Energy-saving secondary forming mechanism of cable accessory, processing equipment and secondary forming method

Abstract

The application provides an energy-saving secondary forming mechanism of a cable accessory, a processing device and a secondary forming method, and relates to the technical field of processing devices. The energy-saving secondary forming mechanism comprises a goods shelf, a heat preservation box, a pre-heating assembly and a forming assembly. The heat preservation box is used for placing the goods shelf to preserve the cable accessory after primary forming. The pre-heating assembly comprises a pre-heating box body, a driving part and multiple spacers. The pre-heating box body has a feeding end and a discharging end arranged oppositely. Multiple heating stations are arranged in the pre-heating box body. The high-temperature waste gas flows from the discharging end to the feeding end, so that the temperatures of the multiple heating stations form a temperature gradient. The goods shelf passes through each heating station from the feeding end to the discharging end under the action of the driving part, realizes step-by-step heating, solves the delamination problem caused by too fast heating, enables the oven to be heated at high temperature, shortens the secondary forming time and improves the production efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of processing equipment, and specifically relates to an energy-saving secondary forming mechanism, processing equipment and secondary forming method for cable accessories. Background Technology

[0002] Rubber cable accessories are critical insulation components in power transmission and distribution systems. The rubber parts used in cable accessories must undergo a primary molding and a secondary vulcanization process to meet insulation performance, aging resistance, and electrical performance standards.

[0003] Currently, the industry generally uses a traditional intermittent production process: rubber raw materials are mixed and molded at a process temperature of approximately 100℃ in a single molding process, without any insulation measures, allowing the products to dissipate heat naturally in the workshop environment; after accumulating a sufficient batch, they are uniformly sent to a hot air oven for prolonged baking at a high temperature of 160℃-180℃ to improve product performance. During the secondary molding process, excessively rapid heating can easily cause a decrease in the adhesion of rubber inserts, or even delamination and detachment, resulting in defective products. Related technologies often address the problem of excessively rapid heating by lowering the oven temperature and extending the heating time, but this results in low production efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an energy-saving secondary molding mechanism for cable accessories. Under the action of the driving component, the shelf passes through each heating station from the feeding end to the discharging end in sequence to achieve stepped heating, solve the problem of layering caused by excessive heating, enable the oven to heat at high temperature, shorten the secondary molding time, and improve production efficiency.

[0005] The technical solution adopted to solve the above-mentioned technical problems is as follows: A first aspect of the present invention provides an energy-saving secondary molding mechanism for cable accessories, comprising: Shelves for accommodating multiple cable accessories; An insulated box is used to hold the shelf to insulate the cable accessories after they have been molded in one piece; A preheating assembly includes a preheating chamber, a driving component, and multiple spacers. The preheating chamber has an inlet and an outlet opposite to each other, and the outlet is provided with an air inlet. The preheating chamber contains multiple heating stations arranged in a row. Multiple spacers are spaced apart within the preheating chamber. A spacer is positioned between adjacent heating stations. The driving component drives a shelf to move from the inlet to the outlet, so that the shelf passes sequentially through each heating station. A molding assembly includes an oven having an air outlet and an air inlet connected together; the oven is used to heat the cable accessory transferred from the discharge end to the molding assembly.

[0006] According to an embodiment of the present invention, the energy-saving secondary molding mechanism for cable accessories has the spacer rotatably connected to the top wall of the preheating box.

[0007] According to an embodiment of the present invention, the energy-saving secondary molding mechanism for cable accessories includes a preheating assembly further comprising a plurality of limiting blocks, wherein the limiting blocks and the spacers are respectively provided in a corresponding manner; the limiting blocks are disposed on the top wall of the preheating chamber, and the limiting blocks are located on the side of the corresponding spacers near the feeding end.

[0008] According to an embodiment of the present invention, the energy-saving secondary forming mechanism for cable accessories includes a driving component comprising a plurality of conveying rollers arranged in the preheating chamber; the plurality of conveying rollers rotate to drive the shelf to move within the preheating chamber.

[0009] According to an embodiment of the present invention, an energy-saving secondary molding mechanism for cable accessories is provided in which multiple observation windows are provided inside the preheating chamber, and the observation windows and the heating stations are provided in a one-to-one correspondence.

[0010] According to an embodiment of the present invention, an energy-saving secondary molding mechanism for cable accessories includes a temperature sensor installed inside the insulation box, the temperature sensor being used to acquire the temperature inside the insulation box.

[0011] According to an embodiment of the present invention, an energy-saving secondary molding mechanism for cable accessories is provided in an insulation box, wherein a plurality of rolling rollers are arranged on the bottom wall of the insulation box.

[0012] A second aspect of the present invention provides a processing apparatus for cable accessories, including a forming mold and an energy-saving secondary forming mechanism for the cable accessories described in any of the first aspects.

[0013] The third embodiment of the present invention provides a secondary molding method for cable accessories, comprising: The cable accessories, after being formed in one piece, are placed on a shelf inside an insulated box, and the cable accessories are insulated using the insulated box. The high-temperature exhaust gas from the secondary molding process is introduced into the discharge end of the preheating chamber; Place the shelf inside the insulated box into the preheating box; The drive unit drives the shelf to move from the feeding end to the discharging end, so that the shelf passes through each heating station in sequence; Remove the shelf from the discharge end and place it in the oven for heating.

[0014] According to an embodiment of the present invention, a secondary molding method for cable accessories includes a shelf having multiple placement positions; the step of removing the shelf from the insulation box and placing the shelf into the preheating box via the feeding end includes: If multiple of the placement positions contain cable accessories, the shelf inside the insulation box is removed and placed into the preheating box from the feeding end.

[0015] The present invention has at least the following beneficial effects: By setting up shelves and insulated boxes, the cable accessories after the first molding can be centrally insulated and stored, effectively preventing sudden temperature drops during transportation or waiting, and providing stable initial temperature conditions for subsequent secondary molding. During the secondary molding process, the high-temperature exhaust gas generated during the oven operation is introduced into the preheating box to preheat the cable accessories using the oven's waste heat, effectively utilizing residual heat and achieving energy-saving and consumption-reducing benefits. The high-temperature exhaust gas flows from the discharge end to the feed end, creating a temperature gradient across multiple heating stations. Under the action of the drive components, the shelves pass through each heating station sequentially from the feed end to the discharge end, achieving stepped heating and solving the problem of stratification caused by excessively rapid heating. This allows the oven to heat at high temperatures, shortening the secondary molding time and improving production efficiency. The use of spacers reduces heat crosstalk between different heating stations. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a schematic diagram of the overall structure of the energy-saving secondary molding mechanism for cable accessories provided in an embodiment of the present invention; Figure 2 This is a flowchart of the secondary molding method for cable accessories provided in the embodiments of the present invention.

[0017] The following labels are shown in the attached diagram: 100. Shelves; 200. Insulation box; 210. Rolling roller; 300. Preheating chamber; 310. Feeding end; 311. Exhaust port; 312. Exhaust pipe; 313. Second connecting valve; 320. Discharge end; 321. Air inlet; 322. Air inlet pipe; 323. First connecting valve; 330. Heating station; 340. Observation window; 350. Conveyor roller; 400. Spacers; 500, limit block; 600. Oven. Detailed Implementation

[0018] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0020] In the description of this invention, the use of terms such as "a number" means one or more, with "more than" meaning two or more. Terms like "greater than," "less than," and "exceeding" are understood to exclude the stated number, while terms like "above," "below," and "within" are understood to include the stated number. The use of terms like "first," "second," and "third" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, the number of indicated technical features, or the sequential relationship between indicated technical features.

[0021] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0022] Reference Figures 1 to 2 The following are several embodiments of the energy-saving secondary molding mechanism, processing equipment and secondary molding method of the cable accessories of the present invention.

[0023] like Figure 1As shown, the energy-saving secondary molding mechanism for cable accessories according to a first aspect embodiment of the present invention includes a shelf 100, an insulation box 200, a preheating component, and a molding component. The shelf 100 is used to accommodate multiple cable accessories; the insulation box 200 is used to place the shelf 100 to insulate the cable accessories after one-time molding; the preheating component includes a preheating chamber 300, a driving component, and multiple spacers 400. The preheating chamber 300 has a feed end 310 and a discharge end 320 arranged opposite to each other, and the discharge end 320 is provided with an air inlet 321; the preheating chamber 300 is provided with multiple heating elements. The heating station 330 is arranged in a row; multiple spacers 400 are spaced apart in the preheating chamber 300; a spacer 400 is provided between two adjacent heating stations 330; a driving component is used to drive the shelf 100 to move in the direction from the feeding end 310 to the discharging end 320, so that the shelf 100 passes through each heating station 330 in sequence; the forming assembly includes an oven 600, the oven 600 has an air outlet, and the air outlet and the air inlet 321 are connected; the oven 600 is used to heat the cable accessories transferred from the discharging end 320 to the forming assembly.

[0024] By setting up the shelf 100 and the heat preservation box 200, the cable accessories after one-time molding can be centrally heat-preserved and stored, effectively avoiding a sudden drop in temperature during the transfer or waiting process, and providing stable initial temperature conditions for subsequent secondary molding. During the secondary molding process, the high-temperature exhaust gas generated by the oven 600 is introduced into the preheating box 300 to utilize the waste heat of the oven 600 to preheat the cable accessories, effectively utilizing residual heat and achieving energy saving and consumption reduction benefits. The high-temperature exhaust gas flows from the discharge end 320 to the feed end 310, creating a temperature gradient between the multiple heating stations 330. Under the action of the drive component, the shelf 100 passes through each heating station 330 sequentially from the feed end 310 to the discharge end 320, achieving stepped heating, solving the problem of layering caused by excessive heating, allowing the oven 600 to heat at high temperatures, shortening the secondary molding time, and improving production efficiency. By setting up the spacer 400, heat crosstalk between different heating stations 330 can be reduced.

[0025] The preheating chamber 300 has an inlet at its feed end 310 and an outlet at its discharge end 320. An inlet door and an outlet door are rotatably connected to the preheating chamber; the inlet door opens or closes the feed end, and the outlet door opens or closes the outlet. The cable accessories, after one-time molding, are hot-formed rubber parts. These are placed on a shelf 100; the shelf 100 has multiple layers (e.g., four layers), with multiple placement positions on each layer for placing the cable accessories. The insulation chamber 200 includes an outer shell and insulation material, which is located on the inner wall of the outer shell. For example, the insulation material can be insulation cotton, polyurethane foam, or rubber-plastic foam. The insulation chamber 200 reduces the temperature drop of the hot-formed rubber parts. The drying oven 600 is the heat source for secondary molding. Depending on the type of rubber, the temperature of the drying oven 600 can be set between 160℃ and 180℃, and the operating time of the drying oven 600 is between 2 hours and 4 hours. The embodiments of the present invention also include an air intake pipe 322 and a first connecting valve 323. The air intake pipe 322 is connected to the air intake port 321 and the air intake pipe 322 through the first connecting valve 323. The first connecting valve 323 is used to control the opening or closing of the air intake port 321. The embodiments of the present invention also include an exhaust pipe 312 and a second connecting valve 313. The feed end 310 of the preheating box 300 is provided with an exhaust port 311. The exhaust pipe 312 is connected to the exhaust port 311 and the exhaust pipe 312 through the second connecting valve 313. The second connecting valve 313 is used to control the opening or closing of the exhaust port 311. High-temperature exhaust gas flows from the discharge end 320 to the feed end 310 and is discharged through the exhaust pipe 312 of the feed end 310, so that the temperature of the discharge end 320 is higher than that of the feed end 310, thereby forming a temperature gradient in the multiple heating stations 330. The temperature of the heating station 330 near the discharge end 320 is higher than that of the heating station 330 near the feed end 310. The shelf 100 moves from the feed end 310 toward the discharge end 320, so that the shelf 100 is heated sequentially at different heating stations 330, thereby gradually heating the cable accessories after one-time molding.

[0026] In related technologies, rubber raw materials are mixed and molded at a process temperature of approximately 100°C. The temperature of the hot-formed rubber parts upon demolding is 95°C-100°C. After accumulating a sufficient batch, they are uniformly sent to a hot air oven. During the waiting period for a sufficient batch to accumulate, the cable accessories are not insulated and are allowed to dissipate heat naturally in the workshop environment. Before entering the hot air oven, the temperature of the first-molded cable accessories is usually only 25°C-42°C. The hot air oven bakes at a constant temperature of 160°C-180°C for a long time, which causes the temperature to rise too quickly during the second molding. This can easily lead to a decrease in the adhesion of the rubber inserts or even delamination and detachment, resulting in defective products. This problem is often solved by lowering the oven temperature and extending the baking time, which reduces production efficiency.

[0027] This invention uses an insulated box 200 to keep the cable accessories after primary molding warm, and a preheating box 300 to gradually increase the temperature, raising the blank temperature of the cable accessories entering the secondary molding stage from 25℃-42℃ to 86℃-95℃. This reduces the working time of the oven 600 during secondary molding from 2-4 hours to 1.2-2.4 hours, saving 40% of the oven's energy. This application uses an insulated box 200 to keep the cable accessories after primary molding warm, and a preheating box 300 to provide multi-stage heating, resulting in a smaller temperature difference during secondary molding. This achieves slow and uniform heating of the product, thereby increasing the insert peel strength by more than 3N / mm, shortening the heating time in the oven 600, and improving production efficiency.

[0028] like Figure 1 As shown, in some embodiments, the spacer 400 is rotatably connected to the top wall of the preheating chamber 300. When the shelf 100 moves from the inlet end 310 to the outlet end 320, the shelf 100 pushes the spacer 400 upward to prevent the spacer 400 from obstructing the movement of the shelf 100; after the shelf 100 moves from one heating station 330 to another heating station 330, the spacer 400 between the two heating stations 330 naturally droops under gravity to continue isolating the two heating stations 330. The spacer 400 is a polyurethane board. In this embodiment, two spacers 400 are provided inside the preheating chamber 300, corresponding to two heating stations 330. In other embodiments, three, four, or five spacers 400 can be provided; the present invention does not particularly limit the number of spacers 400. The edges of the spacers 400 can be rounded to prevent damage to cable accessories during transport.

[0029] like Figure 1 As shown, in some embodiments, the preheating assembly further includes multiple limiting blocks 500, with each limiting block 500 corresponding to a spacer 400. The limiting blocks 500 are located on the top wall of the preheating chamber 300, and are positioned on the side of the corresponding spacer 400 closest to the feed end 310. This restricts the rotation direction of the spacer 400, preventing it from rotating towards the feed end 310 under the influence of high-temperature exhaust gas, thus ensuring the effective spacing of the spacer 400. In this embodiment, two limiting blocks 500 are provided.

[0030] In some embodiments, the driving component includes a plurality of conveying rollers 350 arranged within the preheating chamber 300; the plurality of conveying rollers 350 rotate to drive the shelf 100 to move within the preheating chamber 300. By rotating the plurality of conveying rollers to drive the shelf 100 to move within the preheating chamber 300, a continuous and automated conveying process can be achieved, reducing manual intervention and improving production efficiency; the conveying rollers are electric rollers in the prior art, which are driven by an internal motor to achieve their own rotation; in other embodiments, the driving component further includes a motor, a transmission chain, and a plurality of transmission sprockets, with each transmission sprocket and transmission roller connected in a corresponding manner, the transmission chain wound around the plurality of transmission sprockets, and the transmission chain engaging with each of the plurality of transmission sprockets; the motor is connected to one of the transmission sprockets to drive the plurality of transmission rollers to rotate synchronously via the transmission chain.

[0031] It should be noted that there is a gap between the bottom of the spacer 400 and the surface of the conveyor roller 350 to prevent interference between the spacer 400 and the conveyor roller 350.

[0032] like Figure 1 As shown, in some embodiments, the preheating chamber 300 is provided with multiple observation windows 340, each corresponding to a heating station 330. Operators can view the position of the shelves 100, the appearance of cable accessories, and the heating status of each heating station 330 in real time through the observation windows 340 without opening the chamber, facilitating timely detection of problems such as jamming, deformation, or abnormal temperature rise. The observation windows 340 are double-layered glass. The preheating chamber 300 has multiple mounting openings, each corresponding to an observation window 340, with the double-layered glass positioned on the mounting opening.

[0033] In some embodiments, a temperature sensor is provided inside the insulation box 200 to obtain the temperature inside the insulation box 200 so as to monitor the temperature change inside the insulation box 200 in real time.

[0034] like Figure 1 As shown, in some embodiments, the insulated box 200 is provided with a plurality of rolling rollers 210, which are arranged on the bottom wall of the insulated box 200. When the shelf 100 is placed into or removed from the insulated box 200, the rolling of the plurality of rolling rollers 210 reduces the resistance to the movement of the shelf 100, making the shelf 100 easier and less strenuous to move, while reducing wear between the shelf 100 and the bottom of the box, thus extending the service life of the equipment.

[0035] In some embodiments, the insulated box 200 is provided with a pick-up and drop-off port, and a door is rotatably connected to the insulated box 200. The door is used to open or close the pick-up and drop-off port. Along the arrangement direction of the plurality of rolling rollers 210, the pick-up and drop-off port is located on one side of the insulated box 200.

[0036] A second aspect of the present invention provides a processing apparatus for cable accessories, including a forming mold and an energy-saving secondary forming mechanism for cable accessories according to any embodiment of the first aspect.

[0037] It is understood that the energy-saving secondary forming mechanism for cable accessories has the beneficial effects of the above embodiments, and the processing equipment for cable accessories has the corresponding beneficial effects of the above embodiments. The specific implementation method can be referred to the above embodiments, and will not be repeated in this application.

[0038] In some embodiments, the molding assembly also includes structures such as vulcanizing tanks in the prior art. The specific structure of the molding assembly is not particularly limited in the embodiments of the present invention. The molding die is a mold in the prior art, and the cable accessory is molded in one step using the molding die.

[0039] The third embodiment of the present invention provides a secondary molding method for cable accessories, such as... Figure 2 As shown, it includes: Step S100: Place the one-time molded cable accessory into the shelf 100 inside the insulation box 200, and insulate the cable accessory through the insulation box 200; Placing the one-time molded cable accessories into the shelf 100 inside the insulation box 200 for insulation can effectively slow down the cooling rate of the cable accessories and avoid internal stress or micro cracks caused by rapid cooling.

[0040] Step S200: The high-temperature exhaust gas from the secondary molding process is introduced into the discharge end 320 of the preheating chamber 300; The preheating chamber 300 is heated by the high-temperature exhaust gas from the secondary molding process to make full use of the residual heat from the secondary molding process.

[0041] Step S300: Place the shelf 100 inside the insulated box 200 into the preheating box 300; The drive unit drives the shelf 100 to move in the direction from the feeding end 310 to the discharging end 320, so that the shelf 100 passes through each heating station 330 in sequence. Step S400: Remove the shelf 100 from the discharge end 320 and place it in the oven 600 for heating.

[0042] High-temperature exhaust gas flows from the discharge end 320 to the feed end 310, creating a temperature gradient between the multiple heating stations 330. The drive component moves the shelf 100 from the feed end 310 to the discharge end 320, allowing the shelf 100 to pass through each heating station 330 in the preheating chamber 300 in sequence. This achieves a step-by-step, gradual preheating process, preventing the rubber inserts from delaminating and detaching due to excessively rapid heating, thus avoiding waste.

[0043] In some embodiments, the shelf 100 is provided with multiple placement positions; removing the shelf 100 from the insulated box 200 and placing the shelf 100 into the preheating box 300 through the feeding end 310 includes: If multiple placement positions contain cable accessories, remove the shelf 100 from the insulation box 200 and place the shelf 100 into the preheating box 300 through the feeding end 310.

[0044] When multiple placement positions are set on the shelf 100, and cable accessories are placed in all placement positions, removing the shelf 100 from the insulation box 200 and sending it into the preheating box 300 can ensure that the batch capacity in the preheating box 300 is maximized each time, making full use of the heating space and capacity of the equipment, and avoiding energy waste and equipment idleness caused by partial loading.

[0045] After preheating, the shelf 100 at the discharge end 320 is taken out and placed directly into the oven 600 for heating. This ensures that the preheating process and the forming heating process are closely linked in time, reducing heat loss during intermediate transfer and ensuring that the starting temperature of the accessories when they enter the oven 600 is at a high and stable level. This shortens the secondary heating time of the oven 600, improves production efficiency, and reduces energy consumption.

[0046] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined in this application.

Claims

1. An energy-saving secondary forming mechanism for cable accessories, characterized in that, include: Shelves for accommodating multiple cable accessories; An insulated box is used to hold the shelf in order to insulate the cable accessories after they have been molded in one piece. A preheating assembly includes a preheating chamber, a driving component, and multiple spacers. The preheating chamber has an inlet and an outlet opposite to each other, and the outlet is provided with an air inlet. The preheating chamber contains multiple heating stations arranged in a row. Multiple spacers are spaced apart within the preheating chamber. A spacer is positioned between adjacent heating stations. The driving component drives a shelf to move from the inlet to the outlet, so that the shelf passes sequentially through each heating station. A molding assembly includes an oven having an air outlet and an air inlet connected together; the oven is used to heat the cable accessory transferred from the discharge end to the molding assembly.

2. The energy-saving secondary forming mechanism for cable accessories according to claim 1, characterized in that, The spacer is rotatably connected to the top wall of the preheating chamber.

3. The energy-saving secondary forming mechanism for cable accessories according to claim 2, characterized in that, The preheating assembly also includes multiple limiting blocks, which are configured one-to-one with the spacers; the limiting blocks are disposed on the top wall of the preheating chamber, and the limiting blocks are located on the side of the corresponding spacer closer to the feed end.

4. The energy-saving secondary forming mechanism for cable accessories according to claim 1, characterized in that, The driving component includes multiple conveying rollers arranged inside the preheating chamber; the multiple conveying rollers rotate to drive the shelf to move inside the preheating chamber.

5. The energy-saving secondary forming mechanism for cable accessories according to claim 1, characterized in that, The preheating chamber is equipped with multiple observation windows, and each observation window corresponds to a heating station.

6. The energy-saving secondary forming mechanism for cable accessories according to any one of claims 1 to 5, characterized in that, A temperature sensor is installed inside the insulation box to obtain the temperature inside the insulation box.

7. The energy-saving secondary forming mechanism for cable accessories according to any one of claims 1 to 5, characterized in that, The insulation box is equipped with multiple rolling rollers, which are arranged on the bottom wall of the insulation box.

8. Equipment for processing cable accessories, characterized in that, It includes a molding die and an energy-saving secondary molding mechanism for cable accessories as described in any one of claims 1 to 7.

9. A secondary forming method for cable accessories, applied to the energy-saving secondary forming mechanism for cable accessories according to any one of claims 1 to 7 or the processing equipment for cable accessories according to claim 8, characterized in that, include: The cable accessories, after being formed in one piece, are placed on a shelf inside an insulated box, and the cable accessories are insulated using the insulated box. The high-temperature exhaust gas from the secondary molding process is introduced into the discharge end of the preheating chamber. Place the shelf inside the insulated box into the preheating box; The drive unit drives the shelf to move from the feeding end to the discharging end, so that the shelf passes through each heating station in sequence; Remove the shelf from the discharge end and place it in the oven for heating.

10. The secondary molding method for cable accessories according to claim 9, characterized in that, The shelf is provided with multiple placement positions; the step of removing the shelf from the insulated box and placing the shelf into the preheating box through the feeding end includes: If multiple of the placement positions contain cable accessories, the shelf inside the insulation box is removed and placed into the preheating box from the feeding end.

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