JP2021194912A - Injection device - Google Patents

Abstract

To provide an injection device that is further suitable for a temperature change of a resin material.SOLUTION: A heating cylinder 12 comprises a preheating unit 21, a heating unit 22, and a heat insulating unit 23 from a base to a tip. The preheating unit 21, the heating unit 22, and the heat insulating unit 23 are composed of band heaters. In the heating unit 22 shown in FIG. (b), a heat transfer amount to the heating cylinder 12 is q1. In the preheating unit 21 shown in FIG. (c), a band heater is configured such that a heat transfer amount q4 to the heating cylinder 12 is larger than the heat transfer amount q1. In the heat insulating unit 23 shown in FIG. (a), a band heater is configured such that a heat transfer amount q6 to the heating cylinder 12 is smaller than the heat transfer amount q1.SELECTED DRAWING: Figure 9

Description

The present invention relates to an injection device having a heating mechanism in a heating cylinder. In this document, aluminum includes an aluminum alloy.

Various injection devices for injecting a molten resin material from a nozzle at the tip are known (see, for example, Patent Document 1 (FIG. 1)).

Patent Document 1 will be described with reference to the following figure.
FIG. 14 is a diagram illustrating the structure of a conventional injection device.
As shown in FIG. 14, the conventional injection device 100 includes a heating cylinder 102 having a nozzle 101 at the tip thereof, and a screw 103 housed in the heating cylinder 102 so as to be rotatable and axially movable. ..

Four temperature sensors 104 to 107 are embedded in the heating cylinder 102 between the hopper 104 on the base side and the nozzle 101 at the tip, and heating mechanisms 111 to 114 are arranged corresponding to the temperature sensors 104 to 107, respectively. There is.

The heating mechanisms 111 to 114 each include a band heater 115 wound around the heating cylinder 102, a ventilation layer 116 wound around the band heater 115, and a heat insulating layer 117 wound around the ventilation layer 116.
The output of the band heater 115 is controlled so that the temperature sensor 104 reaches the set temperature.
Similarly, the output of each band heater 115 is controlled so that the temperature sensors 105 to 107 reach the set temperature.

Conventionally, heating mechanisms 111 to 114 have been arranged in the axial direction (longitudinal direction) of the heating cylinder 102 to control the temperature of the heating cylinder 102. However, the heating mechanism 111, the heating mechanism 112, the heating mechanism 113, and the heating mechanism have been performed. 114 had the same structure as each other.

If the structure is the same, the procurement cost of parts can be reduced and there is no concern about misassembly. On the other hand, considering the temperature change of the resin material, there is room for improvement.

Japanese Patent No. 6258250

An object of the present invention is to provide an injection device suitable for a temperature change of a resin material.

In order to solve the above problems, the present inventors have examined in detail the changes in the resin material.
First, at the base of the heating cylinder 102, the resin material is supplied to the heating cylinder 102 via the hopper 104 in the form of pellets. Since the pellets are lumps and the lumps are in point contact with each other, the heat supplied by the heating mechanism 114 is transferred from one lump to the next with a small heat transfer area. Therefore, it was found that the heat transfer efficiency of the heating mechanism 114 is low.

On the other hand, in the middle portion of the heating cylinder 102, the resin material is liquefied and the heat transfer area is increased. Therefore, it was found that the heating mechanisms 112 and 113 have high heat transfer efficiency.
Further, at the tip of the heating cylinder 102, the resin material has reached a predetermined temperature, and heating is not required so much. Therefore, it was found that temperature control is important in the heating mechanism 111.
Based on the above findings, we improved the structure of the injection device and were able to solve the problem.

That is, the invention according to claim 1 comprises a heating cylinder having a nozzle at the tip, a screw housed in the heating cylinder so as to be rotatable and axially movable, and a heating mechanism wound around the heating cylinder. In the device
The heating mechanism is arranged at a preheating portion arranged at the base of the heating cylinder, a heating portion arranged closer to the tip of the heating cylinder than the preheating portion, and a heating portion closer to the tip of the heating cylinder than the heating portion. It has a heat insulating part and
The preheating portion is configured to have higher heating performance to the heating cylinder than the heating portion.
The heat insulating portion is characterized in that the heating performance of the heating cylinder is lower than that of the heating portion.

The invention according to claim 2 is the injection device according to claim 1.
The heating portion covers the inner case wound around the heating cylinder, the inner electric insulating material covering the outer peripheral surface of the inner case, the heating element covering the outer peripheral surface of the inner electric insulating material, and the outer peripheral surface of the heating element. It consists of an outer electrical insulating material, an outer case that covers the outer peripheral surface of the outer electrical insulating material, and a band that covers the outer peripheral surface of the outer case.
The preheating section has the same structure as the heating section except that the outer electrical insulating material is thicker than the heating section.
The heat insulating portion is characterized in that at least one of the outer case and the band is made of a material having a high thermal conductivity with respect to the heating portion, and the other parts have the same configuration as the heating portion.

The invention according to claim 3 is the injection device according to claim 2.
The outer electrical insulating material of the preheating portion is characterized in that it is thickened by stacking the outer electrical insulating material of the heating portion.

The invention according to claim 4 is the injection device according to claim 1.
The heating portion covers the inner case wound around the heating cylinder, the inner electric insulating material covering the outer peripheral surface of the inner case, the heating element covering the outer peripheral surface of the inner electric insulating material, and the outer peripheral surface of the heating element. It consists of an outer electrical insulating material, an outer case that covers the outer peripheral surface of the outer electrical insulating material, and a band that covers the outer peripheral surface of the outer case.
The preheating section employs a heating element having a larger output per unit area than the heating section, and has the same configuration as the heating section except for the heating section.
The heat insulating unit is characterized in that a heating element having a smaller output per unit area than the heating unit is used, and the other parts have the same configuration as the heating unit.

The invention according to claim 5 is the injection device according to any one of claims 2 to 4.
The inner case, the inner electric insulating material, the heating element, the outer electric insulating material, the outer case and the band are each divided at at least one place, and the divided positions are set so that the heating cylinder can be seen from the outside. It is characterized by being aligned.

The invention according to claim 6 is the injection device according to claim 5.
The split in the heat insulating portion is characterized in that it is positioned directly above the heating cylinder.

The invention according to claim 7 is the injection device according to claim 5.
The split in the preheating portion is characterized in that it is positioned directly below the heating cylinder.

In the invention according to claim 1, since the preheating unit has a higher heating performance to the heating cylinder than the heating unit, the temperature of the pellet can be further increased.
Further, since the heat insulating portion has a lower heating performance to the heating cylinder than the heating portion, the resin material is not overheated and can be easily controlled to a desired temperature.
Therefore, according to claim 1, an injection device suitable for changing the temperature of the resin material is provided.

In the invention according to claim 2, the preheating part is made of a thick outer electric insulating material with respect to the heating part, and the heat insulating part is made of a material having high thermal conductivity at least one of the outer case and the band with respect to the heating part. did. That is, most of the components of the preheating section, the heating section, and the heat insulating section are common, and the ease of assembly is maintained while suppressing the procurement cost of parts.

In claim 3, the outer electric insulating material of the preheating part is a stack of the outer electric insulating material of the heating part. The outer electrical insulating material can be shared by the preheating section, the heating section, and the heat insulating section.

In claim 4, the heating element is different between the preheating unit, the heating unit, and the heat insulating unit. Since the other components are common, the procurement cost of parts can be suppressed and the management of parts becomes easy.

In claim 5, the inner case, the inner electric insulating material, the heating element, the outer electric insulating material, the outer case and the band are each divided at at least one place, and the divided positions are aligned so that the heating cylinder can be seen from the outside. Has been done. By aligning the split positions, the adhesion when tightening the band is improved, the heat transfer property can be improved, and energy saving can be achieved.

In the invention according to claim 6, the split in the heat insulating portion is positioned directly above the heating cylinder. Since convection heat transfer is maximized in the upward direction, heat is actively released to the atmosphere from the heat insulating part, and the temperature control performance of the heat insulating part is further enhanced.

In the invention according to claim 7, the split in the preheating section is positioned directly below the heating cylinder. Since convection heat transfer is minimized downward, almost no heat is released to the atmosphere due to the preheating section. As a result, the heating performance of the preheating section is further improved and energy can be saved.

It is a side view which shows the main part of the injection apparatus which concerns on this invention. It is a perspective view of a heating element. FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 and is a sectional view of a heating portion. It is an exploded view of the 4-4 line cross section of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. 1 and is a sectional view of a preheating portion. It is an exploded view of the 6-6 line cross section of FIG. FIG. 7 is a cross-sectional view taken along the line 7-7 of FIG. 1 and is a cross-sectional view of a heat insulating portion. It is an exploded view of the cross section of line 8-8 of FIG. (A) is an explanatory diagram of the operation of the heat insulating portion, (b) is an explanatory diagram of the operation of the heating portion, and (c) is an explanatory diagram of the operation of the preheating portion. (A) is a cross-sectional view of a modified example of the band, and (b) is a view taken along the line b of (a). (A)-(c) is a figure explaining the modification example of the heating element. (A) is a perspective view illustrating a further modification example of the heating element, (b) is a sectional view taken along line bb of (a), and (c) is a sectional view illustrating a comparative example. (A) is a diagram showing a preferable position for splitting the heat insulating portion, (b) is a diagram showing a preferable position for splitting the heating portion, and (c) is a diagram showing a preferred position for splitting the preheating portion. It is a figure explaining the structure of the conventional injection apparatus.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the injection device 10 is wound around a heating cylinder 12 having a nozzle 11 at its tip, a screw 13 rotatably and axially movable in the heating cylinder 12, and a heating cylinder 12. The heating mechanism 20 is provided, a drop port block 15 connected to the heating tube 12, and a hopper 17 attached to the drop port block 15. The pellet-shaped resin material is dropped from the pad 17 into the heating cylinder 12 through the drop port 16.

The heating mechanism 20 includes a preheating unit 21 arranged on the base side of the heating cylinder 12, a heating unit 22 arranged closer to the tip of the heating cylinder 12 than the preheating unit 21, and a heating cylinder 12 rather than the heating unit 22. It is composed of a heat insulating portion 23 arranged near the tip of the above. The structure of the heating element, which is one of the main components of the heating mechanism 20, will be described with reference to FIG.

As shown in FIG. 2, the heating element 25 is formed by winding a heating wire 27 around an insulating plate 26 in a spiral shape. The heating wire 27 is a bare wire. Therefore, the heating element 25 is covered from above and below with an electric insulating material described later.

Of the preheating unit 21, the heating unit 22, and the heat insulating unit 23, first, the configuration of the heating unit 22 will be described with reference to FIG.
As shown in FIG. 3, the heating unit 22 includes an inner case 31 wound around a heating cylinder (FIG. 1, reference numeral 12), an inner electric insulating material 32 covering the outer peripheral surface of the inner case 31, and the inner electric insulating material 32. A heating element 25 that covers the outer peripheral surface of the heating element 25, an outer electric insulating material 34 that covers the outer peripheral surface of the heating element 25, an outer case 35 that covers the outer peripheral surface of the outer electric insulating material 34, and an outer peripheral surface of the outer case 35. It consists of a band 36 to be covered.

The band 36 is preferably a one-piece band having one split, but may be a two-piece band having two splits. If it is a one-piece band or a two-piece band, the inner diameter of the band 36 can be reduced by tightening a bolt 37.

The split position of the inner case 31, the split position of the inner electrical insulating material 32, the split position of the heating element 25, the split position of the outer electrical insulating material 34, the split position of the outer case 35, and the split position of the band 36. match. Then, by tightening the bolt 37, the inner case 31 is brought into close contact with the heating cylinder 12, the inner electric insulating material 32 is brought into close contact with the inner case 31, the heating element 25 is brought into close contact with the inner electric insulating material 32, and the heating element 25 is brought into close contact with the heating element 25. The outer electric insulating material 34 can be brought into close contact with the outer electric insulating material 34, the outer case 35 can be brought into close contact with the outer case 35, and the band 36 can be brought into close contact with the outer case 35.

FIG. 4 is an exploded view of a cross section taken along line 4-4 of FIG.
As shown in FIG. 4, the heating unit 22 includes an inner case 31, an inner electric insulating material 32, a heating element 25, an outer electric insulating material 34, an outer case 35, and a band 36.
As the inner case 31, the outer case 35 and the band 36, a thin plate of stainless steel (for example, SUS304) that does not easily rust is suitable.
The inner electric insulating material 32 and the outer electric insulating material 34 are, for example, mica (mica) having a thickness of 0.4 mm. Two 0.2 mm thick mica may be stacked.

It is permissible to add the cooling jacket 38 shown by the imaginary line to the inside of the inner case 31. Refrigerant (water, air, etc.) is appropriately flowed through the cooling jacket 38.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 1, which is a sectional view of the preheating portion 21, and FIG. 6 is an exploded view of a sectional view taken along line 6-6 of FIG.
In FIG. 6, in the preheating section 21, the outer electric insulating material 34B is different from that in FIG. 4, but the other inner case 31, inner electric insulating material 32, heating element 25, outer case 35, and band 36 are shown in both form and material. Same as 4.

The outer electric insulating material 34B has a thickness (2 mm to 4 mm) 5 to 10 times that of the outer electric insulating material 34 shown in FIG. Preferably, the outer electric insulating material 34B is obtained by stacking 5 to 10 pieces of the outer electric insulating material 34 of FIG.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 1, which is a sectional view of the heat insulating portion 23, and FIG. 8 is an exploded view of the sectional view taken along line 8-8 of FIG.
In FIG. 8, in the heat insulating portion 23, the material of the outer case 35B is different from that of FIG. 4, but the other inner case 31, inner electric insulating material 32, heating element 25, outer electric insulating material 34, and band 36 are formed and made of materials. Both are the same as in FIG.
The outer case 35B is preferably an aluminum-plated carbon steel plate (aluminum-plated steel plate).

Table 1 shows the materials described above and the thermal conductivity λ (W / m · K) corresponding to these materials added to the heating unit, the preheating unit, and the heat insulating unit.

The thermal conductivity λ of mica is 0.5 (W / m · K), which is much smaller than the thermal conductivity λ16.3 (W / m · K) of SUS304. That is, mica has heat insulating performance in addition to electrical insulating performance.

In the preheating section, the thickness of the outer electrical insulating material was increased by 5 to 10 times with respect to the heating section. When the thickness is 5 times, the heat transfer amount is 1/5, and when the thickness is 10 times, the heat transfer amount is 1/10. That is, the preheated portion is insulated by the outer electric insulating material.

In the heat insulating part, an aluminum-plated steel plate is used for the outer case. The thermal conductivity λ of SUS304 is 16.3 (W / m · K), whereas the thermal conductivity λ of carbon steel is 54 (W / m · K), and the thermal conductivity λ of aluminum is Since it is 204 (W / m · K), the thermal conductivity λ of the aluminum-plated steel plate becomes sufficiently large. As a result, the amount of heat transferred from the outer case to the band increases, and the amount of heat dissipated from the band to the atmosphere increases.

Preferably, the band that was SUS304 is changed to an aluminum-plated steel plate as shown in the example of changing the heat insulating portion.
Alternatively, both the outer case and the band may be made of aluminum-plated steel plate. The amount of heat released from the band to the atmosphere is further increased.

The operation described in Table 1 will be described again with reference to the drawings.
FIG. 9A shows the action of the heat retaining section 23, FIG. 9B shows the action of the heating section 22, and FIG. 9C shows the action of the preheating section 21.
In the heating unit 22 shown in FIG. 9B, about half of the heat generated by the heating element 25 is transferred to the heating cylinder 12, and the remaining half of q2 is dissipated to the atmosphere.

On the other hand, in the preheating section 21 shown in FIG. 9C, the heat radiation q3 to the atmosphere becomes small due to the heat insulating action of the outer electric insulating material 34B, and most of the heat generated by the heating element 25 (heat transfer amount). q4 is transmitted to the heating cylinder 12.

Further, in the heat insulating portion 23 shown in FIG. 9A, since at least one of the outer case 35B and the band 36 is made of an aluminum-plated steel plate, the heat radiation q5 to the atmosphere increases by that amount, and the heating cylinder 12 The amount of heat transferred to q6 becomes smaller.
When the temperature of the heat insulating unit 23 exceeds a predetermined temperature, the heat radiation q5 is large, so that the temperature can be quickly lowered to the predetermined temperature. Therefore, the temperature control performance of the heat retaining unit 23 is significantly better than that of the heating unit 22 and the preheating unit 21.

Based on the heating unit 22, the preheating unit 21 is configured so that the heat transfer amount q4 is larger than the heat transfer amount q1, and the heat retention unit 23 is configured so that the heat transfer amount q6 is smaller than the heat transfer amount q1.
That is, the preheating unit 21 has a higher heating performance to the heating cylinder 12 than the heating unit 22, and the heat insulating unit 23 has a lower heating performance to the heating cylinder 12 than the heating unit 22.

An example of modification of the band 36 will be described with reference to FIG.
FIG. 10 (a) shows a cross-sectional view of the band 36B, and FIG. 10 (b) shows a view taken along the line b of FIG. 10 (a).
As shown in FIG. 10B, a cooling window 39 of an appropriate size is opened in the band 36B.

When the band 36 shown in FIG. 9A is replaced with the band 36B shown in FIG. 10B, the heat radiation q5 is further dissipated from the outer case 35 to the atmosphere without passing through the band 36B. To increase.
Therefore, in the structure of FIG. 10, SUS304 can be adopted as the material of the band 36B, and the choice of materials is increased.

Next, a modification of the heating element 25 will be described with reference to FIG.
FIG. 11B shows a heating element 25 used in the heating unit.
FIG. 11C shows a heating element 25 used in the preheating section. In this heating element 25, the output per unit area is increased by winding the heating wire 27 tightly as compared with the heating element 25 in the heating unit.
FIG. 11A shows a heating element 25 used in the heat insulating unit. In this heating element 25, the output per unit area is reduced by roughly winding the heating wire 27 as compared with the heating element 25 in the heating unit.

Table 2 shows an example in which such a heating element 25 is applied to a heating unit, a preheating unit, and a heat insulating unit.

In the heating unit, the preheating unit, and the heat insulating unit, the inner case, the inner electric insulating material, the outer electric insulating material, the outer case, and the band are common, and the thermal conductivity is common.
Based on the heating element of the heating section, the output of the heating element of the preheating section is large and the output of the heating element of the heat insulating section is small.
That is, the preheating unit 21 has a higher heating performance to the heating cylinder 12 than the heating unit 22, and the heat insulating unit 23 has a lower heating performance to the heating cylinder 12 than the heating unit 22.

As shown in Table 2, in the heating unit, the preheating unit, and the heat insulating unit, the inner case, the inner electric insulating material, the outer electric insulating material, the outer case, and the band can be shared, which facilitates the procurement of parts.

Further modifications of the heating element 25 will be described with reference to FIG.
As shown in FIG. 12 (a), the insulating plate 26 has a through hole 41. The through holes 41 are provided in a staggered pattern. The heating wire 27 is wound so as to pass through the through hole 41. The lower surface of the insulating plate 26 is the surface on the heating cylinder side.
As shown in FIG. 12 (b), the portion indicated by the length L1 faces the heating cylinder. The remaining length L2 is much shorter than the length L1. L1 is approximately 70% and L2 is approximately 30%.

FIG. 12 (c) shows a comparative example and corresponds to the cross-sectional view of FIG. In this comparative example, the length L3 faces the heating cylinder. This length L3 is approximately equal to the remaining length L4. Both L3 and L4 are 50%.
Considering that L1 and L3 greatly contribute to the heating of the heating cylinder, it can be said that the heating element 25 shown in FIGS. 12 (a) and 12 (b) is preferable to the heating element 25 shown in FIG.

In FIG. 3, the division in the vicinity of the bolt 37 has been described. The preferred position for this split is determined by thermal considerations. Preferred positions will be described with reference to FIG.
It is known that when an object is heated by a convection phenomenon, heat escapes upward from the upper surface of the object, and almost no heat escapes from the lower surface of the object.
From another point of view, the heat transfer coefficient on the upper surface of the object is much larger than the heat transfer coefficient on the side surface of the object. The heat transfer coefficient of the lower surface of the object is much smaller than the heat transfer coefficient of the side surface of the object.

As shown in FIG. 13A, in the heat insulating unit 23, when the split position is directly above the heating cylinder 12, the heat radiation q7 upward is increased, and the temperature control performance is enhanced.
As shown in FIG. 13 (c), in the preheating section 21, when the split position is directly below the heating cylinder 12, the downward heat dissipation q9 becomes smaller and the heating performance is improved.

As shown in FIG. 13B, in the heating unit 22, the split position is set to the side of the heating cylinder 12. A certain degree of heating performance can be obtained while maintaining a certain degree of temperature control performance.

The present invention is not applied to an injection device having only one or two band heaters in the heating cylinder 12, but is applied to an injection device having three or four or more band heaters. In the case of four or more, the four or more band heaters may include a preheating unit 21, a heating unit 22, and a heat insulating unit 23.

The present invention is suitable for an injection device in which a heating cylinder is provided with a preheating unit, a heating unit, and a heat insulating unit.

10 ... injection device, 11 ... nozzle, 12 ... heating cylinder, 13 ... screw, 20 ... heating mechanism, 21 ... preheating part, 22 ... heating part, 23 ... heat retaining part, 25 ... heating element, 31 ... inner case, 32 ... Inner electrical insulating material, 34 ... outer electrical insulating material, 34B ... thickened outer electrical insulating material, 35 ... outer case, 35B ... outer case with increased thermal conductivity, 36, 36B insulating plate 26 with band, q1 ... heating unit Heat transfer amount to the heating cylinder, q4 ... Heat transfer amount to the heating cylinder in the preheating part, q6 ... Heat transfer amount to the heating cylinder in the heat retaining part.

10 ... injection device, 11 ... nozzle, 12 ... heating cylinder, 13 ... screw, 20 ... heating mechanism, 21 ... preheating part, 22 ... heating part, 23 ... heat retaining part, 25 ... heating element, 31 ... inner case, 32 ... Inner electrical insulating material, 34 ... outer electrical insulating material, 34B ... thickened outer electrical insulating material, 35 ... outer case, 35B ... outer case with increased thermal conductivity, 36, 36B ... band, q1 ... heating cylinder in heating section Amount of heat transferred to, q4 ... Amount of heat transferred to the heating cylinder in the preheating section, q6 ... Amount of heat transferred to the heating cylinder in the heat retaining section.

Claims (7)

In an injection device including a heating cylinder having a nozzle at the tip, a screw housed in the heating cylinder so as to be rotatable and axially movable, and a heating mechanism wound around the heating cylinder.
The heating mechanism is arranged at a preheating portion arranged at the base of the heating cylinder, a heating portion arranged closer to the tip of the heating cylinder than the preheating portion, and a heating portion closer to the tip of the heating cylinder than the heating portion. It has a heat insulating part and
The preheating portion is configured to have higher heating performance to the heating cylinder than the heating portion.
The heat insulating unit is an injection device characterized in that the heating performance of the heating cylinder is lower than that of the heating unit. The injection device according to claim 1.
The heating portion covers the inner case wound around the heating cylinder, the inner electric insulating material covering the outer peripheral surface of the inner case, the heating element covering the outer peripheral surface of the inner electric insulating material, and the outer peripheral surface of the heating element. It consists of an outer electrical insulating material, an outer case that covers the outer peripheral surface of the outer electrical insulating material, and a band that covers the outer peripheral surface of the outer case.
The preheating section has the same structure as the heating section except that the outer electrical insulating material is thicker than the heating section.
The heat insulating unit is an injection device characterized in that at least one of the outer case and the band is made of a material having a high thermal conductivity with respect to the heating unit, and the other parts have the same configuration as the heating unit. The injection device according to claim 2.
An injection device characterized in that the outer electrical insulating material of the preheating portion is thickened by stacking the outer electrical insulating material of the heating portion. The injection device according to claim 1.
The heating portion covers the inner case wound around the heating cylinder, the inner electric insulating material covering the outer peripheral surface of the inner case, the heating element covering the outer peripheral surface of the inner electric insulating material, and the outer peripheral surface of the heating element. It consists of an outer electrical insulating material, an outer case that covers the outer peripheral surface of the outer electrical insulating material, and a band that covers the outer peripheral surface of the outer case.
The preheating section employs a heating element having a larger output per unit area than the heating section, and has the same configuration as the heating section except for the heating section.
The heat insulating unit is an injection device characterized in that a heating element having a smaller output per unit area than the heating unit is used for the heat insulating unit, and the other parts have the same configuration as the heating unit. The injection device according to any one of claims 2 to 4.
The inner case, the inner electric insulating material, the heating element, the outer electric insulating material, the outer case and the band are each divided at at least one place, and the divided positions are set so that the heating cylinder can be seen from the outside. An injection device characterized by being aligned. The injection device according to claim 5.
An injection device characterized in that the split in the heat insulating portion is positioned directly above the heating cylinder. The injection device according to claim 5.
An injection device characterized in that the split in the preheating portion is positioned directly below the heating cylinder.

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