides the following technical solution: a one-step molded inner height-enhanced half fork, comprising a half fork body and a midsole paperboard connected to the half fork body, characterized in that the material formula of the half fork body comprises 36.0%-40.0% SBS, 20.0%-23.0% white oil, 22.0%-26.0% polystyrene, 1.5%-2.1% AC foaming agent, 0.8%-1.2% microsphere foaming agent, 0.2%-0.4% ATL nucleating agent, 4.5%-5.1% anti-shrinkage agent, and 8.0%-8.6% toughening agent.

[0005] This technical solution, through an optimized SBS-based material formula and integrated midsole paperboard, addresses the challenges of the original rigid plastic half-fork, including insufficient elasticity and resilience, brittle hardening at low temperatures, and deformation after prolonged use. 36.0% to 40.0% SBS (styrene-butadiene-styrene block copolymer), a thermoplastic elastomer, combines the high elasticity of rubber with the processability of plastic. Its butadiene segments provide excellent elasticity and resilience to prevent deformation from prolonged use, while the styrene segments provide rigid support. Its low glass transition temperature (approximately -70°C) at low temperatures (e.g., below 0°C) maintains flexibility, addressing the issue of low-temperature brittle cracking. 20.0% to 23.0% white oil acts as a softener, penetrating the SBS molecular chains to reduce intermolecular forces, enhancing the material's softness and ductility, further lowering the glass transition temperature and enhancing flexibility at low temperatures. 22.0% - 26.0% polystyrene acts as a rigid plastic, balancing the high elasticity of SBS and enhancing the material's hardness and support, preventing the half-fork from losing its arch support due to excessive softness. 1.5% - 2.1% AC foaming agent (also known as azodicarbonamide) decomposes during injection molding and produces nitrogen, creating a uniform closed-cell structure. This reduces density, increases elasticity, and distributes pressure across the foot. 0.8% - 1.2% microsphere foaming agent expands upon heating to form finer cells. Together with the AC foaming agent, it creates a "macroporous + microporous" composite structure, optimizing elastic stability and fatigue resistance. 0.2% - 0.4% ATL nucleating agent provides a foaming core, promoting uniform cell nucleation and size refinement, enhancing the material's tear resistance and surface smoothness. 4.5% - 5.1% anti-shrinkage agent inhibits volumetric shrinkage during injection molding and cooling, improving dimensional stability and preventing mismatch with shoe components and surface sink marks. 8.0%-8.6% of a toughening agent (preferably EVA or rubber elastomer) improves the material's elongation at break and impact resistance, enhancing its crack resistance and wear resistance under low temperatures or high stresses. Furthermore, the midsole cardboard, molded in one piece with the fork body, creates a "rigid-flexible" combination through its high-density rigid structure and the fork's elastic body. This provides basic support at the arch to prevent collapse, distributes foot pressure, and reduces localized stress concentration. Heat-melting or mechanical interlocking enhances structural integrity to prevent delamination and fall-off, and the shape is customized to the shoe last to enhance fit with the sole components. Ultimately, the fork's internal height increase features "high elasticity, low-temperature resistance, deformation resistance, and long life." Secondly, when the fork is placed inside the shoe, the midsole cardboard maintains its shape consistent with the shoe's inner cavity, preventing the fork from moving back and forth, allowing it to better fit the sole of the foot.

[0006] The present application can be further configured as follows: a plurality of groups of shock-absorbing holes arranged in a crisscross pattern are provided on the half-fork body, the lower ends of the shock-absorbing holes are open, and the midsole paperboard is provided with clearance grooves corresponding to the plurality of groups of shock-absorbing holes.

[0007] The above technical solution can eliminate the need for the main body of the half-fork for the shock-absorbing holes, thereby reducing the weight of the shoe and making it more comfortable for walking and exercise. Furthermore, a clearance groove is provided on the midsole cardboard for forming the shock-absorbing holes, preventing interference between the midsole cardboard and the mold, which would affect the formation of the shock-absorbing holes.

[0008] The production process of a one-step forming inner heightened half fork is characterized by comprising the following steps: S1. Prepare composite plastic particles and a midsole paperboard. The formula of the composite plastic particles is the material formula of the half-fork body in claim 1 or 2. The midsole paperboard is the midsole paperboard in claim 1 or 2. S2. Open the mold. The injection mold includes an upper mold, a lower mold, and a middle frame distributed between the upper mold and the lower mold. A main molding cavity structure is provided between the upper mold and the middle frame. The midsole paperboard is laid in the main molding cavity structure. S3, mold closing and injection molding, injection pressure is 40-45MPa, flow rate is 40-50cm / s, and injection time is 10 seconds; S4. After cooling, open the mold and take out the finished product; S5. After trimming the feed and exhaust heads, arrange and pack them.

[0009] Using the above technical solution, step S1 utilizes optimized composite plastic particles (containing SBS, white oil, polystyrene, and other ingredients) and a customized midsole cardboard (with a recessed groove and an annular peripheral structure) to ensure the half-fork body exhibits excellent properties such as high elasticity, low-temperature resistance, and deformation resistance. In step S2, the mold comprises an upper mold, a lower mold, and a middle frame. The midsole cardboard is laid out in the main molding cavity, and the middle frame divides the space between the midsole cardboard and accurately positions it to prevent shifting or wrinkling, ensuring that the half-fork body and the midsole cardboard are integrally formed. In step S3, the injection molding parameters are set at 40-45 MPa, a flow rate of 40-50 cm / s, and an injection time of 10 seconds to ensure that the composite plastic particles evenly fill the mold cavity, protect the molecular chains of elastic components such as SBS, promote the fusion of the AC foaming agent and the microsphere foaming agent, and form a "macroporous + microporous" composite cell structure. The anti-shrinkage agent also enhances the effect of the anti-shrinkage agent to inhibit cooling shrinkage and avoid dimensional deviation. After cooling in step S4, the mold is opened. Slow solidification is used to avoid internal stress concentration and surface sink marks, maintaining elastic properties. The demolding process is optimized by utilizing the midframe structure and shock-absorbing hole opening design to reduce damage or deformation caused by forced demolding. In step S5, the feed and exhaust nozzles are trimmed and then packed. Excess material is removed to avoid burrs and dimensional deviations, ensuring the consistency of the finished product.

[0010] The present application can be further configured as follows: the main molding cavity structure in step S2 includes a forefoot accommodating cavity corresponding to the forefoot and a half-fork injection molding cavity corresponding to the heel, and the forefoot accommodating cavity and the half-fork injection molding cavity are connected to each other. After mold closing in step S3, the outer peripheral surface of the forefoot part of the midsole paperboard is tightly fitted with the inner wall of the forefoot accommodating cavity.

[0011] Using this technical solution, the main molding cavity is divided into a "forefoot receiving cavity" corresponding to the forefoot and a "half-fork injection molding cavity" corresponding to the heel. The forefoot requires rigid support (composed of the midsole cardboard and not injected with molding material), while the heel requires elastic cushioning and height enhancement (composed of the half-fork body molded from composite plastic particles and injected with molding material). The forefoot receiving cavity and the half-fork injection molding cavity are interconnected to accommodate the midsole cardboard and prevent breakage in the middle. A "tight fit" is achieved through mechanical compression, firmly securing the forefoot portion of the midsole cardboard within the forefoot receiving cavity. This prevents the midsole cardboard from shifting or wrinkling due to the impact of the hot, molten injection molding material during the injection molding process (displacement could result in a loose connection between the half-fork body and the midsole cardboard or structural deviation). This ensures precise integration of the midsole cardboard and the half-fork body (for example, alignment of the clearance groove with the shock-absorbing hole), enhancing the structural stability of the finished half-fork.

[0012] The present application can be further configured as follows: the lower mold in step S2 is provided with a column structure corresponding to the half-fork injection cavity, and the half-fork injection cavity is provided with a column matching hole passing through the middle frame; after step S3, when the mold is closed, the column structure passes through the column matching hole until it is inserted into the half-fork injection cavity.

[0013] By adopting the above technical solution, the half fork with the midsole cardboard is integrated into one, and the bottom of the half fork body is provided with a shock-absorbing hole, which not only ensures the shape, position and size accuracy of the shock-absorbing hole, but also avoids the structural damage caused by post-processing, and ultimately improves the shock-absorbing effect and durability of the half fork body.

[0014] The present application can be further configured as follows: in step S3, the injection molding machine is first heated to the set 4 temperature sections, and injection molding is started after the temperature reaches 158°C for section 1, 160°C for section 2, 160°C for section 3, and 155°C for section 4.

[0015] Using the above technical solution, Section 1 is the feed section near the hopper, with a temperature set at 158°C (slightly above the glass transition temperature of the composite plastic particles) to prevent feed blockage caused by premature melting of the material and initiate initial softening. The glass transition temperature of composite plastic particles (including SBS, polystyrene, etc.) is typically between 80-120°C. 158°C allows them to begin to soften but not fully melt, maintaining fluidity between particles and preventing particles from clumping due to high temperatures. (If the temperature is too high, such as exceeding 200°C, the material may melt and clump at the hopper mouth, preventing smooth entry into the barrel.) When the initially softened particles enter the next section, they absorb heat more quickly to complete melting, shortening the overall heating time and improving production efficiency. Sections 2 and 3 are the melting sections, with a temperature stabilized at 160°C to ensure complete melting of the material and activate the activity of key ingredients (such as the foaming agent), while avoiding overheating and degradation. The temperature of 160°C covers the melting range of composite plastic particles (SBS melts at approximately 100-130°C, and polystyrene at approximately 210°C, but the overall melting temperature decreases after blending). At this temperature, low-melting-point components like SBS and white oil completely melt, while high-molecular-weight components like polystyrene begin to soften. Screw shear and mixing form a uniform melt, preventing the presence of unmelted particles (which can cause surface pitting or structural weakness in the finished product). The decomposition temperature of AC foaming agents typically ranges from 160-200°C (depending on the type). 160°C is close to its decomposition threshold but does not trigger a violent reaction, maintaining its "ready-to-activate" state. This prevents both premature decomposition (failure to form cells) caused by temperatures too low (e.g., <150°C) and premature decomposition (gas escape and insufficient foaming in the mold) caused by temperatures too high (e.g., >170°C). Section 4, near the nozzle exit, cools to 155°C to control melt viscosity, prevent material degradation, and preserve foaming agent activity. When the melt flows through the nozzle, the temperature of 155°C is slightly lower than that in the melting zone (160°C). This appropriately increases the melt viscosity (reducing fluidity) and avoids "drooling" (material dripping from the nozzle before injection, causing mold contamination or fill deviation) caused by too low viscosity. Furthermore, moderate viscosity (combined with an injection pressure of 40-45 MPa) ensures stable melt injection into the mold cavity, preventing underfill and flash. SBS is susceptible to thermo-oxidative degradation (molecular chain breakage and decreased elasticity) when exposed to high temperatures (>160°C) for extended periods. A low temperature of 155°C shortens the time the material remains at high temperatures at the nozzle (during the injection cycle), reducing the risk of degradation and preserving the elastic properties of SBS. Once the melt enters the mold, the mold temperature (typically above room temperature but below barrel temperature) and the injection pressure work together to achieve the decomposition conditions of the AC foaming agent within the mold (rather than at the nozzle) (a temperature + pressure trigger), ensuring uniform gas distribution and forming a composite "macro- and micro-pore" cellular structure (improving elastic cushioning properties).The four-stage temperature can achieve "pre-melting to prevent clogging - homogenization to maintain activity - viscosity control to inhibit degradation", which not only ensures the uniformity of material melting and the performance stability of the main components (such as SBS and foaming agent), but also optimizes the injection molding and filling effect, and ultimately realizes that the molded half-fork body has the performance of "high elasticity, high shock absorption, and high precision".

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a mold explosion according to a fourth embodiment of the present invention; Figure 2 Schematic diagram of the middle frame and lower mold closing in embodiment 4 of the present invention; Figure 3 Schematic diagram of the inner heightened half fork structure of embodiments 1 to 3 of the present invention; Figure 4 This is a flow chart of the fourth embodiment of the present invention.

[0018] Reference numerals: half-fork main body 1, midsole cardboard 2, shock-absorbing hole 3, upper mold 4, middle frame 5, lower mold 6, forefoot accommodating cavity 7, half-fork injection molding cavity 8, column structure 9, column matching hole 10. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Example 1: Figure 3 The illustrated single-piece, internally raised half fork shoe comprises a half fork body 1 and a midsole cardboard 2 connected to the body. The body 1 is provided with multiple groups of shock-absorbing holes 3 arranged in a crisscross pattern, each with an open bottom. The midsole cardboard 2 has recesses corresponding to these groups of holes 3. The holes 3 eliminate material from the body 1, reducing the shoe's weight and making it more comfortable for walking and exercising. Furthermore, recesses are provided in the midsole cardboard 2 to form the holes 3 and prevent interference between the midsole cardboard 2 and the mold, which could affect the formation of the holes 3.

[0021] The material formula of the half fork body 1 includes 38.4% SBS, 21.4% white oil, 24.0% polystyrene, 1.8% AC foaming agent, 1.0% microsphere foaming agent, 0.3% ATL nucleating agent, 4.8% anti-shrinkage agent, and 8.3% toughening agent.

[0022] In this embodiment 1, SBS (38.4%) provides high elasticity and resilience to avoid deformation caused by long-term trampling, and can still maintain flexibility (glass transition temperature is about -70°C) at low temperatures (below 0°C) to prevent brittle cracking; white oil (21.4%) acts as a softener to reduce intermolecular forces and improve the softness and ductility of the material; polystyrene (24.0%) balances the high elasticity of SBS to ensure arch support; AC foaming agent (1.8%) decomposes to produce nitrogen to form a closed-cell structure, and microsphere foaming agent (1.0%) forms fine micropores. The two work together to construct a "macropore + micropore" composite foam structure to optimize elastic stability; ATL nucleating agent (0.3%) promotes uniform nucleation of foam cells and refines their size to enhance tear resistance; anti-shrinkage agent (4.8%) inhibits cooling shrinkage to ensure dimensional stability; toughening agent (8.3%) improves impact resistance and wear resistance. The comprehensive performance is balanced in elasticity, support, low-temperature flexibility, anti-deformation, dimensional stability and wear resistance, suitable for daily wear needs.

[0023] Example 2: Figure 3 The one-step molded inner height-enhanced half fork shown includes a half fork main body 1 and a midsole cardboard 2 connected to the half fork main body 1. The half fork main body 1 is provided with a plurality of groups of shock-absorbing holes 3 arranged in a criss-cross pattern. The lower ends of the shock-absorbing holes 3 are open, and the midsole cardboard 2 is provided with clearance grooves corresponding to the plurality of groups of shock-absorbing holes 3.

[0024] The material formula of the half fork body 1 includes 38.0% SBS, 21.5% white oil, 24.0% polystyrene, 1.8% AC foaming agent, 1.0% microsphere foaming agent, 0.3% ATL nucleating agent, 4.8% anti-shrinkage agent, and 8.6% toughening agent.

[0025] In Example 2, SBS (38.0%) provides basic elasticity and resilience; the proportion of white oil (21.5%) is increased compared to Example 1, resulting in a stronger softening effect, a softer material, and improved low-temperature flexibility. Polystyrene (24.0%), AC blowing agent (1.8%), microsphere blowing agent (1.0%), and ATL nucleating agent (0.3%) are consistent with Example 1, providing stable support and foaming effects. The anti-shrinkage agent (4.8%) provides the same shrinkage inhibition ability and good dimensional stability. The toughening agent (8.6%) has the highest proportion, resulting in improved impact resistance and abrasion resistance. This overall performance maintains elasticity and support while also enhancing softness, low-temperature flexibility, and impact resistance, making it suitable for winter or high-stress environments (such as mountaineering and hiking).

[0026] Example 3: Figure 3 The one-step molded inner height-enhanced half fork shown includes a half fork main body 1 and a midsole cardboard 2 connected to the half fork main body 1. The half fork main body 1 is provided with a plurality of groups of shock-absorbing holes 3 arranged in a criss-cross pattern. The lower ends of the shock-absorbing holes 3 are open, and the midsole cardboard 2 is provided with clearance grooves corresponding to the plurality of groups of shock-absorbing holes 3.

[0027] The material formula of the half fork body 1 includes 39.0% SBS, 22.0% white oil, 23.0% polystyrene, 2.0% AC foaming agent, 1.1% microsphere foaming agent, 0.3% ATL nucleating agent, 4.6% anti-shrinkage agent, and 8.0% toughening agent.

[0028] In Example 3, SBS (39.0%) has the highest proportion, resulting in superior elasticity and resilience, and outstanding low-temperature flexibility. White oil (22.0%) has the highest proportion, making the material softer and more ductile. Polystyrene (23.0%) has a slightly lower proportion, offering slightly weaker support but still meeting requirements. The proportions of AC foaming agent (2.0%) and microsphere foaming agent (1.1%) have increased slightly, generating more gas upon decomposition, resulting in more uniform "macropore + micropore" composite cells and better elastic stability and fatigue resistance. The proportion of anti-shrinkage agent (4.6%) has decreased slightly, resulting in slightly weaker dimensional stability. The proportion of toughening agent (8.0%) is the lowest, resulting in slightly weaker impact resistance and abrasion resistance. The overall performance demonstrates superior elasticity, softness, low-temperature flexibility, and fatigue resistance, making it suitable for scenarios requiring high elastic cushioning (such as running and jumping).

[0029] Example 4: Figure 1 、 2 The production process of the one-step forming inner heightened half fork shown in 4 specifically comprises the following steps: S1. Prepare composite plastic particles and midsole paperboard 2. The formula of the composite plastic particles is the same as the material formula of the half-fork body 1 in any one of Examples 1 to 3. The midsole paperboard 2 is the same as the midsole paperboard 2 in any one of Examples 1 to 3.

[0030] S2. Open the mold. The injection mold includes an upper mold 4, a lower mold 6, and a middle frame 5 distributed between the upper mold 4 and the lower mold 6. A main molding cavity structure is provided between the upper mold 4 and the middle frame 5. The main molding cavity structure includes a forefoot accommodating cavity 7 corresponding to the forefoot and a half-fork injection molding cavity 8 corresponding to the heel. The forefoot accommodating cavity 7 and the half-fork injection molding cavity 8 are interconnected. The midsole paperboard 2 is laid in the main molding cavity structure. The lower mold 6 is provided with a column structure 9 corresponding to the half-fork injection molding cavity 8. The half-fork injection molding cavity 8 is provided with a column matching hole 10 that passes through the middle frame 5. After closing the mold in step S3, the column structure 9 is inserted into the column matching hole 10.

[0031] S3. Mold closing and injection molding. After mold closing, the outer peripheral surface of the forefoot portion of the midsole paperboard 2 is tightly attached to the inner wall of the forefoot accommodating cavity 7. The injection molding machine is first heated to the set four temperature levels. After the temperature reaches 158°C in level 1, 160°C in level 2, 160°C in level 3, and 155°C in level 4, injection molding begins. The injection pressure is 40-45 MPa, the flow rate is 40-50 cm / s, and the injection time is 10 seconds.

[0032] S4. After cooling, the mold is opened. The specific demolding process is as follows: First, open the upper mold 4 to separate it from the middle frame 5. The upper mold 4 is connected to an ejector pin. After the upper mold 4 is opened, the half fork is retained within the middle frame 5. Then, open the middle frame 5. Because the middle bottom cardboard 2 and the half fork body are formed within the half fork injection cavity 8, the half fork remains in the middle frame 5. Simultaneously, the column structure 9 of the lower mold 6 slowly withdraws from the column matching hole 10 of the half fork injection cavity 8 during the opening of the middle frame 5. Because the shock-absorbing hole 3 at the bottom of the half fork body 1 is open at the bottom (matching the shape of the column structure 9), the column structure 9 can be disengaged unimpeded along the open direction during withdrawal, avoiding tearing or deformation of the edge of the shock-absorbing hole 3 due to forced core pulling. The finished product can be removed directly by hand.

[0033] S5. After trimming the feed and exhaust heads, arrange and pack them.

Claims

1. A one-step molded inner height-enhancing half fork, comprising a half fork body and a midsole paperboard connected to the half fork body, characterized in that: The material formula of the half fork body includes 36.0%-40.0% of SBS, 20.0%-23.0% of white oil, 22.0%-26.0% of polystyrene, 1.5%-2.1% of AC foaming agent, 0.8%-1.2% of microsphere foaming agent, 0.2%-0.4% of ATL nucleating agent, 4.5%-5.1% of anti-shrinkage agent, and 8.0%-8.6% of toughening agent.

2. The one-step formed inner heightened half fork according to claim 1, characterized in that: The half-fork body is provided with a plurality of shock-absorbing holes arranged in a crisscross pattern, the lower ends of the shock-absorbing holes are open, and the midsole paperboard is provided with recesses corresponding to the plurality of shock-absorbing holes.

3. One-step forming inner heightened half fork production process, characterized by: The following steps are included: S1. Prepare composite plastic particles and a midsole paperboard. The formula of the composite plastic particles is the material formula of the half-fork body in claim 1 or 2. The midsole paperboard is the midsole paperboard in claim 1 or 2. S2. Open the mold. The injection mold includes an upper mold, a lower mold, and a middle frame distributed between the upper mold and the lower mold. A main molding cavity structure is provided between the upper mold and the middle frame. The midsole paperboard is laid in the main molding cavity structure. S3, mold closing and injection molding, injection pressure is 40-45MPa, flow rate is 40-50cm / s, and injection time is 10 seconds; S4. After cooling, open the mold and take out the finished product; S5. After trimming the feed and exhaust heads, arrange and pack them.

4. The production process of one-step forming inner heightened half crotch according to claim 3, characterized in that: The main molding cavity structure in step S2 includes a forefoot accommodating cavity corresponding to the forefoot and a half-fork injection molding cavity corresponding to the heel. The forefoot accommodating cavity and the half-fork injection molding cavity are connected to each other. After the mold is closed in step S3, the outer peripheral surface of the forefoot part of the midsole paperboard is tightly fitted with the inner wall of the forefoot accommodating cavity.

5. The production process of one-step forming inner height-enhanced half crotch according to claim 3, characterized in that: The lower mold in step S2 is provided with a column structure corresponding to the half-fork injection cavity, and the half-fork injection cavity is provided with a column matching hole passing through the middle frame. After the mold is closed in step S3, the column structure passes through the column matching hole until it is inserted into the half-fork injection cavity.

6. The production process of one-step forming inner heightened half crotch according to claim 3, characterized in that: In step S3, the injection molding machine is first heated to the set 4 temperature stages, and injection molding is started after the temperature reaches 158°C for stage 1, 160°C for stage 2, 160°C for stage 3, and 155°C for stage 4.

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