JPS6235818A - Injection molding equipment for forming sandwich - Google Patents

Abstract

PURPOSE:To enable to uniformize the flow speed of resin to be skin layer in future by a structure wherein the cross-sectional area of a secondary supplying passage, one end of which communicates with a primary resin passage and the other end of which communicates with a connecting passage to connect a secondary injection unit with an injection head, is made smaller than that of the primary resin passage. CONSTITUTION:Grooves 9 and 9 meet at the starting end of a contracted diametral part 5C and communicate with a primary resin passage A. In addition, the basic end of the part 5C freely communicates with a through-hole 10 formed on the periph eral wall of an inner tube 5B. The through-hole 10 freely cmmunicates with a connecting passage which connects a secondary injection unit 2B with an injection head 1. A secondary supplying passage D consists of the through-hole 10 and the grooves 9 and 9. The total cross-sectional area of resin passage at the arbitrary loca tion in the divergent portion X of the grooves 9 and 9 is set smaller than the cross-sec tional area of the primary resin passage A. At the boundary portion between the primary resin passage A and the grooves 9 and 9, the depth (h) of the grooves 9 and 9 gradually decreases towards the tip part to increase the flow speed of resin and thus uniformize the flow speed by decreasing the flow speed at the primary resin passage A.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding device for sandwich molding, which is equipped with a pair of injection devices 1.

(Prior Art) An injection molding device used to mold a sandwich molded product, in other words, a plastic multilayer molded product, generally includes a pair of injection devices consisting of a heating tube and a scrim, and a common injection device. The injection head includes a first resin passage for guiding molten resin from one injection device to the mold cavity, and a second resin passage for guiding molten resin from the other injection device to the mold cavity. A resin passage is formed.

During injection molding, is it necessary to use resin as the skin layer of the molded product? ! After being injected into the mold cavity through the c1 resin passage, the resin that will become the core is transferred to the second resin passage. It is injected into the mold cavity through the injector.

(Problems to be Solved by the Invention) In the conventional example as described above, the first resin passage next to the resin passage to form the skin layer is usually formed in an annular shape, but the flow rate of the resin is lower than the passage. Specifically, as will be described later, the flow velocity of the resin is high at two locations that are axially symmetrical with respect to the axis of the first resin passage, and therefore the flow rate of the resin is non-uniform in the circumferential direction within the mold cavity. Because as much resin as possible flows into the skin layer in the part that is to be renovated,
When resin is injected to form the core in such a state, the amount of resin that becomes the core will be reduced by the amount that has flowed into the skin layer, and as a result, the molded product will have a thick skin layer at two axially symmetrical locations, and vice versa. In other words, the core has a concave shape at the two locations of the Todoromon.

The present invention has been made to solve these problems, and its entire purpose is to provide an injection molding apparatus for sandwich molding that can make the flow rate of resin as a skin layer as uniform as possible.

(Means for Solving the Problems) The present invention provides communication between one end that communicates with the 111th oil passage formed by the reduced diameter portion of the outer nozzle and the inner nozzle, and the second injection device and the injection head. The cross-sectional area weight of the second supply passage having the other end communicating with the communication passage is smaller than that of the first resin passage.

(Function) The molten resin injected from the second injection device flows into the first resin passage through the communication passage and the second supply passage, flows through the first resin passage at a nearly uniform flow rate, and flows through the outer nozzle hole. After that, it is filled into the mold holes and bits.

(Example) Hereinafter, how to carry out the present invention will be explained with reference to all the drawings. In FIGS. 1 and 2, 1 is an injection head, and the injection head 1 includes a pair of first and second Is the second injection device 2A, 2B the communication path 3A, 3B? connected via.

These will be explained in full order below.

The injection head iFi, an outer nozzle 4, an inner nozzle 5 which is reciprocatably inserted into the Kl side nozzle 4 and has a reduced diameter tip and is provided with a gap from the inner peripheral surface of the outer nozzle 4; The actuating rod 6 is inserted into the inner nozzle 5 in a reciprocating manner and has a diameter-reduced tip and is spaced apart from the inner circumferential surface of the inner nozzle 5.

The outer nozzle 4 consists of a nozzle tip 4A and an outer tube 4B, and the base end of the nozzle tip 4A is fitted into the tip of the outer tube 4B.6 The inner nozzle 5 consists of a nozzle tip 5A and an inner tube. 5B, the base end of the inner cylinder 5B has an enlarged diameter, and the outer peripheral surface of the expanded diameter part is in close sliding contact with the inner peripheral surface of the outer cylinder 4B, and the inner cylinder 5BO has a reduced diameter part 5C and a nozzle tip. 5A
A gap is provided between the outer cylinder 4B and the first resin passage Ai. The operating rod has a reduced diameter at its distal end, and its proximal end is in close sliding contact with the inner circumferential surface of the inner cylinder 5B, and the reduced diameter part 6A of the operating rod 6, the nozzle tip 5A, and the inner cylinder 5B.
The gap therebetween constitutes a second resin passage Bi. and,
Nozzle holes 4C and 5D formed in the outer and inner nozzle tips 4A and 5A are arranged coaxially, and the tip of the actuating rod 6 is connected to the inner nozzle tip 5.
The nozzle hole 5D at A can be closed.

Further, on the surface of the proximal end of the rod 6, there is a pair of grooves 7 whose width gradually increases toward the distal end.
7 are formed at substantially axially symmetrical positions, the grooves 7.7 intersect with each other at the starting end position of the reduced diameter portion 6A, and communicate with the second resin passage B. FIGS. 3 to 5 show how the groove 7.7 widens toward the end.

The base end of the groove 7.7 is formed in the peripheral wall of the inner vJ5B and can freely communicate with the i through hole 8, and the through hole 8 is
As will be described later, it can freely communicate with a communication path between the first injection device 2A and the injection head 1. This through hole 8 and groove 7,
7 constitutes a first supply path Cr.

Such a groove is also formed on the circumferential surface of the inner cylinder 5B,
It is designated by the reference numeral 9 in FIGS. 1-5. Similarly to the above, the grooves 9, 9 also intersect with each other at the starting end position of the reduced diameter portion 5C to communicate with the first resin passage AK, and the base end thereof also connects to the inner cylinder 5B at a position approximately axially symmetrical to the through hole 8. It can freely communicate with a through hole 10 formed in the peripheral wall, and the through hole 1
0 can freely communicate with a communication path between the second injection device 2B and the injection head 1, as will be described later. This through hole 10
and groove 9.9 constitute a second supply path. Groove 9.9
The expanded state is also shown in FIGS. 5-5.

FIG. 6 shows all the essential parts of the present invention, and shows the cutting of the resin passage at any point within the end widening section X of the groove 9.9 formed in the inner cylinder 5B and constituting the finger passage. The area is the first
It is set smaller than the cross-sectional area of the resin passage A. More specifically, the cross-sectional area of the first resin passage A is preferably about 1.5 times the cross-sectional area at the midpoint M of the section X.

The reason why the cross-sectional area of the first resin passage A is made larger than that of the groove 9.9 is to slow down the flow velocity of the resin and make the flow velocity completely uniform in the circumferential direction of the passage A. In order to further enhance this effect, K is the tip of the inner cylinder 5B,
It is preferable to reduce the cross-sectional area near the proximal end of the nozzle tip 5A on the inner side, and to close the entire resin flow path. For this reason,
As shown in FIG. 2, an annular projection 11 is formed on the outer periphery of the inner cylinder 5B at this location. 7 to 9 show changes in the cross-sectional area of the first resin passage A.

FIG. 10 shows the resistance diagram of the second part of FIG. 6, that is, the boundary between the first resin passage A and the groove 9.9. The depth h of the groove 9.9 is tapered so as to decrease in two directions toward the tip.

The reason why the resin is tapered is to once narrow the resin flow path to increase the flow speed and then slow down the flow in the first resin passage A to make the flow speed uniform. In FIG. 6, reference numeral 12 indicates a branch area formed approximately at the center of the mold grooves 9, 9, which is embossed on the curved surface of the inner cylinder 5B. As described above, in the conventional example, the resin flowed quickly in this branch area 12.12.

Please note that the dotted line Y in FIGS. 2 and 6 indicates the conventional first resin passage.

Figure 11 shows the velocity distribution of resin in the first tree passage.
A comparison is made between the conventional example and the present invention. Figure (a) shows the conventional speed distribution, and Figure (b) shows the speed distribution 1 of the present invention. The horizontal axis represents the speed v, and the vertical axis represents the speed distribution 1. is the tip of the watershed 12
It represents the road distance d in the circumferential direction from .

By the way, returning to FIG. 6, reference numeral 13 denotes a pair of storage grooves extending along the longitudinal direction of the inner cylinder 5B, which are equidistant from a line segment l parallel to the axis passing through the tip o'fr of the dividing area 12. located at the location.

The storage groove 13.13 flows from the through hole 8.10 and does not flow into the groove 9.9, but is connected to the inner cylinder 5B and the cylinder 14 described below.
This is to prevent the two types of resins that have flowed into the gap between them from merging.

Returning to FIG. 1, as mentioned above, 2A and 2B are injection devices, and this injection device 2A.

2B is the heating cylinder 15A, 15B and the heating cylinder 15, respectively.
A, 15BK screw 15C inserted so that it can freely reciprocate,
As described above, the injection head 1 and the first . One end of the communication paths 3A, 3B that fully communicate with the second injection devices 2A, 2B is connected, and the other end of the communication paths 3A, 3B is connected to the base end of the outer cylinder 4]3' of the injection head 1. Through holes 14A and 14B of cylinder 14
Further, the through holes 14A and 14B are connected to the inner cylinder 5.
It passes through the peripheral wall of B and communicates with a through hole 8.10 also shown in FIG. Note that the base end portion of the inner cylinder 5B is also fitted into the cylinder 14.

Next, the operation of the device according to the above configuration will be described.
The first injection device 2AIC supplies the resin for the core, and the second injection device 2B supplies the resin for the skin layer and melts them, and first, they are retreated into the inner cylinder 5B' by a cylinder device (not shown). In this state, the communication path 3B and the through hole 10 are in communication with each other. Therefore, when the second injection device 2B' is injected, the molten resin for skin nozzle is completely connected to the groove 9.9 and the first resin path A. The liquid is then injected from the nozzle hole 4C into various molds as shown in the figure.

FIG. 13 shows the amount of resin flowing into the first resin passage A' by the distance Y from the axis, and the magnitude of the supply amount is indicated by suffixes 1 to n. As is clear from the figure, when the supply amount is the same, the distance r is the same at all locations.In other words, as shown in Figure 14, the distance r at two axially symmetrical locations is the same. Since r is larger than other parts, more resin will flow into the part corresponding to this part of the mold than the other parts, and therefore, the resin will flow into the part corresponding to that part of the mold. , the resin for A is not filled and the core 16 is not filled as shown in FIG.
Two recesses 17 are formed in the mater and skin layers 18.
Two convex portions 19 will be formed. In this regard, in the present invention, as shown in FIG. 16, it can be seen that the thickness of the skin layer 18 is uniform.

If the injection of the resin to form the skin layer is completed by applying the pressure as described above, then the inner nozzle 5 is advanced to come into contact with the outer nozzle 4, and the operating rod is retracted by a cylinder device (not shown). When the resin for the skin layer is injected from the second injection device 2B, the molten resin is transferred to the first supply path C.
The resin flows into the second resin passage B through the inner nozzle hole 5D.
Then, it is filled into a mold (not shown).

(Effects of the Invention) As is clear from the above, the cross-sectional area of the first resin passage is larger than that of the second supply passage, so the molten resin is decelerated in the first resin passage, and the flow rate is is uniform, so
The amount of resin for the skin layer filled into the metal cavity is
They are the same at all locations, and therefore the appearance of the core resin filled into the mold cavity is the same at all locations, resulting in a molded product having a skin layer of uniform thickness. Become.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the apparatus according to the present invention, FIG. 2 is a sectional view showing the injection head of FIG. 1, and FIGS. 6 is a side view showing essential parts of the present invention, FIGS. 7 to 9 are sectional views taken along lines 2-2, Hoch line, and Hohe line in FIG. 2, respectively, and FIG. 10 is a side view showing essential parts of the present invention. is an enlarged view of part 2 of Fig. 6, Fig. 11 (a) is a velocity distribution diagram of conventional resin, Fig. 1
Figure 1 (b) is a velocity distribution diagram of the present invention, Figure 12 is a cross-sectional view along the Taut line in Figure 2, Figure 15 is an explanatory diagram showing the state of resin flow in the present invention, and Figure 14 is a conventional diagram. FIG. 15 is a sectional view showing a conventional molded product, and FIG. 16 is a sectional view of a molded product according to the present invention. 1... Injection heads 2A, 2B... 1st. Second injection devices 3A, 3B...Communication path 4...Outer nozzle 5...Inner nozzle 6...Operating rod A...First resin passage B...Second resin passage C... 1st supply route D...2nd supply route Patent applicant Kinkinsha Awa-sama Seisakusho'

Claims (1)

[Scope of Claims] The first and second injection molding devices are provided with an injection head common to the injection molding apparatus, and the injection head includes an outer nozzle and an inner side that is reciprocatably fitted into the outer nozzle and has a reduced diameter tip. a first resin formed by a nozzle, an operating rod that is reciprocatably fitted into the inner nozzle and has a reduced diameter end portion, an outer circumferential surface of the reduced diameter portion of the inner nozzle, and an inner circumferential surface of the outer nozzle. a second resin passage formed by the outer circumferential surface of the reduced diameter portion of the operating rod and the inner circumferential surface of the inner nozzle, and one end of which is connected to a communication path connecting the first injection device and the injection head , and a first supply path whose other end communicates with the second resin passage; one end which communicates with a communication passage which communicates the second injection device and the injection head, and whose other end communicates with the first resin passage. an injection molding apparatus for sandwich molding, further characterized in that the cross-sectional area of the first resin passage is larger than that of the second supply passage.