JPH04275124A - Heat generating device in hot runner apparatus in synthetic resin injection molding machine - Google Patents

Abstract

PURPOSE:To increase a heating surface per a predetermined range and to enhance heating efficiency by a method wherein a spiral ridge is cut in the leading end heating body integrated with a main body member and a spiral hole is cut in the main body part on the leading end side of the internal receiving space at the leading end part of the leading end heating body in the spiral hole. CONSTITUTION:The receiving space 12a facing to the interior of a gate not shown in the drawing is formed to the leading end part 12 of a main body part 11 having a receiving space 12a formed therein so as to be allowed to face to the interior of the hot runner of an injection molding machine and a fixing spiral hole 12b is formed on the leading end side of the receiving space 12a. A main heating body 21 relatively large in the generation quantity of heat for heating the synthetic resin in the runner to always hold the same to a molten state is spirally built and arranged in the receiving space 11a of the main body part 11 along the inner peripheral surface of said space 11a. Further, a leading end heating body 31 again melting the synthetic resin material temporarily cooled and solidified at a gate part to close a flow path is inserted in the receiving space 12a of the leading end part 12 through the center part of the main heating body 21 to be screwed in and fixed to the spiral hole 12b.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a heating element device in a hot runner system of a synthetic resin injection molding machine.
More specifically, it is designed to accommodate the installation conditions given to the injection molding section of a synthetic resin injection molding machine, to enable good installation, and to effectively obtain the expected amount of heat. This invention relates to an improvement of a heating element device in a hot runner system.

0002

[Prior Art] A heating element device in a hot runner system of a synthetic resin injection molding machine is a heating element device in which a tip heating element is installed in a runner leading to the injection molding section of the synthetic resin injection molding machine, that is, the gate part of the cavity. The synthetic resin material inside is heated and held in a molten state, and the tip part of the tip heating element is made to face the gate part so that the gate part can be locally heated,
At the time of non-injection molding, the synthetic resin material that temporarily closes the gate part by being cooled and solidified is instantly melted by local heating of the gate part by this heating element every time an injection molding operation is performed. , which opens the gate and injects the molten synthetic resin material into the cavity to form the desired resin molded product, and is widely used in runnerless injection molding machines for high-precision resin molding. There is.

[0003]The heating element device in this type of hot runner system is generally formed into a bullet-shaped external shape, and as described above, the heating element device is formed in a corresponding portion of the main body member facing into the runner. The runner has a built-in main heating element with a relatively large amount of heat that heats the synthetic resin material in the runner and keeps it in a molten state at all times. The corresponding part of the tip member, which is formed to have a small diameter corresponding to the opening surface, has a synthetic resin material that is relatively cooled and solidified at the gate part at the time of non-injection molding. of,
It has a built-in tip heating element that intermittently heats and melts each injection molding operation.

Therefore, in the heating element device constructed as described above, it is particularly necessary to form the outer diameter of the tip portion of the tip heating element facing the gate portion to be extremely small. For example, the set inner diameter of the gate part is φ1.0mm to 2.0mm.
On the other hand, the allowable outer diameter of this tip portion is only approximately φ0.2 mm to 0.6 mm at the tip surface, and the outer diameter of the tip heating element built into the tip portion is significantly limited. That will happen.

For this reason, in the conventional case, a rod-shaped tip heating element using a heat generating material such as a nichrome wire heater is welded and fixed to the tip of the device, or a nichrome wire heater with an even smaller diameter is used. Measures are taken such as folding it in half and putting it inside.

[0006]

[Problems to be Solved by the Invention] However, in the case of the heating element device in the conventional hot runner system having the above configuration, the rod-shaped tip heating element is not necessarily completely fixed by welding using a small-diameter nichrome wire heater. Moreover, in this case, there is a disadvantage that finishing work is required for the welded part, and on the other hand, since the heating element is a simple rod-shaped tip, the amount of heat generated is insufficient. , which required a relatively large current to flow in order to generate the necessary amount of heat.

[0007] The present invention has been made to solve these conventional problems, and its purpose is to reduce the required amount of heat, especially with respect to the tip heating element built in the tip portion of the device. An object of the present invention is to provide a heating element device for a hot runner system of a synthetic resin injection molding machine of this type, which can be easily obtained with a relatively simple structure.

[0008]

[Means for Solving the Problems] In order to achieve the above object, a heating element device in a hot runner system of a synthetic resin injection molding machine according to the present invention includes a rod-shaped tip heating element using a relatively small diameter nichrome wire heater. A spiral strip is carved in a required range of the heating element at the tip corresponding to the tip of the device, and the tip is fixed by screwing into a spiral hole formed in the tip of the device. It is.

That is, the present invention provides a heating element device in which a main heating element is built in an internal housing space of a main body member, and a tip heating element is built in an internal housing space of a distal end portion integrated with the main body member. A spiral strip is formed on the tip heating element, and a spiral hole is formed on the tip side of the internal accommodation space at the tip of the main body member, and the tip of the spiral strip of the tip heating element is formed into a spiral strip at the tip of the main body member. This is a heating element device in a hot runner system of a synthetic resin injection molding machine, characterized in that it is screwed and fixed into a hole.

0010

[Function] Therefore, in the heating element device of the hot runner system of the synthetic resin injection molding machine according to the present invention, since the spiral thread extending over a predetermined range is carved at the tip of the tip heating element, the spiral thread is The effective surface area of the forming part is made relatively large compared to a simple rod shape,
The heat generating surface per predetermined range in the single unit increases, and the relative heat generation amount, in other words, the electric power required to obtain the required heat generation amount can be reduced. Fixing the tip heating element by screwing with a spiral strip makes it extremely easy to assemble the entire device configuration, improves heat conduction of the tip heating element to the tip of the main body, and does not require any finishing work afterward.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heating element device in a hot runner system of a synthetic resin injection molding machine according to the present invention will be described in detail below with reference to FIGS. 1 to 9.

FIG. 1 is a cutaway side view showing the general structure of a heating element device in a hot runner system of a synthetic resin injection molding machine to which this embodiment is applied.
FIG. 2 is an enlarged cross-sectional view of the distal end portion of the device.

That is, in the configuration of the embodiment shown in FIG.
12 shows a main body member of the device that has a housing space 11a formed therein, and 12 also faces a gate portion (not shown), and has a housing space 12a inside and a spiral hole 12b for fixing at the tip side of the housing space 12a. These main body members 11 and the distal end portions 12 are integrally formed into a substantially bullet-shaped outer shape, as is clear from the illustrated embodiment. There is.

Further, reference numeral 21 has a relatively large amount of heat generated, which is arranged spirally along the inner peripheral surface of the accommodation space 11a of the main body member 11, and which heats and maintains the synthetic resin material in the runner in a molten state at all times. A main heating element 31 is inserted into the accommodation space 12a at the tip end portion 12 of the main body member 11 through the center of the main heating element 21 disposed in the accommodation space 11a, and extends over a required range. A spiral strip 31a is carved, and its tip is fixed by screwing into the spiral hole 12b, or if necessary, using a heat-resistant conductive adhesive, and then the injection molding operation is performed. The synthetic resin material, which is intermittently energized and temporarily cooled and solidified at the gate to close the flow path, is heated and melted again to open the flow path.The tip generates the required amount of heat. It is the body.

Therefore, in the case of the embodiment device having the above configuration, since the spiral strip 31a is carved over a predetermined range at the tip of the tip heating element 31, the effectiveness of the spiral strip 31a is reduced in the area where the spiral strip 31a is formed. The surface area is relatively increased compared to a case formed into a simple rod shape.

That is, for example, when comparing the actual measurements when the spiral strip 31a is engraved on the rod-shaped tip of the tip heating element 31 and when the rod-shaped tip is left as is, it is found that the length of the rod-shaped portion is 5 mm. , when the outer diameter is set to 0.8 mm, it becomes as follows. In the former case, a spiral strip 31a is carved on the rod-shaped tip. Screw module = 1, screw pitch = 0.25,
If the thread angle = 60°, the effective surface area is approximately 5
It becomes 2.4mm2. If the latter is left in the shape of a rod. Its effective surface area is approximately 12.6 mm2. Therefore, the effective surface area of the former is approximately 4.16 times that of the latter.

In this way, the tip heating element 3 in the embodiment
The effective surface area of 1 is substantially increased, which together with the phenomenon of the applied current flowing along the surface and the preferential heat dissipation phenomenon due to the sharpened thread tip,
The heat generating surface and resistance value per predetermined range in a single unit increase, and a high-density heat generating element is constructed, for example, similar to tightly wound nichrome wire heaters, and as a result, the relative heat generation amount also increases. As a result, the amount of power required to obtain the required amount of heat can be reduced.

FIGS. 3 to 9 show temperature characteristics A of the tip heating element according to the conventional example, temperature characteristics B of the tip heating element according to the embodiment, and temperature characteristics C of the micron tip heating element according to separate specifications. Power on for 6 seconds at the specified temperature, 14
A comparison of temperature characteristics when electricity is stopped for sec is shown.

Here, FIG. 3 shows the temperature difference when each tip heating element is used singly in an atmosphere at room temperature, and FIG. 4 shows the temperature difference when each tip heating element is used individually in an atmosphere at room temperature. Figure 5 shows the temperature difference when the temperature of the heating element is set to 200°C. Figure 5 shows the temperature difference when the temperature of the main heating element is set to 250°C with the tip heating element installed in the device at room temperature. Figure 6 Figure 7 shows the temperature difference when the tip heating element built into the device is set in an atmosphere at room temperature and the temperature of the main heating element is set at 300℃. Figure 8 shows the temperature difference when the temperature of the main heating element is set to 200℃.
Figure 9 shows the temperature difference when the temperature of the main heating element is set to 250°C in an atmosphere of 300°C.
The temperature difference when the temperature of the main heating element is set to 300°C in an atmosphere of 300°C is shown.

[0020] It is clear from these comparison tables that the effects of this example device are remarkable.

[0021] On the other hand, the spiral hole 12b of the tip member 12
Fixing the helical thread 31a on the tip heating element 31 by screwing makes it extremely easy to assemble the entire device configuration, and has the advantage that no finishing work is required after fixing.

[0022]

Effects of the Invention As described in detail above, according to the heating element device in the hot runner system of a synthetic resin injection molding machine according to the present invention, the main heating element is provided in the internal housing space of the main body member, and is integrated with the main body member. In a heating element device in which a tip heating element is built in an internal accommodation space of a tip part of a main body member, a spiral strip is engraved on the tip heating element, and the tip side of the internal accommodation space at the tip part of the main body member is provided with a spiral strip. Since a spiral hole is carved and the spiral strip at the tip of the tip heating element is screwed and fixed to the spiral hole at the tip of the main body member, the tip is carved over a predetermined range at the tip of the tip heating element. The effective surface area for heat generation in the spiral strip is relatively large compared to the conventional simple rod-shaped heating element configuration, and the heat generating surface area per predetermined range in a single unit increases, and the relative In other words, it is possible to reduce the power consumption to obtain the required calorific value, and it is also possible to reduce the power consumption to obtain the required calorific value. This makes it extremely easy to assemble the entire device configuration, improves the heat conduction of the tip heating element to the tip of the main body, and does not require any finishing work after assembly.Furthermore, the structure itself is extremely simple. It has excellent features such as being easy and inexpensive to implement.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view showing a schematic configuration of a heating element device in a hot runner system of a synthetic resin injection molding machine to which an embodiment of the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of the distal end portion of the device.

[Figure 3] Temperature difference between the tip heating element according to the conventional example, the tip heating element according to the embodiment, and the micro-sized tip heating element according to separate specifications when each tip heating element is used alone in an atmosphere at room temperature. This is a graph showing.

FIG. 4 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere at room temperature and the temperature of the main heating element is set to 200°C.

FIG. 5 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere at room temperature and the temperature of the main heating element is set to 250°C.

FIG. 6 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere at room temperature and the temperature of the main heating element is set to 300°C.

FIG. 7 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere of 200°C and the temperature of the main heating element is set at 200°C.

FIG. 8 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere of 250°C and the temperature of the main heating element is set at 250°C.

FIG. 9 is a graph showing the temperature difference when the tip heating element incorporated in the above device is in an atmosphere of 300°C and the temperature of the main heating element is set at 300°C.

[Explanation of symbols]

11 Main body members of the device 11a Accommodation space 12 Tip part of main body member 12a　Accommodation space inside the tip part 12b Spiral hole 21 Main heating element 31 Tip heating element 31a Spiral strip at the tip of the tip heating element

Claims (1)

[Claims] 1. A heating element device in which a main heating element is built in an internal accommodation space of a main body member, and a tip heating element is built in an internal accommodation space of a distal end portion integrated with the main body member, wherein the tip heating element A spiral hole is formed on the tip side of the internal accommodation space at the tip of the main body member, and the tip of the tip heating element is screwed and fixed to the spiral hole. A heating element device in the hot runner system of a synthetic resin injection molding machine.