GB1584818A

GB1584818A - Apparatus for moulding plastics material products

Info

Publication number: GB1584818A
Application number: GB36942/77A
Authority: GB
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1977-09-05
Filing date: 1977-09-05
Publication date: 1981-02-18

Description

(54) APPARATUS FOR MOULDING PLASTICS MATERIAL PRODUCTS (71) We, AMP INCORPORATED, a corporation organised and existing under the laws of the State of New Jersey, United States of America, of Eisenhower Boulevard, Harrisburg, Pennsylvania, U.S.A., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to apparatus for moulding plastics material products.

Injection moulding apparatus is known which includes a rotatable wheel having a plurality of circumferentially spaced mould cavities formed on its periphery, and a nozzle assembly arranged adjacent the wheel periphery for injecting plastics material into each mould cavity in turn during rotation of the wheel.

With known apparatus the wheel is rotated in step-wise manner thereby t6 position each mould cavity in turn in alignment with the injection nozzle for filling with plastics material whereby the apparatus will produce individual moulded products which are stripped from the mould cavities at a position remote from the injection nozzle.

It is also known to use such apparatus to form moulded products -on a separate carrier strip which is fed about the periphery of the wheel and between the injection nozzle and the periphery of the wheel.

With such products - the carrier strip is normally to remain an essential part of the complete product produced.

However, in the field of, for example, electrical connector housings, there is a need for a strip-form arrangement of moulded products, (that is housings) comprising a plurality of moulded products carried by a carrier strip which will be removed from the products prior to use thereof.

The provision of products in such a strip form arrangement can enable the products to be used with automatic assembly apparatus in which, for example, in the case of electrical connector housings, an electrical terminal is inserted into each housing, whereafter the housing is removed from the carrier strip.

According to the invention there is provided apparatus for moulding plastics material products, comprising a wheel having a plurality of circumferentially spaced mould cavities formed on its periphery; means to continuously rotate the wheel about its axis; a nozzle assembly having an outlet arranged to inject plastics material into a space between the nozzle outlet and the periphery of the wheel as the periphery of the wheel rotates past the nozzle outlet; control means to control the spacing between the nozzle outlet and the periphery of the wheel such that products formed in the mould cavities are. interconnected by an integrally formed strip of the plastics material formed on the periphery of the wheel; and at least one core pin individually asso ciated with each mould cavity and carried by the wheel, the core pin being movable relative to the mould cavity during rotation of the wheel to permit withdrawal of a moulded product from the mould cavity.

An embodiment of the invention and modifications of the embodiment will now be described, by way of example, with reference to the drawings in which: Figure 1 is a schematic side view, partly in cross-section of injection moulding appatus according to the invention..

Figure 2 is a perspective view of a wheel and a nozzle assembly forming part of the apparatus of Figure 1 Figure 3 is a perspective view, partly in cross-section, of a portion of the wheel of Figure 2, showing two core pin assemblies; Figure 4 is an exploded perspective view of the two core pin assemblies of Figure 3 Figure 5 is a timing diagram; Figure 6 is a schematic perspective view of a hopper forming part of the apparatus of Figure 1 ; Figure 7 is a schematic side view of a modified wheel for use with the apparatus of Figure ; figure 8 is a section on the line 8 - 8 of Figure 7; Figure 9 is a schematic side view of a further modified wheel for use with the apparatus of Figure 1; Figure 10 is a cross-sectional perspective view through a mould cavity in the wheel of Figure 9; Figure 11 is a perspective view of a modified nozzle assembly for use with the apparatus of Figure 1; Figure 12 is a cross-sectional view through the wheel, core pin assembly and nozzle assembly of Figure 2; Figure 13 is a perspective view of an arrangement for controlling the spacing be tween the periphery of the wheel and the outlet of the nozzle assembly shown in Figure 2; and Figure 14 is a plan view of a strip of electrical connector housings formed with the apparatus of Figure 1.

Referring first to Figures 1, 2 and 12, the injection moulding apparatus 1 comprises a rotatable wheel 2 having a plurality of circumferentially spaced mould cavities 3 foamed on its periphery. A nozzle assembly 4 forming part of an injection unit 5 is positioned adjacent the wheel periphery for injecting plastics material 6 such as nylon, polypropylene, polysulfone, polypheneleneoxide or the like to be moulded, into each cavity 3 in turn during continuous rotation of the wheel 2.

In Figure 1 pellets of thermoplastic plastics material 6 are supplied from a hopper 7 to a screw feed mechanism 8 by way of a tube 9. Heating elements 10 are positioned around the screw feed mechanism 8 to maintain the plastics material in a molten condition as it is moved from right to left, as shown in Figure 1, by the mechanism 8.

The molten plastics material is forced by the screw feed mechanism 8 into the nozzle assembly 4, and thus into the cavities 3 as they pass successively by the nozzle assembly 4 during continuous rotation of the wheel 2 by means of a motor 18 about a shaft 19 in a clockwise sense.

As will be described later with reference to Figure 13, the spacing between the outlet of the nozzle assembly 4 and the periphery of the wheel 2 is controlled such that a strip 13 of the plastics material 6 is formed on the periphery of the wheel 2, which strip is integrally formed with, and thus interconnects in strip form, the products formed in the mould cavities 3. The spacing between the outlet of the nozzle assembly 4 and the periphery of the wheel 2, the speed of rotation of the wheel 2, and the rate of supply of molten plastics material 6 to the nozzle assembly 4, are all controlled to ensure complete filling of the mould cavities 3 and formation of the strip 13 on the periphery of the wheel 2, preferably without any of the plastics material flowing beyond the edges of the periphery of the wheel 2.

After the molten plastics material has been injected into the mould cavities 3 and onto the periphery of the wheel 2, the material is cooled -and thus hardened, by means of a water spray 12.

Referring to Figure 14 also, the resulting strip of moulded products (in this case electrical connector housings 100) is then taken from the periphery of the wheel 2, and by means of a belt and roller arrangement 11 is fed to a cutting station 14 which functions to cut lateral edge portions 101 from the strip 13 to give the strip straight, clean edges, and then to a stamping station 15 which functions to stamp out portions 102 of the strip 13 from between adjacent moulded housings 100.

The strip of moulded housings 100 is then rolled on a reel 16 for transfer to automatic assembly apparatus (not - shown) which operates to insert an electrical terminal 103 (Figure 14) into each housing 100, for subsequent crimping of the thus formed connector to a wire 104.

A hopper 80 is provided adjacent the wheel 2 for inserting an insert, if required, into each cavity 3 in turn on rotation of the wheel 2 and prior to the injection of the plastics material 6 into the cavities 3. The structure and operation of the hopper 80 will be explained in more detail later with reference to Figure 6.

Referring also to Figures 3 to- 5, two core pins 20, 21 are associated with each mould cavity 3 and carried by the wheel 2.

The core pin 20 forms part of an assembly 23 and is carried at one end of an elongate block 22 of generally rectangular crosssection. The end of the block 22 carrying the core pins 20 defines a shoulder 27. Two spaced holes 24 pass through the block 22.

A rib 26 depends from the block 22. The rib 26 fits into a channel 28 in a cylindrical rod 30. The rod 30 has threaded holes 32 for -receiving fasteners 34 which initially pass through the hole 24 to attach the block 22 to the rod 30. The rod 30 is received within a tubular portion 36 of a cam member 38 via an open end 40 of the tubular portion. Between the opposite closed end 42 of the tubular portion 36 and the adjacent end of the rod 30 are positioned a plurality of biasing means in the form of spring washers 44. The rod 30 is maintained within the tubular portion 36 by a pin 46. The rod 30 is biased resiliently against the-pin -46 by the washers 44. The rib 26 extends out of the tubular portion via a slot 48. The external configuration of the tubular portion 36 is semi-cylindrical.

A plate 50 extends from the closed end 42 of the tubular portion 36 and carries a roller follower 52. The core pin 21 forms part of an assembly 25 which is in substance the same as assembly 23, and the same reference num erals are.u$ed to indicate identical parts.

An assembly 23, - 25 is inserted into a cylindrical bore 54 on the periphery of the wheel 2 on each side if and in alignment with each mould avity 3. The roller fol- lowers 52 each extend into an individual cam track 58 formed in a sttionary disc--6Q.

The discs 60 are positioned one ion each side of the wheel 2. The insertion of the assemblies 23, 25 into their respective forms 54 must be done either in the absence of the stationary discs 60 or by suitable access means in the stationary discs. Such an access means is shown in.th.e form of a member 62 which can be removed by undoing a screw 63.

The tubular portions 36 slide in their respective bores 54 and will move there pins 20, 21 relative to the mould cavity 3, that is into and out of the mould cavity 3, during rotation of the wheel 2, according to the position of the followers 52 in the tracks 58 as .will be explained.

Referring in particular to Figure 5, there is indicated the movement of the core pins 20, 21 of one mould cavity 3 during a 360 rotation of the wheel 2. The two core pins 20, 21 are shown in their closed position at 0 , which point is also marked " INJECT ".

The word " INJECT " implies that a mould cavity 3 is immediately adjacent the outlet of the nozzle assembly.4. -More specifically, the centre line 131 of the mould cavity 3 is in line with nozzle assembly 4 and the plastics material is.flowing into the cavity 3.

The spacing between-the surface of the nozzle assembly 4 and the periphery of wheel 2 is only about 0005" to 0 010".

The core pins 20, 21 remain in their closed position during a dwell period between 0 and-approximately 105 . After the wheel 2 has rotated through 105 the tracks 58 begin to diverge and cause the roller followers 52 to transmit to the assemblies 23 and 25 a linear sliding movement causing them to separate and, more specifically, the core pins 20, 21 to withdraw from the.cavity 3. Maximum withdrawal occurs after the wheel 2 has rotated about 165 . The core pins 20, 21 are now in their maximum withdrawal position and will re -main so until the wheel 2 has rotated another 30 . Then, after 1950.of rotation the tracks 58 will begin to converge to cause the core pins 20, 21 to begin moving back into cavity 3. Such a movement of the core pins 20, 21 into the cavity 3 will continue until the wheel 2 has rotated 345 , at which time the core pins 20, 21 will be completely inserted into the -cavity 3 and will be ready for the next cycle of plastics material injection, which occurs at 3'60 (the equivalent of 0 ).

The moulded plastics product formed in the cavity 3 is -remoyed fr0in the wheel 2 before the wheel has rotated a fuli 360 .

As can be seen from Figure 5, such.removal of the plastics product olccu.rs'while the core pins 20, 21 are In their maximum with- drawal position between the angular positions 165 and 195' of wheel 2 - As shown in Figure 2 the nozzle assembly 4 includes a nozzle plate 70 having a concave surface facing the periphery of the wheel 2. An outlet groove 74 Is formed in the plate 70 and orifices 76 positioned in the groove 74.extend through the plate 70 to communicate with a passageway through which the plastics material.6 is fed.

The size, number and disposition of the orifices 76 in the nozzle plate 70 are a matter of choice depending amongst other factors on the shape of the mould cavities 3.

For example, the orifices could, as shown in Figure 2, be arranged in alignment in a groove 74 extending circumferentially of the wheel 2, with the diameter of the orifices 76 becoming larger from the top to the bottom orifice.

Referring now to Figure 6, the hopper 80 for inserting preformed inserts, such as metal ferrules 82, into the cavities 3, is pro vided adjacent the periphery of the wheel 2.

The hopper 80 includes a reservoir 84 which in use contains a large number of the ferrules 82 in loose piece form. A vibrator .86 is employed to vibrate the ferrules 82 into a vertical tube 88. The. bottom of the tube 88 terminates near .the periphery of the wheel 2 -so that as the cavities 3 pass in turn under the tube 88 one of the.ferrules 82 will drop into each cavity 3.

In a modifica.tion, the hopper 80 is equipped with a feed mechanism which is actuated by a lever and pawl arrangement.

.When the lever on the feed mechanism is engaged by a pawl on the periphery of the wheel 2, a ferrule is released from the-tube 88 on to the surface of the periphery so that it drops into a vasant mould cavity 3.

A modified wheel 2a is shown in Figures 7 and 8, in which a core pin 20a associated with a mould cavity 3a is carried by the wheel 2a but is movable relative to the mould cavity 3a in a radial.sense.

-The core pin 2a is mounted -on a shaft .90 which extends through the core pin.

One.each end of the shaft 90 is a roller follower 52a. Each roller - follower .52a extends into a.cam track 58a in a stationary disc.60a. The wheel 2a in-.effect encom passes the discs 60a. On rotation of the wheel 2a relative to the discs 60a the roller followers 52a move along their respective cam tracks 58a and transmit a radial movement to the core pin 20a so that it moves into and out of the mould cavity 3a.

In a modification, two or more core pins can be mounted on the shaft 90.

In yet another modified wheel 2b shown in Figures 9 and 10, a threaded core pin 20b is associated with each mould cavity 3b being mounted for rotational movement within the mould cavity 3b.

The mould cavity 3b is defined by movable dies 91, and the core pin 20b extends into the cavity 3b. A shaft 92 extends radially inwardly of the wheel 2b from each core pin 20b into the hollow interior of the wheel, and carries a gear 94. The gears 94 of the core pins 20b all engage a stationary rack 96.

In use, after a threaded plastics material nut 98 has been formed in a cavity 3b around threaded core pin 20b, the dies 91 will move to the left and to the right respectively, so that the nut 98 can be removed.

Actual removal of the nut 98 is effected by rotating the threaded core pin 20b via the shaft 92. Thus, as the wheel 2b moves inwardly into the plane of the pauper containing Figure 10 the gear 94 will move with the wheel and rotate on stationary rack 96 and will cause the threaded core pin 20h to unscrew itself from the nut 98, and thereby force the nut outwardly, that is upwardly in Figure 10, and away from the wheel 2b.

It is to be noted that molten plastics material 6 is forced not only into each cavity 3b but also forced into a narrow slot 200 between the dies 91 to create an enlarged carrier strip portion 201.

However, the carrier strip portion 201 is not essential since the nuts 98 will in any event be connected together by the strip of plastics material formed on the periphery of the wheel 2b, that is on the outer surfaces of the dies 91.

Referring now to Figure 11, a modified nozzle assembly 4c is shown having two spaced outlet grooves 496, 497 formed in the nozzle plate 70c, as well as a slot 78c.

Each groove 496, 497 has three orifices 76e and each communicates with a different source of plastics material. To maintain separation within the nozzle assembly between the plastics materials emanating from the different sources, a disc 492 is provided having a gating slot 500. The slot 500 is aligned with the groove 496 and allows plastics material from a source (not shown) arranged axially of the nozzle assembly 4c to enter only the groove 496. The groove 497 communicates with a source 493 of plastics material via a tube 501 and plastics material from source 493 enters only the groove 497.

The slot 78c in the nozzle plate 72c serves for the formation of an enlarged carrier strip portion similar to the portion 201 of Figure 9. The slot 78c is open at its end facing in the direction of rotation of the adjacent wheel (not shown in Figure 11).

As molten plastics material is forced out of the orifices 76c in the slots 496 and 497 to fill the mould cavities in the wheel and form the carrier strip on the periphery of the wheel, the material will also flow into the slot 78c to form the continuous enlarged carrier strip portion.

Referring now to Figure 13, there is shown control apparatus for controlling the spacing between the nozzle assembly 4 and the periphery of wheel 2.

Such spacing is critical to the satisfactory formation of the carrier strip 13 about the periphery of the wheel 2.

The control apparatus includes a stationary plate 461 and a positioning plate 468 which is mounted on four guide rods 464 which are rotatable about their axes relative to the plates 461 and 468.

The shaft 19 on which the wheel 2 rotates is supported on plates 462 and 463 which also support the non-rotating discs 60 (not shown) which contain the cam tracks 58. The plates 462 and 463 are secured to a carrier plate 467 which is movable in a direction normally to its major surfaces along the rods 464, and is thereby able to move the wheel 2 towards and away from the nozzle assembly 4.

A pair of identical pivoted lever arrangements 480 and 475 are coupled from their centre pivot points 473 and 481 to the bifurcated end of a shaft 469 by linkages 474 and 476.

The shaft 469 is movable, in the direction of its longitudinal axis, by suitable means, such as a hydraulically operated piston (not shown), thereby to reduce or increase the effective length of the pivoted lever arrangements 480 and 475, and thereby move the plate 467, and with it the wheel 2, towards or away from the nozzle assembly 4 to provide for coarse positioning of the wheel 2 relative to the nozzle asembly 4.

Fine positioning of the wheel 2 relative to the nozzle assembly 4 is effected by means of a chain drive 483 which is engaged about four cogs 482 secured to the ends of the four rods 464 respectively on the outside of the plate 468. The rods 464 have threaded portions received in nuts 465 which are secured to the inside surface of the plate 468. Movement of the chain 483 (by means not shown) causes rotation of the cogs 482 and thus of the rods 464 on which the cogs 482 are secured. This rotation of the rods 464 causes the plate 468 to move along the rods 464 due- to the engagement between the rods 464 and the nuts 465 on the plate 468. Movement of the plate 468 causes movement of the plate 467 along the rods 464 since the lever arrangements 475 and 480 are in a rigid condition when there is no movement of the linkages 474 and 476 relative to the arrangements 475 and 480. Thus the position of the plate 467 and thus also the wheel 2, can be accurately set relative to the nozzle assembly 4 as required.

WHAT WE CLAIM IS: 1. Apparatus for moulding plastics material products, comprising a wheel having a plurality of circumferentially spaced mould cavities formed on its periphery; -means to continuously rotate the wheel about its axis; a nozzle assembly having an outlet arranged to inject plastics material into a space between the nozzle outlet and the periphery of the wheel as the periphery of the wheel rotates past the nozzle outlet; control means to control the spacing between the nozzle outlet and the periphery of the wheel such that the products formed in the mould cavities are interconnected by an integrally formed strip of the plastics material formed on the periphery of the wheel; and at least one core pin individually associated with each mould cavity and carried by the wheel, the core pin being movable relative to the mould cavity during rotation of the wheel to permit withdrawal of a moulded product from the mould cavity.

2. Apparatus as claimed in Claim 1, in which each core pin forms part of an asembly slidably received in a bore formed in the periphery of the wheel and positioned on one side of and in alignment with the associated mould cavity, the assembly including a roller follower extending into a cam track formed in a stationary disc positioned adjacent one side of the wheel so that on rotation of the wheel the roller fol lower moves along the cam track and transmits a linear sliding movement to the assembly thereby moving the core pin into and out of the associated mould cavity.

3. Apparatus as claimed in Claim 2, in which the assembly includes a block carry ing the core pin, the block being attached to a cylindrical rod which is received in a tubular portion of a cam member, the rod being maintained in the tubular portion by a pin, spring washers for biasing the rod against the pin, the roller follower being carried by a plate extending from the tubular portion, the tubular portion being a slide fit in the bore.

4. Apparatus as claimed in Claim 1, in which the core pin is mounted for movement radially relative to the associated mould cavity.

5. Apparatus as claimed in Claim 4, in which the core pin is mounted on a shaft having a roller follower which extends into a cam track formed in a stationary disc encompassed by the wheel so that on rotation of the wheel the roller follower moves along the cam track and transmits a radial movement to the core pin.

6. Apparatus as claimed in Claim 1, in which the core pin is mounted for rotational movement within the mould cavity.

7. Apparatus as claimed in Claim 6, in which the core pin is threaded and is arranged to be rotated on rotation of a gear mounted for movement with the wheel, which gear engages a stationary rack.

8. Apparatus as claimed in any one of Claims 1 to 7, including a hopper positioned adjacent the wheel for inserting an insert into each mould cavity in turn prior to injection of plastics materiol into the mould cavity.

9. Apparatus as claimed in any one of Claims 1 to 8, in which the nozzle assembly includes a nozzle plate having a concave surface adjacent to the periphery of the wheel, the surface having an outlet groove in which is formed at least one orifice communicating with a source of plastics material.

10. Apparatus as claimed in Claim 9, in which two spaced outlet grooves are formed in the surface of the nozzle plate, each groove having at least one orifice, and each groove communicating with a different source of plastics material.

11. Apparatus as claimed in Claim 9 or Claim 10, in which a slot is formed in the surface of the nozzle plate on a line lying in a plane normal to the rotational axis of the wheel, the slot being open at its end facing in the direction of rotation of the wheel past the nozzle plate, the slot being filled with plastics material during filling of the mould cavities, to form an enlarged thickness portion on the strip formed on the periphery of the wheel.

12. Apparatus as claimed in any one of Claims 1 to 11, in which the control means comprises a carrier plate on which the wheel is mounted, the plate being movable along guide rods towards and away from the nozzle assembly, and positioning means to effect movement of the plate along the guide rods.

13. Apparatus as claimed in Claim 12, in which the positioning means comprises two pivoted lever arrangements coupling the carrier plate to a positioning plate mounted on the guide rods, and means to vary the effective length of the pivoted lever arrange ments thereby to alter the distance between the carrier plate and the positioning plate

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. along the rods 464 due- to the engagement between the rods 464 and the nuts 465 on the plate 468. Movement of the plate 468 causes movement of the plate 467 along the rods 464 since the lever arrangements 475 and 480 are in a rigid condition when there is no movement of the linkages 474 and 476 relative to the arrangements 475 and 480. Thus the position of the plate 467 and thus also the wheel 2, can be accurately set relative to the nozzle assembly 4 as required. WHAT WE CLAIM IS:

1. Apparatus for moulding plastics material products, comprising a wheel having a plurality of circumferentially spaced mould cavities formed on its periphery; -means to continuously rotate the wheel about its axis; a nozzle assembly having an outlet arranged to inject plastics material into a space between the nozzle outlet and the periphery of the wheel as the periphery of the wheel rotates past the nozzle outlet; control means to control the spacing between the nozzle outlet and the periphery of the wheel such that the products formed in the mould cavities are interconnected by an integrally formed strip of the plastics material formed on the periphery of the wheel; and at least one core pin individually associated with each mould cavity and carried by the wheel, the core pin being movable relative to the mould cavity during rotation of the wheel to permit withdrawal of a moulded product from the mould cavity.

and thus between the wheel carried by the carrier plate and the nozzle assembly.

14. Apparatus as claimed in Claim 13, in which the positioning plate is mounted on the guide rods by engagement between threaded portions of the guide rods and nuts carried by the positioning plate, and including means to rotate the guide rods thereby to move the positioning plate along the guide rod, such movement of the positioning plate causing corresponding movement of the carrier plate, and thus of the wheel carried by the carrier plate, relative to the nozzle assembly, the pivoted lever arrangements serving as rigid connections between the carrier plate and the positioning plate during such movement.

15. Apparatus as claimed in any one of Claims 1 to 14, in which each mould cavity is defined by one or more die members movable relative to the remainder of the wheel to permit removal of a moulded product from a cavity.

16. Apparatus for moulding plastics material products, substantially as hereinbefore described with reference to Figures 1, 2, 3, 4, 5, 12 and 13 of the drawings.

17. Apparatus for moulding plastics material products, substantially as hereinbefore described with reference to Figures 1, 2, 3, 4, 5, 6, 12 and 13 of the drawings.

18. Apparatus for moulding plastics material products, substantially as hereinbefore described with reference to Figures 1, 2, 3, 4 5, 7, 8, 12 and 13 of the drawings.

19. Apparatus for moulding plastics material products, substantially as hereinbefore described with reference to Figures 1, 2, 3, 4, 5, 9, 10, 12 and 13 of the drawings.

20. Apparatus for moulding plastics material products, substantially as hereinbefore described with reference to Figures 1, 2, 3, 4, 5, 11, 12 and 13 of the drawings.

21. A strip of moulded products manu- factured with apparatus as claimed in any one of Claims 1 to 20.