FR2563146A1 - IMPROVED MOLDING APPARATUS - Google Patents

Abstract

IN THIS APPARATUS CONTAINING A CORE WITH WHICH IT DELIMITS A CAVITY FOR MOLDING AN ARTICLE WHOSE SHAPE PREVENTS THE EXTRACTION OF THE CORE IN A STRAIGHT LINE IN THE LONGITUDINAL DIRECTION, THE CORE EXPANDABLE IN THE MOLDING POSITION AND CONTRACTABLE IN THE RELEASE POSITION INCLUDES THE INDIVIDUAL RELEASE POSITION SEPARATED 17, 19, A SUPPORT ORGAN 9 TO CARRY THE SEGMENTS AND MEANS 25 TO MAINTAIN THE SEGMENTS AGAINST LONGITUDINAL DISPLACEMENT IN THE MOLD, THE SAID MEANS ARE CONSTITUTED BY RADIAL PROJECTIONS 25 OF THE SEGMENTS COOPERATING WITH CAVITIES OF THE ORGANE OF SUPPORT. THE SEGMENTS 17, 19 INCLUDE INCLINED SURFACES 43, 49 FORMING COUNTER CAMS THAT COOPERATE WITH THE SURFACES OF THE ACTUATOR 35, 37 SUCH SO THAT EACH SEGMENT CAN TILT AROUND ITS INDIVIDUAL AXIS 25 BETWEEN ITS DISTRIBUTED POSITIONS MOLDING AND RELEASE RESERREES, THE ACTUATOR 35, 37 COOPERATING WITH THE SAID SURFACES FORMING COUNTER-CAMS TO TILT THE SEGMENTS FROM ONE POSITION TO THE OTHER.

Description

The present invention relates to cores which can be expanded and

  mechanically tightened, used for molding plastic articles having internal surfaces which include threads, grooves in the cavities, perforations and other undercut shapes which are formed wholly or in part by means

  a core which has longitudinal segments available

  placed around a spindle extending longitudinally. Some-

  some adjacent segments are in contact inside the mold cavity and delimit molding surfaces

  contiguous for a corresponding surface of the wall

  dull molded part. To separate the core from the molded part, these contacting segments are moved radially inwards. We know a type of nucleus in which

  adjacent segments in contact are tightened radially-

  lie inward to allow removal, as described in U.S.A 3,660,001 but these cores have

  limitations due to the fact that they require a flexion of the seg-

  ment. Other cores in which adjacent segments are constricted radially inward, as described in U.S.-A 3,339. 242 or 3,482,815 or 3,584,111 or 4,131,264 also have limitations both in terms of prices and operation because they

  require complex sliding structures to guide

  der and / or carry out the radial displacement of the segments

tigus from the nucleus inward.

  An object of the invention is to provide a core which can be tightened radially inwards, in which contiguous segments are articulated to effect a rocking movement without the imposed condition of bending, with the inherent limitations, and in which the mounting and actuation of the segments is

  simple, economical and reliable.

  Another object of the invention is to provide a core which can be tightened inwards, in which adjacent segments are mounted so as to effect a rocking movement between their different positions by means of one (or more) actuating pin and in which the actuating pin retains the segments in

  their molding positions and, in preparation for moving

  ment adjacent segments to their other positions, it first removes this restraint and then initiates

  the rocking movement to the other position.

  The object of the invention is finally to provide a core which can be tightened inwards, of the aforementioned type, in which the actuating pin has separate cam surfaces in order to constrain each of the segments to

  toggle in its two directions respectively, these over-

  faces being spaced from each other so that after a displacement of the actuator

  in the opposite direction of its previous movement it pro-

  a delay in the tilting of the mold segments

  ge in reverse. This ensures freedom of movement

  segments and the actuating pin.

  Other features and advantages of the

  vention will appear during the description which follows

  vre made with reference to the accompanying drawing given solely by way of example and in which: Fig.l is a sectional view along the line

  1-1 of Fig. 2, of a tool to which the invention is applied

  tion; Fig. 2 is a partial top view at more

  large scale of the segments of the core assembled in the po-

  molding position; Fig.3 is a diagram showing the core segments of Fig.l in their release position; Fig.4 is an enlarged view of part A of the tool in FIg.l; Fig.5 is a sectional view of another embodiment of the invention;

  Fig. 6 is a diagram of the segments of the nucleus re-

  shown in Fig.5 in an intermediate position;

2 5 6 3 1 4 6

  Fig. 7 is a diagram showing the segments of the

nucleus in release position.

  The same references have been used in the drawings.

  these to designate analogous organs.

  Fig. 1 shows an embodiment of the invention for molding a plastic article which has a part of complex shape similar to a flange and having an internally threaded neck which in this example is offset, and which constitutes an opening to

  through the collar. The mold is represented in its po-

  closing location. It comprises a lower part 1 and an upper part 3 which are vertically separable along a dividing line 5. The lower part of the mold comprises a lower plate 7 on which rests a core assembly consisting of segments mounted in a support sleeve 9 which , in this example, includes split half-rings which are held together in

  a cylindrical bore of a lower retaining plate 11

  which is fixed by means of screws on an upper plate 13. The plate 13 delimits part of a mold cavity 15. In this example, twelve segments of

  nucleus of which six, alternating, 17, are analogous. On their parents

  external ripheries these segments are narrower than on the external peripheries of the interposed alternating segments 19 which in this example are also all analogous. The

  segments are assembled around a longitudinal axis com-

  mun 21 around a ring 21a in oversized grooves-

  born 21b in the segments. Each segment comprises

  te a pivoting projection 23 of semi-cylindrical shape the center of which is located at point 25, and each of them can pivot in a semi-cylindrical surface 29 formed in the sleeve 9. In their molding position shown in FIG. 1, the surfaces of the segments are in contact with a cylindrical bore 29 of the sleeve 9 and with a corresponding cylindrical bore 29 ′ in the plate 13, both centered on the axis 21. Inside the mold cavity,

  each segment is in contact with the adjacent segments.

  Threaded portions 31 of the respective segments are con-

  continuous from one segment to the adjacent segment and form a surface of a core for molding a continuous helical thread which in this example extends over at least 360 on the interior surface of the molded part. This is only an example in which the separation of the core from the molded product by a longitudinal displacement of one by

  relation to the other is made possible by a contrac-

  table. In each segment, when it is in

  the molding position of Fig.l, the surface 33 is in-

  inclined away from the adjacent surface 33 'of the

  sage of the sleeve 9 in order to allow the segment to tilt

  from its molding position in Fig. 1 to its position

  release release shown in Fig. 3. In the sleeve 9, the surface 33 'is inclined radially outwards

  from a curved surface 27 to the in-

sleeve 9.

  Each segment is switched between its two posi-

  tions by means of an actuator adapted for ef-

  back and forth between the position of

  molding shown in Fig.l and a release position

  tion shown in Fig. 2. The actuator includes

  takes upper and lower actuating pins 35 or 37 which are aligned on the axis 21. The pin 35 is fixed to a retaining member 39 which is held in the upper part 3-of the mold. In this example, the

  retainer forms part of the molding cavity 15.

  The spindle 35 has a conical upper actuating cam surface 41 which bears against corresponding cam follower surfaces 43 of the respective segments in order to tilt them and retain them in their molding position in FIG. When moving to this position, due to the downward closing movement of the part

  upper part of the mold, the lower part of the spindle

  35 pushes the cylindrical lower part of the

  lower spindle in a stop position in a bore

  a column 59 'and compresses a spring 45.

  After the completion of each molding operation

  ge, the upper part 3 of the mold rises with respect to the lower part 1, raising the spindle 35. This

  removes the force exerted by the surface 41 against the seg-

  elements, and releases the lower pin 37 which can thus follow the pin 35 upwards, under the action of the spring

  45. The pin 37 has an action cam surface 47

  nement, which cooperates with parts 49 of the segments 17 spaced from each other and which form counter-cams, forcing each of these segments to tilt around

  its own articulation axis 25. The upper extremities

  res of these six segments move inward, toward

  axis 21, this being permitted by the continuation of the movement-

  ment of the surface 41 of the spindle 35. If for any reason the rising cam ramp 47 tends to tilt any of the segments more quickly than is permitted by the spindle 35 which withdraws, this

  segment will hold pin 37 momentarily to prevent it

  song continue to rise, pin 35 continues its

  upward movement simply separated from spindle 37.

  Continuing its upward movement causes the cam ramp 41 to rise, thus allowing the tilting movement of this segment to be resumed by resuming the movement of the spindle 35 upwards. The actuating pins and segments suitable for tilting never interlock with each other during normal operation.

  In the position shown in Fig. 1, the par-

  lower links of the six segments 19 are spaced from the cam ramp 47, as indicated in 51. The commencement of the release movement by tilting of these segments is therefore delayed until the cam ramp 47 is sufficiently high to close space 51. At this

  moment the lower parts of the segments 17 have

  I moved inward to provide the necessary space

  to start the movement of the upper parts

  of the segments 19 inwards. The continued movement of pin 37 upwards causes the continued movement of the upper parts of the

  segments 17 and 19 radially inward. The movement

  ment of the spindle 37 is stopped by a rod 55 which is suspended from the spindle 37 and has a head 57 whose stroke is limited in a hole provided in the lower part of the column 59 'on which the sleeve rests

carrier 9.

  In this tool the movement of the parts of the mold

  the length of the segments 17 inwards exceeds twice the

  displacement of the corresponding ends of the segments 19.

  Part 3 of the mold continues its movement of

  separation of part 1 sufficient to allow

  put at least a usual ejection mechanism

ter the molded article.

  The mold can be closed in the usual way to repeat the molding process. This involves

  the lowering of part 3 of the mold towards the position re-

  shown in Fig. 1. The tail 59 of the spindle 35 has a diameter less than that of the opening delimited by the upper ends of the segments in their release position. In this descent, the tail 59 reaches the upper part of the spindle 37. At this time there exists

  a small space 53 (Fig. 3) between the conical surface 41 for-

  mant cam and the surfaces 43 of the segments. A continuation

  of the lowering of the spindle 35 causes a corresponding lowering

  of the spindle 37. This first removes the retaining pressure, if such pressure exists, exerted by the surface 47 against the lower ends of the

  segments 17, thus releasing them to allow their movement

  tipping to their molding position. During the continuation of the descent of the spindle 35 the surfaces 41 and 43 come into contact with, and cause all the segments to tilt, in their molding position shown in FIG. Pin 37 is pushed down, preventing

  thus any interference of this spindle with the

  ment of the lower parts of the segments towards the axis 21.

  The differences in the rocking motion of the different

  segments are obtained by differences in seg-

  ment. No particular circular alignment of the pins

  , 37 is only necessary with regard to a segment which

particular conch.

  Figs. 5, 6 and 7 show a variant of the in-

  vention in its application to a single spindle core, in this example for molding a plastic closure cap, with a neck having an internal thread. F g.5 is a sectional view which corresponds to that taken along line 1-1 of Fig. 2. In this example, as in the tool represented in FIG. 1, six identical alternating segments 2 and six identical alternating segments 4 are provided, interposed between the segments 2 and

  which correspond to segments 17 and 19 respectively,

  pictured in Fig. 2. Each segment 2 and 4 has a projection 23 the center of which is located at point 16 and

  can pivot in the surface 27, box in the tool shown

  felt in Fig.l; and the retaining ring 21a is provided in grooves 22b, as shown in FIG. 6, but not in FIG. 5 in order to better show the intervals

  34 and 36. Upper parts 6 and 8 form an over-

  continuous circular face for the core, comprising grooves

  ges which are continuous between adjacent segments so

  to constitute a helical thread 9 '.

  Segments 2-4 are assembled in a support

  consisting of a support sleeve 10 which has a bore

  cylindrical sage 12 which is connected with a bore 14 of

  conical shape inclined outwards, the center of the pivot

  ment 16 for each of the twelve segments being located at point

  which constitutes the junction of the two inclined parts coni-

  ques. An actuating pin 18 whose longitudinal axis coincides with the longitudinal axis of the sleeve 10 extends in the assembly of the segments. The spindle is circular in sections taken at right angles to the axis 20. In the molding position shown in Fig.5, the upper part of the spindle 18 forms a continuous surface with the upper parts of the segments . A view of

  above the assembled segments is shown in Fig. 2.

  In the molding position (Fig. 5) the conical surface 22 of the actuator is in contact with

  the corresponding surfaces 26-26 of the segments. The sail-

  lees 23 hold the segments against displacement

longitudinal in the sleeve 10.

  In the molding position, one end of the core assembly extends into a molding cavity 28 of a plate 30 delimiting the cavity which can move relative to the sleeve 10 and which meets it along a dividing line 32 The cavity is shaped in a manner corresponding to the external shape of the hat, the core ensuring the internal shape of the hat. The cap in its simplest form is a circular disc having a periphery or neck which surrounds it, the internal surface of which presents the thread-forming parts of the cap.

  on the threaded neck of a bottle or the like.

  After the molding operation, the pin 18 is

  retracted into its position shown in Fig. 7. When-

  as it moves in the intermediate position of Fig. 6, it ceases its retaining action on the end

  upper of segments 2-4, freeing them for their per-

  put an inward displacement in their position

  of release. Until the actuator has

  the position shown in Fig. 6 does not cause

  no such displacement due to the spaces 34 between the or-

  actuator gane and each of the six segments 2 and larger spaces 36 between the actuator and

the six segments 4.

  In the position shown in Fig. 6, the over-

  conical face 24 of the actuating member is in contact with the surfaces of the six segments 2 which face it, and

  the widest part of the actuator is so-

  killed well below (axially) the center of articulation 16. The continuation of the descent of the actuating member

  ment switches each of the 2 elements around the articu-

  lation 16 towards their release position but has no immediate action on the segments 4 due to the greater width of the space 36. When the descending actuator has closed the space 36 the continuation of its descent forces it to also tip these segments. At this time the heads of six of the segments 2 have moved sufficiently towards the axis 20 to provide space for the corresponding movement of the heads 8. Thus, as in the

  embodiment of Fig. 1, space 36 is sufficient

  larger than space 34 so that segment 4 lowers

  rolls over about half the tilting stroke of the

  segment 2. In the position of Fig.6, the upper part

  re 38 of spindle 18 has sufficient clearance relative to the sides of segments 2-4 to avoid interference with the commencement of tilting of the segments to the

position of Fig. 7.

  To toggle the segments from the posi-

  release of Fig. 7 by bringing them back into the po-

  molding section in Fig. 5 to repeat the mold cycle

  lage, the actuating member 18 is moved upwards.

  Its initial displacement releasing the holding pressure on

  the lower ends of all segments leaving them

  being free to move inward, but this

  cement is not caused by the actuator until

  that the periphery of the upper part 38 of

  the actuating member reaches the surfaces 26 of the segments

  2. This constitutes a position notably above the axis of articulation 16 in the direction of movement.

  axial of the actuator. It is at this point

  faces 26 of segments 2 that the initial forces are applied

  quées to cause their tilting in their molding positions. At this moment the lower conical surface 24 of the actuating pin 18 is sufficiently close to the final position of FIG. 5 so that the surface 24 of the pin 18 does not hinder a radial movement towards the interior of the lower parts of the segments, caused by the opposite movement of the upper parts of the

  segments by the rise of the actuating member 18. When-

  that the segments 2 tilt towards their positions of movement

  lage, they switch the interspersed segments 4 towards

  their molding positions. When segments 2 have

  dyes their molding positions, the segments 4 have also

  reached their molding positions, as shown

in Fig. 2.

  In the movement of the actuating member from the molding position shown in Fig.5 to the position shown in Fig.6, this member creates a

  space between the upper part 38 of the action member-

  and the segments (Fig. 6) before the tipping movement of the segments is initiated. There is thus sufficient space between the segments and the upper part

  38 recessed so that the rocking motion

  ment of the lower ends of the segments, which is pro-

  voiced by the descent of the actuator is not prevented by parts of the segments above the points

  hinge 16 striking the upper part in re-

pin line 18.

Claims (7)

  1- Molding apparatus delimiting with a core   a cavity for molding an article of which at least one part   tie is hollow and in which the shape of the article excludes   an extraction of the core from the right molded article li-   in the longitudinal direction, the core being expandable   in a molding position and contractable in a posi-   release, characterized in that it comprises separate individual segments (2, 4, 17, 19), a support member (9, 10) of the segments comprising means (25, 26)   to maintain these against any longitudi-   nal in the mold and constituting pivot axes (16, 25) for the respective segments, so that   each segment can tilt around its individual axis   duel between a separated molding position and a contracted release position, and an actuating member   (18, 35, 37) to toggle the segments of one of the say positions in the other.   2- Apparatus according to claim 1, character-   risé in that the support member (9, 10) surrounds the segments (2, 4, 17, 19), said segments being disposed between the actuating member (18, 35, 37) and the   support, each segment comprising a first and a second   against surfaces forming counter-cams (43, 49) facing the actuating member, and spaced from one another in the longitudinal direction of the segments and the axis (16, 25)   each segment being located between the two   your two surfaces (43, 49) of each segment forming a counter   cams, means being provided for moving the actuating member   in order to tilt the segments in their   release positions while the molded article is in the   always in the mold cavity, and the means of re-   holding (16, 25) of each segment keeping it against any longitudinal displacement under the action of the force exerted to cause it to tilt from its molding position 12 - in its liberation position.   3- Apparatus according to claim l, characterized in that the individual pivot axis (16, 25) of each segment (2, 4, 17, 19) is located between the ends of the segment, so that when the one end of it moves radially in one direction, its other end moves radially in the opposite direction.   4- Apparatus according to claim 1, character-   se in that the positions of the segments (2, 4, 17, 19) during   that they are in the molding position in the mold cavity extend together over 360, each segment being in contact with the adjacent segments inside said cavity.   5- Apparatus according to claim 1, character-   laughed in that the segments (2, 4, 17, 19) are arranged around the longitudinal axis of the actuating member (18, 35, 37) and are adapted to be able to tilt around their respective axes (16 , 25) by getting closer and   moving away from the longitudinal axis (20, 21) of the actuating member   at least some of the relevant segments (18, 35, 37)   adjacent to each other, said segments forming together in their molding position in which they are contiguous and in contact with each other   the others in the cavity, continuous surfaces of the ar- molding.   6- Apparatus according to claim 1, character-   laughed in that the means for retaining the segments are constituted by said support member (9, 10) and in that said segments comprise associated means (13, 25) by which the respective segments are articulated in   said support member (9, 10) for carrying out their movements-   respective tipping elements, said associated means   joint limiting the longitudinal movement of each   that segment with respect to the support member which carries the segments.   7- Apparatus according to claim 1, character-   laughed in that said retaining means comprise for each segment a projection (16, 25) directed radially outwards, the support member (9, 10) comprising cavities in which extend said projections   (16, 25) and in which these revolve, the di-   your cavities limiting the longitudinal displacement of the seg-   respective elements with respect to the support member.