Interlayer injection device

Abstract

The utility model relates to the field of injection molding equipment, and discloses an interlayer injection device which comprises a fixed mold plate provided with a forming mold, a main injection part and an auxiliary injection part, a main injection nozzle of the main injection part directly faces a pouring gate of the forming mold and can be in butt joint with or be far away from the pouring gate, and the auxiliary injection part vertically slides on a support on the fixed mold plate. An auxiliary injection nozzle of the auxiliary injection part can be in butt joint with the main injection nozzle or be far away from the main injection nozzle in the lifting process, and adjusting structures are arranged among the fixed mold plate, the main injection part and the auxiliary injection part; the adjusting structure comprises a main X-axis fine adjustment mechanism and a main Z-axis fine adjustment mechanism which are respectively used for realizing fine adjustment of the main injection part along an X axis perpendicular to the injection direction of the main injection nozzle and a Z axis in the vertical direction, and an auxiliary X-axis fine adjustment mechanism, an auxiliary Y-axis fine adjustment mechanism and an auxiliary Z-axis fine adjustment mechanism which are respectively used for realizing fine adjustment of the auxiliary injection part along the X axis, the Y axis and the Z axis; according to the interlayer injection device, the positions of the main nozzle and the auxiliary nozzle can be finely adjusted, so that the sprue, the main nozzle and the auxiliary nozzle are kept concentric.

Description

TECHNICAL FIELD

[0001] The utility model relates to injection equipment technical field especially relates to a sandwich injection device. BACKGROUND

[0002] The existing sandwich injection molding machine is mainly used for mixing recycled material and high-quality skin layer material to make products, so as to achieve the purpose of using recycled materials. Compared with the traditional injection molding machine, the sandwich injection molding machine can form the product with different materials in the inner and outer layers at one time. It can reduce the cost by using recycled material as the core material, increase the product performance by using high-quality material with special surface properties, or reduce the residual stress by properly matching the skin layer material and the core material, thereby improving the product strength.

[0003] The Chinese patent with publication number CN214725896U discloses a sandwich injection molding equipment, which includes a molding die, a main injection station, and at least one auxiliary injection station. The molding die has a cavity and a gate. The injection station has an injection station material pipe, a main injection displacement mechanism that drives the main injection station material pipe to approach or move away from the molding die, a main injection nozzle arranged at the front end of the main injection station material pipe, and a main flow channel arranged in the injection station material pipe and connected to the main injection nozzle. The auxiliary injection station also has an auxiliary injection displacement mechanism and an auxiliary injection nozzle arranged at the front end of the auxiliary injection station material pipe. The auxiliary injection nozzle is connected to the main injection nozzle and injects the material in the auxiliary injection station material pipe into the main flow channel. During injection, the auxiliary injection nozzle is first moved to connect to the main injection nozzle and injects the material in the auxiliary injection station material pipe into the main flow channel. Then, the auxiliary injection nozzle moves away from the main injection nozzle, and the main injection nozzle moves to connect to the gate. When the main injection station injects into the cavity, it first pushes the material in the main flow channel into the cavity and then pushes the material in the main injection station into the cavity. This realizes the pre-arrangement of the materials in the main flow channel before they enter the cavity in sequence. The outer surface of the material that enters the cavity first starts to solidify, and the material that enters the cavity later pushes away the material that enters the cavity first, forming the outer layer of the molded part. The material that enters the cavity later forms the inner layer of the molded part, achieving one-time molding of the sandwich injection molded part.

[0004] The above-mentioned sandwich injection molding equipment requires the auxiliary injection nozzle, the main injection nozzle, and the gate of the molding die to be concentric to ensure accurate connection during injection. However, during actual production and installation, size errors and installation errors may occur in each component, making it difficult to ensure the concentricity of the three components. Therefore, it is necessary to set a structure to adjust the concentricity. SUMMARY

[0005] The utility model provides a sandwich injection device that can adjust the concentricity of the gate, the auxiliary injection nozzle, and the main injection nozzle to overcome the shortcomings of the existing sandwich injection device, which is difficult to ensure the concentricity of the gate, the auxiliary injection nozzle, and the main injection nozzle due to production and assembly errors during production and assembly.

[0006] To solve the above technical problems, the utility model discloses the following technical scheme:

[0007] A kind of sandwich injection device, including the fixed mold plate of installation forming mould, main injection component and vice injection component, the main nozzle of main injection component is directly opposite the gate of forming mould and can be docked or away from gate, vice injection component vertically slips on the support on fixed mold plate, the vice nozzle of vice injection component can be docked with main nozzle or away from main nozzle in the lifting process, adjusting structure for adjusting the concentricity of gate, main nozzle and vice nozzle is provided between fixed mold plate, main injection component and vice injection component, adjusting structure includes main X-axis fine adjustment mechanism and main Z-axis fine adjustment mechanism respectively realizing the fine adjustment of main injection component along X axis and Z axis in vertical main nozzle injection direction, and vice X-axis fine adjustment mechanism, vice Y-axis fine adjustment mechanism and vice Z-axis fine adjustment mechanism respectively realizing the fine adjustment of vice injection component along X axis, Y axis and Z axis.

[0008] With the above scheme, adjusting structure for adjusting concentricity is additionally provided, and in the adjusting structure, when fixed mold plate is fixed and does not move, the maximum stroke of main nozzle injection is unchanged, so that main nozzle only needs to be fine adjusted along X axis and Z axis to ensure that main nozzle and gate maintain concentricity, and the concentricity of vice nozzle and gate can be realized by the joint adjustment of vice X-axis fine adjustment mechanism, vice Y-axis fine adjustment mechanism and vice Z-axis fine adjustment mechanism, and vice nozzle and gate maintain concentricity to accurately maintain concentricity with main nozzle, and after adjusting structure is provided, main nozzle, vice nozzle and the gate of forming mould can always maintain concentricity.

[0009] As a preferred, main X-axis fine adjustment mechanism, vice X-axis fine adjustment mechanism and vice Y-axis fine adjustment mechanism are consistent in structure, and each include two parallel and fixedly arranged fine adjustment blocks and adjusting locking bolts screw-connected on each fine adjustment block, and the threaded segments of the adjusting locking bolts on the two fine adjustment blocks are oppositely arranged and synchronously abut against the two sides of the component to be adjusted.

[0010] With the above scheme, the component to be adjusted (support or main sliding seat) can be fine adjusted along X axis or Y axis by the back-and-forth pressing adjustment of the adjusting bolts on the two sides of the fine adjustment block.

[0011] As a preferred, main Z-axis fine adjustment mechanism includes height-adjusting bolt with central hole and locking bolt inserted in the central hole, the height-adjusting bolt is rotationally arranged on main injection component, main injection component is installed on main sliding seat that slides along the injection direction of main nozzle, main sliding seat is provided with height-adjusting thread groove for the rotation of height-adjusting bolt, locking thread groove for the rotation of locking bolt is arranged downward at the bottom of height-adjusting thread groove, and the central hole and locking bolt have adjusting interval for the fine adjustment of main injection component along X axis.

[0012] The above scheme is adopted, the existence of the adjusting interval limits the adjusting range while ensuring the fine adjustment of the main injection component along the X axis. When adjusting, the locking bolt is loosened first, then the vertical height of the adjusting bolt is adjusted. When the adjusting bolt is pushed upward, the main injection component is raised. When the adjusting bolt is pushed downward, the main injection component is lowered. After the height is adjusted, the locking bolt is locked.

[0013] As a preferred, the auxiliary Z-axis fine adjustment mechanism comprises a limiting block fixed on the support and used for limiting the maximum downward stroke of the auxiliary injection component, a buffer adjusting block located above the limiting block and used for supporting the auxiliary injection component, and an adjusting assembly arranged between the buffer adjusting block and the limiting block and used for adjusting the vertical height of the buffer adjusting block.

[0014] As a preferred, the adjusting assembly comprises an adjusting bolt and a connecting bolt. The adjusting bolt is screwed on the limiting block from bottom to top and abuts against the lower end surface of the buffer adjusting block. The connecting bolt is screwed on the buffer adjusting block after penetrating the limiting block from bottom to top.

[0015] The above scheme is adopted. When adjusting, the connecting bolt is loosened first, then the height of the buffer adjusting block is adjusted by screwing the adjusting bolt. After adjusting, the connecting bolt is connected with the buffer adjusting block to fix the buffer adjusting block and the limiting block.

[0016] As a preferred, a positioning pin is arranged between the limiting block and the support to increase the connecting strength of the two.

[0017] The above scheme is adopted. The design of the positioning pin can increase the resistance of the limiting block and reduce the probability of torsional deformation of the limiting block.

[0018] As a preferred, a supporting assembly is arranged between the fixed die plate and the auxiliary nozzle and used for supporting the auxiliary nozzle to resist the impact force generated when the main nozzle is docked with the auxiliary nozzle.

[0019] As a preferred, the supporting assembly comprises a sliding plate fixed on the fixed die plate and extending along the lifting direction of the auxiliary nozzle, and a supporting pad plate fixed on the auxiliary nozzle and slidingly matched with the sliding plate.

[0020] The above scheme is adopted. The sliding matching of the supporting pad plate and the sliding plate can increase the resistance of the auxiliary nozzle along the injection direction of the main nozzle and ensure the smoothness of the lifting of the auxiliary nozzle.

[0021] As a preferred, a heat insulation plate is arranged between the supporting pad plate and the auxiliary nozzle and used for heat insulation.

[0022] The above scheme is adopted. The heat insulation plate can insulate most of the heat of the auxiliary nozzle and prevent the supporting pad plate and the sliding plate from being thermally deformed.

[0023] As a preferred, a sliding gasket slidingly matched with the sliding plate is fixed on the side of the supporting pad plate away from the heat insulation plate.

[0024] With the above scheme, the slip gasket is used for friction fit with the slide plate, and the slip gasket is a consumable and is easy to replace.

[0025] The utility model discloses a remarkable technical effect has added the adjusting structure for adjusting concentricity, in the adjusting structure, the fixed condition of fixed plate, the maximum stroke of main injection nozzle injection is invariable, therefore, main injection nozzle only needs to guarantee that main injection nozzle and the gate keep concentricity along with X axle and Z axle fine adjustment, and the concentricity of vice injection nozzle and the gate can be realized through the common adjustment of vice X axle fine adjustment mechanism, vice Y axle fine adjustment mechanism and vice Z axle fine adjustment mechanism, and vice injection nozzle and the gate keep concentricity, can accurately keep concentricity with main injection nozzle, after setting adjusting structure, can guarantee that main injection nozzle, vice injection nozzle and the gate of forming mould keep concentric state all the time. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the axonometric view of a sandwich injection device of the embodiment; Figure 1 ;

[0027] Figure 2 is the enlarged view of A of Figure 1 ;

[0028] Figure 3 is the enlarged view of B of Figure 1 ;

[0029] Figure 4 is the enlarged view of C of Figure 1 ;

[0030] Figure 5 is the axonometric view of a sandwich injection device of the embodiment; Figure 2 ;

[0031] Figure 6 is the enlarged view of D of Figure 5 ;

[0032] Figure 7 is the enlarged view of E of Figure 5 .

[0033] The part names referred to by the numbers in the above drawings are as follows: 1, fixed mold plate; 2, main injection part; 201, main pre-plasticizing part; 202, main injection part; 203, main plasticizing part; 2031, main injection nozzle; 204, main sliding seat; 205, main whole-moving oil cylinder; 3, auxiliary injection part; 301, auxiliary pre-plasticizing part; 302, auxiliary injection part; 303, auxiliary plasticizing part; 3031, auxiliary injection nozzle; 304, auxiliary whole-moving oil cylinder; 4, support; 5, pressing bolt; 6, first gasket; 7, fine adjustment block; 8, adjusting locking bolt; 9, sliding plate; 10, supporting gasket plate; 11, sliding gasket; 12, heat insulation plate; 13, limiting block; 14, fastening bolt; 15, positioning pin; 16, buffer adjusting block; 17, adjusting bolt; 18, connecting bolt; 19, limiting bolt; 20, height adjusting bolt; 21, second gasket; 22, locking bolt. DETAILED DESCRIPTION

[0034] The utility model will be described in further detail below in combination with the drawings and examples.

[0035] A sandwich injection device, referring to Figure 1 and Figure 5 , comprises a fixed mold plate 1 provided with a forming mold having a gate communicated with an internal cavity, a main injection part 2 and an auxiliary injection part 3, the main injection part 2 comprises a main pre-plasticizing part 201, a main injection part 202 and a main plasticizing part 203 in sequence towards the direction close to the fixed mold plate 1, the main plasticizing part 203 is provided with a main injection nozzle 2031 at the end, the main injection part 2 is installed on a main sliding seat 204, the main sliding seat 204 is guided and slid along the injection direction of the main injection nozzle 2031 through a guide rail sliding block, the whole movement of the main injection part 2 is controlled by a main whole-moving oil cylinder 205, the two ends of the main whole-moving oil cylinder 205 are fixedly connected with the fixed mold plate 1 and the main injection part 202 respectively; a support 4 is vertically fixed on the upper end face of the fixed mold plate 1, the auxiliary injection part 3 is assembled on the side of the main injection part 2 of the support 4, the auxiliary injection part 3 is vertically guided and slid on the support 4 through a guide rail sliding block, the auxiliary injection part 3 comprises an auxiliary pre-plasticizing part 301, an auxiliary injection part 302 and an auxiliary plasticizing part 303 in sequence from top to bottom, the auxiliary plasticizing part 303 is provided with an auxiliary injection nozzle 3031 at the end, the auxiliary injection nozzle 3031 is a spring nozzle, and the above is the prior art.

[0036] In combination with Figures 1 to 7 , an adjusting structure for adjusting the concentricities of the gate, the main injection nozzle 2031 and the auxiliary injection nozzle 3031 is arranged between the fixed mold plate 1, the main injection part 2 and the auxiliary injection part 3.

[0037] The adjusting structure comprises a main X-axis fine adjustment mechanism and a main Z-axis fine adjustment mechanism for respectively realizing fine adjustment of the main injection component 2 along an X-axis perpendicular to the main injection nozzle 2031 injection direction and a Z-axis vertical direction, and a sub X-axis fine adjustment mechanism, a sub Y-axis fine adjustment mechanism and a sub Z-axis fine adjustment mechanism for respectively realizing fine adjustment of the sub injection component 3 along the X-axis perpendicular to the main injection nozzle 2031 injection direction, along a Y-axis perpendicular to the main injection nozzle 2031 injection direction and along the Z-axis vertical direction.

[0038] In combination Figure 2 , Figure 6 and Figure 7 , the main X-axis fine adjustment mechanism, the sub X-axis fine adjustment mechanism and the sub Y-axis fine adjustment mechanism have the same structure, each comprising two parallel and fixedly arranged fine adjustment blocks 7 and adjusting locking bolts 8 screw-coupled on each fine adjustment block 7, and taking the sub X-axis fine adjustment mechanism as an example, the two fine adjustment blocks 7 are fixed on the two sides of the support 4, and the adjusting locking bolts 8 are in abutting engagement with the two side walls of the support 4 after adjustment.

[0039] The support 4 is tightly fitted with the upper end surface of the fixed mold plate 1 through a plurality of groups of pressing bolts 5, and in order to realize fine adjustment of the support 4 along the X-axis and the Y-axis, a slot hole is formed on the support 4 for the pressing bolt 5 to pass through, the hole diameter of the slot hole is greater than the stud diameter of the pressing bolt 5, and there is an adjusting interval between the slot hole and the stud for fine adjustment of the support 4 in the front and back and left and right directions, and a first gasket 6 is fitted on the support 4 and can be passed through by the pressing bolt and has a diameter greater than that of the slot hole, the head of the pressing bolt 5 is pressed on the first gasket 6 to realize the limiting of the support 4 and the fixed mold plate 1 in the vertical direction, and the sub X-axis fine adjustment mechanism and the sub Y-axis fine adjustment mechanism limit the horizontal displacement of the support 4 after fine adjustment.

[0040] Referring to Figure 6 , in the sub Y-axis fine adjustment mechanism, after the fine adjustment block 7 is fixed with the fixed mold plate 1, a limiting bolt 19 is further fitted between the fine adjustment block 7 and the support 4, the limiting bolt 19 is screw-coupled with the support 4 after passing through the fine adjustment block 7 until the bolt head is pressed against the fine adjustment block 7.

[0041] The whole moving of the sub injection seat is controlled by the sub whole moving oil cylinder 304, the cylinder body of which is fixedly connected with the sub injection part 302 and the piston rod thereof is vertically downward and the end thereof is fixedly connected with the upper end surface of the fixed mold plate 1. The sub Z-axis fine adjustment mechanism comprises a limiting block 13 fixed on the support 4 and used for limiting the maximum downward stroke of the sub injection part 3, a buffer adjusting block 16 located above the limiting block 13 and used for supporting the sub injection part 3, and an adjusting assembly arranged between the buffer adjusting block 16 and the limiting block 13 and used for adjusting the vertical height of the buffer adjusting block 16, the adjusting assembly comprising an adjusting bolt 17 screwed on the limiting block 13 and having an end opposite to the downward end of the sub injection part 3, and two connecting bolts 18 located on both sides of the adjusting bolt 17 and screwed with the buffer adjusting block 16 after passing through the through holes in the limiting block 13 until the heads of the connecting bolts 18 abut against the limiting block 13. In order to increase the stability of the installation of the limiting block 13, one end of the limiting block 13 is fixed to the side wall of the support 4 by four fastening bolts 14 and the other end extends out of the support 4 and is located below the sub injection part 3, the adjusting bolt 17 and the connecting bolts 18 are arranged on the extended section of the limiting block 13, and two positioning pins 15 for increasing the resistance to torsional deformation of the limiting block 13 are arranged between the limiting block 13 and the support 4.

[0042] The main Z-axis fine adjustment mechanism comprises an adjusting bolt 20 with a central hole and a locking bolt 22 inserted into the central hole, the adjusting bolt 20 is rotationally connected to the main injection part 2 (the adjusting bolt 20 cannot be separated from the main injection part 2), the main sliding seat 204 is provided with an adjusting thread groove for the rotation of the adjusting bolt 20, the bottom of the adjusting thread groove is provided with a locking thread groove for the rotation of the locking bolt 22, the central hole and the locking bolt 22 have an adjusting interval for the fine adjustment of the main injection part 2 along the X-axis, when the adjusting locking bolt 8 in the main Z-axis fine adjustment mechanism abuts against the main injection part 2, the main injection part 2 is fine adjusted within the adjusting interval, and the second washer 21 with a hole diameter larger than the central hole and capable of abutting against the head of the locking bolt 22 is arranged on the upper end of the adjusting bolt 20.

[0043] The support assembly for supporting the sub nozzle 3031 against the impact force generated when the main nozzle 2031 is butted against the sub nozzle 3031 is arranged between the fixed mold plate 1 and the sub nozzle 3031, the support assembly comprising a sliding plate 9 fixed to the fixed mold plate 1 and extending along the lifting direction of the sub nozzle 3031, and a support pad 10 fixed to the sub nozzle 3031 and slidably matched with the sliding plate 9, the support pad 10 and the sub nozzle 3031 are fixedly provided with a heat insulation plate 12 for heat insulation, the side of the support pad 10 away from the heat insulation plate 12 is fixedly provided with a sliding gasket 11 slidably matched with the sliding plate 9, and the sliding gasket is a copper gasket.

[0044] The injection process of the sandwich injection device is not improved, and will not be described here again, in the scheme, the adjusting structure for adjusting the concentricity of the gate, the main nozzle 2031 and the auxiliary nozzle 3031 is additionally arranged, the center positioning of the main nozzle 2031 and the gate is realized through the fine adjustment of the main injection component 2 along the X-axis and Y-axis directions, the center positioning of the auxiliary nozzle 3031 and the main nozzle 2031 is realized through the fine adjustment of the auxiliary injection component 3 along the X-axis, Y-axis and Z-axis directions, and then the center positioning of the gate, the main nozzle 2031 and the auxiliary nozzle 3031 is realized; the supporting assembly is additionally arranged, the deformation resistance of the auxiliary nozzle 3031 is increased, and it is ensured that the auxiliary nozzle 3031 can be accurately docked with the main nozzle 2031 after adjustment.

[0045] The preferred embodiments of the utility model are described above, the protection scope of the utility model is not only limited to the above-mentioned embodiments, and all technical schemes under the utility model idea belong to the protection scope of the utility model. It should be noted that for ordinary skilled people in the art, some improvements and decorations without departing from the principle of the utility model are also regarded as the protection scope of the utility model.

Claims

1. A sandwich injection device, comprising a fixed mold plate (1) on which a forming mold is mounted, a main injection part (2) and a sub-injection part (3), a main nozzle (2031) of the main injection part (2) is opposite to a gate of the forming mold and can be docked or away from the gate, the sub-injection part (3) vertically slides on a support (4) on the fixed mold plate (1), a sub-nozzle (3031) of the sub-injection part (3) can be docked with or away from the main nozzle (2031) in the lifting process, characterized in that: The adjusting structure is arranged between the fixed mold plate (1), the main injection part (2) and the auxiliary injection part (3) and is used for adjusting the concentricity of the three of the gate, the main nozzle (2031) and the auxiliary nozzle (3031), and the adjusting structure comprises a main X-axis fine adjustment mechanism and a main Z-axis fine adjustment mechanism which respectively realize the fine adjustment of the main injection part (2) along the X-axis and the Z-axis in the vertical direction of the main nozzle (2031), and an auxiliary X-axis fine adjustment mechanism, an auxiliary Y-axis fine adjustment mechanism and an auxiliary Z-axis fine adjustment mechanism which respectively realize the fine adjustment of the auxiliary injection part (3) along the X-axis, the Y-axis and the Z-axis. ​ 2. A sandwich injection device according to claim 1, characterized in that: The main X-axis fine adjustment mechanism, the auxiliary X-axis fine adjustment mechanism and the auxiliary Y-axis fine adjustment mechanism are consistent in structure and each comprises two parallel and fixed adjusting blocks (7) and adjusting locking bolts (8) which are screwed on each adjusting block (7), and the threaded segments of the adjusting locking bolts (8) on the two adjusting blocks (7) are oppositely arranged and are in synchronous abutting cooperation with the two sides of the part to be adjusted.

3. A sandwiched injection device according to claim 2, characterized in that: The main Z-axis fine adjustment mechanism comprises a height adjusting bolt (20) with a central hole and a locking bolt (22) inserted in the central hole, the height adjusting bolt (20) is rotationally arranged on the main injection part (2), the main injection part (2) is installed on a main sliding seat (204) which slides along the injection direction of the main nozzle (2031), the main sliding seat (204) is provided with a height adjusting threaded groove for the rotation of the height adjusting bolt (20), and a locking threaded groove for the rotation of the locking bolt (22) is arranged downward at the bottom of the height adjusting threaded groove, and the central hole and the locking bolt (22) have an adjusting interval for the fine adjustment of the main injection part (2) along the X-axis.

4. A sandwich injection device according to claim 2, characterized in that: The auxiliary Z-axis fine adjustment mechanism comprises a limiting block (13) fixed on the support (4) and used for limiting the maximum downward stroke of the auxiliary injection part (3), a buffer adjusting block (16) located above the limiting block (13) and used for supporting the auxiliary injection part (3), and an adjusting assembly arranged between the buffer adjusting block (16) and the limiting block (13) and used for adjusting the vertical height of the buffer adjusting block (16).

5. A sandwiched injection device according to claim 4, characterized in that: The adjusting assembly comprises an adjusting bolt (17) and a connecting bolt (18), the adjusting bolt (17) is screwed on the limiting block (13) from bottom to top and is in abutting cooperation with the lower end surface of the buffer adjusting block (16), and the connecting bolt (18) is screwed on the buffer adjusting block (16) after penetrating through the limiting block (13) from bottom to top.

6. A sandwich injection device according to claim 4, characterized in that: The limiting block (13) and the support (4) are inserted with a positioning pin (15) for increasing the connection strength of the two.

7. A sandwiched injection device according to claim 1, characterized in that: A support assembly is arranged between the fixed mold plate (1) and the auxiliary nozzle (3031) and is used for supporting the auxiliary nozzle (3031) to resist the impact force generated when the main nozzle (2031) is butted against the auxiliary nozzle (3031).

8. A sandwiched injection device according to claim 7, characterized in that: The support assembly comprises a sliding plate (9) fixed on the fixed mold plate (1) and extending along the lifting direction of the auxiliary nozzle (3031), and a support backing plate (10) fixed on the auxiliary nozzle (3031) and in sliding cooperation with the sliding plate (9).

9. A sandwiched injection device according to claim 8, characterized in that: A heat insulation plate (12) is arranged between the support backing plate (10) and the auxiliary nozzle (3031) and is used for heat insulation.

10. A sandwiched injection device according to claim 8, characterized in that: The support backing plate (10) is fixed with a sliding backing piece (11) which is in sliding cooperation with the sliding plate (9) on the side away from the heat insulation plate (12).

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