CN1226133C

CN1226133C - Extrusion blow-molding process and blow-molding forming die

Info

Publication number: CN1226133C
Application number: CN 200310111049
Authority: CN
Inventors: 黄虹; 陈元芳; 夏华; 李军; 刘春�; 黄强
Original assignee: Chongqing Institute of Technology
Current assignee: Chongqing Institute of Technology
Priority date: 2003-11-29
Filing date: 2003-11-29
Publication date: 2005-11-09
Anticipated expiration: 2023-11-29
Also published as: CN1546305A

Abstract

The present invention discloses an extrusion blow molding forming process suitable for the production of middle plastic members and small plastic members and a blow molding forming die thereof. An extrusion machine head is used for extruding molten raw material into a tubular material blank; after being cut off, the tubular blank is moved back to a blow molding die with a plurality of die cavities for blow molding; the tubular blank needs to cover the contour areas of all the die cavities on the typing surface of the die; after the operation of die closure, the blow molding, cooling and shaping, the die is opened for taking members. A die body of the used blow molding forming die forms n die cavities by (n+1) inserts; each die cavity is formed by inserting and splicing two inserts in the axial direction of the die cavities; the inserts are connected and fixed by pins; the splicing surfaces of the inserts are provided with exhaust grooves; blank clamping cutting edges and surplus material grooves are arranged on the peripheries of the die cavities. The existing equipment is fully used by the blow molding process of extruding the die cavities by a single tubular blank for enlarging production scale and enhancing efficiency with low cost.

Description

The extrusion and blow molding method

Technical field

The present invention relates to a kind of plastics extrusion blow molding forming method, especially a kind of plastic single tube base is extruded the method for many types of chamber blow molding.

Background technology

The plastics extrusion blow molding moulding has become the third-largest forming method after plastic extruding forming, the injection moulding.Extrusion and blow molding is usually used in the processing and forming of containers such as bottle, bucket, kettle, jar, and is extensive at industry applications such as food, commodity, industrial chemicals and medicine.The technical process of extrusion and blow molding is: at first extrude a tubulose material base by extruder, pipe is moved in the blow mold of unlatching, close die feeds compressed air again, carry out inflation, cooling and shaping, die sinking pickup, making the pipe blow molding is a hollow plastic.

In traditional hollow plastic is produced, usually adopt the single tube base to extrude---the blowing of monotype chamber, once produce the mode of production of a plastic, or extrude n pipe, blow molding n plastic again, the quantity of extruding the quantity of pipe and blow molding plastic is 1: 1 relation.With this extrusion and blow molding method, the pipe of extruding is less, and less than cavity dimension, the blow molding die of use has a die cavity, generally at die cavity top and bottom design folder base cutting edge and clout groove is arranged, and utilizes the die joint of mould to carry out exhaust.The manufacture method and the manufacturing equipment of disclosed a kind of plastic hollow make-up machine of Chinese patent ZL91211808.3 and the disclosed a kind of hollow molding goods of Chinese patent ZL97196845.4 are applicable to that exactly this single tube base extrudes---the manufacture method and the equipment of the blowing of monotype chamber.

For large and medium-sized plastic, this method makes full use of resources such as equipment, the energy and manpower substantially.For middle-size and small-size plastic, generally its output require high, and the mode of production of one of a this mould often production efficiency is lower.And the power of extruder is bigger usually, and the plastic blow molding cycle is longer, fails to give full play to the efficient of extruder, causes the device resource waste.On the basis of existing equipment and human resources, for enhancing productivity, can consider to increase the discharging opening of cross-head, increase the quantity of extruding pipe, increase how secondary blow mold again and cooperate.But cross-head designs a plurality of discharging openings, complex structure not only, and cost height, and technology controlling and process difficulty are unsuitable for the production of middle-size and small-size plastic.Particularly for medium-sized and small enterprises, adopt this method cost that expands the scale of production too high.

Summary of the invention

The purpose of this invention is to provide a kind of extrusion and blow molding method that is suitable for producing middle-size and small-size hollow plastic, this method cost is low, technology controlling and process is simple, can make full use of existing equipments resources and enhance productivity.

For achieving the above object, the present invention adopts following scheme:

A kind of extrusion and blow molding method, plastic raw materials is added extruder behind fusion plastification, extrude a tubulose material base, again pipe is moved in the blow mold of unlatching, the mould closure, clamp material base, feed compressed air then, the inflation blank, die sinking pickup behind the cooling and shaping, it is characterized in that: the pipe bore that extruder is extruded is bigger, covers the contour area of all die cavities on die joint of blow mold, and employed mould has a plurality of die cavities;

For making plastic part quality higher, employed mold cavity pipe is relatively vertically arranged, that is: the pipe length of extruding can cover the length of a die cavity of mould, and the width of pipe can cover the profile of a plurality of die cavities.

Because the single tube base extrudes-production method of many types of chamber blowing still adopts cross-head to extrude single pipe, it is bigger only to need to change or manufacture and design the pipe bore that extrusion die extrudes it, re-use mould with a plurality of die cavities, device resources such as existing extruder have been made full use of, and the extrusion die of extruding the single tube base is simple in structure, manufacture and design easily, technology controlling and process is convenient, and the technological transformation cost is much lower than alternate manner.Use the blow molding mould in many types of chamber, but make a plurality of plastics of pipe one-shot forming, efficient improves greatly.Make in this way and can on original production equipment basis, expand the scale of production, raise labour productivity significantly and economic benefit.

For improving the quality of plastic, the relative pipe of mold cavity is vertically arranged, and the length of pipe can be not oversize, and the length of material base is suitable during with the blow molding of monotype chamber, can guarantee the plastic wall thickness unanimity of each mold cavity forming.

Because this production method requires a pipe will cover a plurality of die cavities, therefore be more suitable for the production of middle-size and small-size plastic.

Description of drawings

Below in conjunction with accompanying drawing the present invention is described in further detail.

Fig. 1 is an extrusion and blow molding method schematic diagram of the present invention;

Fig. 2 is a blow molding mould die body structural representation shown in Figure 1;

Fig. 3 is a die body B-B generalized section shown in Figure 2;

Fig. 4 is the C-C generalized section of middle mold insert 2 shown in Figure 2.

Among the figure: 1-die body mold insert, 2-die body mold insert, 3-die body mold insert, 4-air discharge duct, the clout groove between the adjacent die cavity of 5-, 6-clout groove, 7-folder base cutting edge, 8-compression section, 9-cross-head, 10-pipe, 11-blow molding mould, 12-die cavity

The specific embodiment

It is that low density polyethylene (LDPE), volume are the extrusion and blow molding method of the drug container plastic of 10ml that Fig. 1 shows a kind of manufactured materials.After plastic raw materials added the extruder fusion plastification, extrude a tubulose material base 10, move in the blow mold 11 of unlatching after will pipe 10 cutting off by cross-head 9.Mould 11 has two die cavities 12, and pipe 10 is vertically arranged relatively, and the length of pipe 10 is more longer slightly than die cavity 12, and its width can cover the overall width of two die cavities.Send into compressed air after the mould closure, the inflation stock, through cooling and shaping, the die sinking pickup.

Make and to utilize two plastics of a pipe blow molding in this way.Clearly, if mould is formed three die cavities by four mold inserts, can three plastics of a blow molding, by that analogy.Expand the scale of production, raise the efficiency with this method, only need to change the head 9 and the mould 11 of extruder, design is easy, and technological operation is convenient, and cost is low, and can make full use of current production devices.

Mold cavity 12 relative pipes 10 are vertically arranged, and have avoided its transversely arranged pipe wall upper-thin-lower-thick that causes, the situation that a molded item wall unevenness is even.

Fig. 2 illustrates this single tube base of enforcement and extrudes---the die body structure of the method blow molding mould of multi-cavity type blowing.Die body is formed 2 die cavities 12 by 3 mold inserts 1,2,3, and die cavity 12 is vertically arranged.Die cavity 12 becomes at the two lobe mold inserts combination edge spell shape perpendicular to the die joint direction by by mold cavity axis.Fix with pin connection or alternate manner between the edge body 1,2,3.The folder base cutting edge 7 of die cavity 12 peripheries is welded together blank, and plastic is separated with clout, makes plastic parts moulding.The intensity of welded side seam can be strengthened in folder base cutting edge 7 outer compression sections 8, and blank is welded together better.The 8 peripheries hopper 6 of having a surplus in compression section can hold more clout.

Fig. 3 shows the vent groove configuration on the mold insert 3 amalgamation faces.Upper, middle and lower at die cavity 12 has air discharge duct 4 respectively.Since adopt edge to piece together structure, on the amalgamation face of mold insert 1,2,3, can be easily with milling or other known technology processing air discharge duct 4.

The cross section structure of mold insert 2 in the middle of Fig. 4 shows.Because use a plurality of plastics of single tube blank molding, the clout that die cavity is 12 is more, use the clout groove 5 of the cross section of depression as circle, increased capacity, can reduce the width of clout groove, dwindle two distances between die cavity, reduced waste material.The cross section of use depression certainly, also can reach same effect for the clout groove of oval, trapezoidal or other shapes.

Claims

1. extrusion and blow molding method, after plastic raw materials added the extruder fusion plastification, extrude a tubulose material base (10) by cross-head (9), cut off after arriving certain-length, again pipe (10) is moved in the blow mold (11) of unlatching, mould (11) closure, clamp material base, feed compressed air then, the inflation stock, die sinking pickup behind the cooling and shaping is characterized in that: the material base that extruder is extruded (10) bore is bigger, cover the contour area of all die cavities (12) on die joint of blow mold (11), employed blow molding mould (11) has a plurality of die cavities (12).

2. a kind of extrusion and blow molding method as claimed in claim 1, it is characterized in that: the mould that uses (11) die cavity (12) relatively pipe (10) vertically arrange, the length of extruding pipe (10) can cover the length of (11) die cavities of mould, and the width of pipe (10) can cover the profile of a plurality of die cavities (12) on die joint.