JPH0515536B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electric heating element for a heating channel tool having a heating conductor, the heating conductor being located within and away from the heating channel. It is of the type arranged in the injection passage which branches and leads to a series of outlets of the heating passage tool.

BACKGROUND OF THE INVENTION In a heating channel tool with an electric heating element known from Australian Patent No. 286607, the heating conductor is constructed in the form of a rod or wire. The heating conductor is arranged centrally in the heating channel of the heating channel tool and forms a loop in the region of the injection channel branching off from the heating channel.
The legs of this loop extend adjacent to the inner surface of the injection passage. In such known heating channel tools, this rod-shaped or wire-shaped heating conductor is deformed under the sudden load exerted by the plastic melt flowing into the heating channel, so that the heating channel tool is heated. There is a risk of contact with the surface. This contact results in a short circuit and interruption of operation.

In addition, the known heating conductor has the same cross section at every location, so that the heat generation is the same at every location.

Since the heating conductor is designed in the form of a loop in the area of the injection channel, which can only be used for injection channels with a relatively large diameter, the known heating channel tool is designed to ensure that the injection ports in the mold cavity are located at a small distance from each other. It cannot be used in injection molds that produce injection molded parts with small dimensions.

Problem to be Solved by the Invention It is an object of the invention to improve an electric heating element of the type mentioned at the outset so as to provide a heating channel tool with heating elements in which the inlets of adjacent mold cavities are spaced at a small distance from each other. The object of the present invention is to enable the provision of a mold corresponding to an injection mold having a mold cavity row such as that arranged in the above.

Means for Solving the Problem According to the invention, the heating conductor is an electrical resistance heating element and is constructed as a flat member, and the heating conductor is an electrical resistance heating member and is constructed as a flat member, and the heating conductor is configured as a flat member on the side of the flat member that is directed toward the outlet. tongues are provided, each of the tongues extending to the extent of one outlet;
and the distance between each of these two adjacent tongues is in the range of 5 mm to 15 mm, and the end of the flat member has an electrical resistance lower than that of the flat member for applying a voltage to the flat member. This problem is solved by the fixed connection plate.

According to one advantageous embodiment of the invention, the free end of the tongue of the flat element is designed as a point.

Due to the fact that the heating conductor is formed from a flat member and a series of tongues, it has sufficient mechanical strength and dimensional stability, so that it can absorb the melted material flowing into the heating channel. It can satisfactorily absorb sudden loads caused by objects.

To fix the heating conductor in position, support pins made of insulating material are provided. This support pin rests on the side surface of the flat element and is designed, for example, as a screw. This support pin is mounted in a threaded hole in the heating passage tool and can be actuated from the outside.

Embodiment The heating channel tool 1 consists of an upper part 2 and a lower part 3. This upper part 2 is releasably connected to the lower part 3 by a screw 4. A bush 5 is provided in this upper part 2, which bush 5 forms an inlet for the plastic melt. The flow passage formed by this bushing 5 opens into a heating passage 6. Inlet channels 7 extend from this heating channel 6 and each extend to an outlet 8 .

The heating channel tool 1 is provided with a heating conductor 9 which has a flat member 10 . This flat member 10 is manufactured from a material with a high specific electrical resistance. This flat member 10
has a tongue piece 11 protruding toward the side facing the outlet 8;
is provided. The tongues 11 each extend in the area of the outlet 8. The free end of this tongue is designed as a point. This tongue piece 11
may be configured integrally with the flat member 10,
Alternatively, it may be manufactured as a separate component and fixed to the flat member 10. If constructed separately, the material of the tongue can be different from that of the flat element. The tongue has a higher specific electrical resistance than the flat member because it is desired to increase heat generation within the tongue.

For this purpose, a notch 1 is also made above each tongue.
2 or 13 may be provided, by providing this cutout the current density in the area of the tongue is increased. As shown in FIG. 1, the three-dimensional shape of this notch can vary.

In order to concentrate the heat generation in the heating conductor mainly in the area of the flat member 10 and the tongue piece 11, the connecting plate 1 is provided at the end of the flat member 10 in the illustrated embodiment.
4 is welded at weld point 15 for applying voltage. The specific electrical resistance is significantly lower in this connecting plate 14 than in the flat element 10.

As can be seen in FIG. 4, a support screw 16 made of an insulating material, for example a ceramic material, is provided for fixing the flat element 10 in position. This support screw 16 is screwed into a threaded hole in the heating channel tool and is accessible from the outside.

As is clear from FIG. 1, the spacing between two adjacent tongues is very small, so that this heating channel tool can be adapted to injection molds in which the inlets of the mold cavity are slightly spaced from each other. It can be placed as follows. The spacing between two adjacent tongues is in the range of 5 mm to 15 mm.

[Brief explanation of drawings]

Figure 1 is a partially sectional view of the heating passage tool;
Figure 2 is a sectional view taken along the - line in Figure 1;
This figure is a view of the heating passage tool shown in FIG. 1 viewed from the direction of the arrow, and FIG. 4 is an enlarged view of a sectional view taken along the line - in FIG. 3. 1... Heating passage tool, 2... Upper part, 3... Lower part,
4... Screw, 5... Bush, 6... Heating passage, 7... Injection passage, 8... Outlet, 9... Heating conductor, 10... Flat member, 11... Tongue piece, 12, 13... Notch, 14... Connection plate, 15...Welding location, 16...Supporting screw.

Claims (1)

[Scope of Claims] 1. An electric heating member for a heating passage tool having a heating conductor, the heating conductor extending within the heating passage and branching from the heating passage into a series of heating passage tools. In the version in which the heating conductor 9 is arranged in the injection channel leading to the outlet, the heating conductor 9 is an electrical resistance heating element and is designed as a flat element 10, of which the heating conductor 9 is directed towards the outlet 8. Laterally projecting tongues 11 are provided, each of which extends in the area of one outlet 8, and the distance between each two adjacent tongues 11 is between 5 mm and 15 mm. is within the range of
and a connecting plate 14 having a lower electrical resistance than the flat member 10 for applying a voltage to the flat member 10 is fixed to the end of the flat member 10. for,
Electric heating element with heating conductor. 2. The heating member according to claim 1, wherein the free end of the tongue piece 11 is configured as a pointed end. 3. The heating member according to claim 1 or 2, wherein the tongue piece 11 is integrally formed with the flat member 10. 4. The heating member according to claim 1 or 2, wherein the tongue piece 11 constitutes a separate component. 5. The heating member according to claim 4, wherein the material of the tongue piece 11 is different from the material of the flat member 10. 6. The heating member according to claim 5, wherein the tongue piece 11 has a higher specific electrical resistance than the flat member 10. 7. The heating member according to any one of claims 1 to 6, wherein a support pin made of an insulating material is in contact with a side surface of the flat member 10. 8. Heating element according to claim 1, wherein the support pin is configured as a screw 16 screwed into a screw hole of a heating channel tool. 9. The heating member according to any one of claims 1 to 8, wherein cutouts 12 and 13 are provided above each tongue piece 11 in the flat member 10.