FR2479082A1 - METHOD FOR INJECTION MOLDING OF PLASTIC BINS FOR ELECTRIC BATTERIES AND BATTERIES AND MOLD FOR CARRYING OUT SAID METHOD - Google Patents

Abstract

INJECTION MOLDING. MOLDING PROCESS BY INJECTION OF ACCUMULATOR BINS CHARACTERIZED IN THAT IT CONSISTS OF PROVIDING THE INJECTION INTO THE FOOTPRINT OF A MOLD 1 THROUGH HOLES 9-9 LOCATED AT THE LEVEL OF TWO OPPOSITE WALLS 11 OF THE BIN TO BE OBTAINED AND AT AN INTERMEDIATE HEIGHT BETWEEN THE BOTTOM 13 DUDIT BAC AND ITS UPPER EDGE.

Description

The present invention relates to a method of injection molding of

  hollow body of plastic material affecting the section of a quadrilateral and more

  particularly batteries for batteries, electric accumulators

  triques and the like. The invention also relates to a mold

  perfected for the implementation of the method.

  In the construction of electric batteries and accumulators, plastic bowl-shaped bodies having a bottom, peripheral walls and an upper opening are used, these bodies being intended to contain the

  components of each module of the electrical appliance.

  These bins are currently being prepared according to a technique

  known and widely followed by a molding process

  on injection molding machines which provides for the injection of

  plastic in the mold, carried out at one end

  mite of the tray to obtain, and more precisely on the bottom or the upper edge. The injection of plastic material can be performed at one or more points of the bottom or the edge of the tray, but in all cases, it always takes place parallel to

  the axis of the body, or along the length of the lateral walls

the bac.

  Such a molding technique requires that the walls of the tray to be obtained are thick to allow filling of the plastic mold and to obtain final dimensions respecting the required tolerances. In practice, you can not

  make containers with thin walls.

  Currently, although the trend would be to

  thin-walled tanks, no results were obtained.

satisfactory conditions.

  The possibility of reducing the thickness of the walls of the bins having the indicated destination would above all have the advantage of a noticeable saving in plastic material, in addition to a reduction in weight. However, the injection process

  discussed above and so far does not allow it.

  The plastic injection made at one end of the tray to achieve reduces the production capacity

  potential of an injection molding machine with

  completed, to the extent that the course that the material is

2479-082

  obliged to go from one party to another to

  the impression in the mold and / or the high thicknesses required

  require extensive mold filling times

  first and then cool the room.

  The possibilities of injection molding machines are, in

  addition, also limited by the fact that it can not be

  only limited number of molds and, more generally,

a single footprint.

  Indeed, according to the known techniques, the impression on the mold is provided so that the large areas of

  the piece extend in the closing direction of the mold.

  This in itself implies the use of high power presses

  this to contain the thrusts in the closing direction

  mold, even when it has a single footprint.

  Thus, to use multi-cavity molds,

  It is necessary to provide presses of greater

  this again, which is not economical.

  It should be noted, moreover, that with the

  the injection process used until now, it is necessary that

  to form the cavity of the tray obtained is centered and locked in the mold, to avoid lurching at the time of

the injection of matter.

  It is therefore necessary to provide the mold with means for centering the punch, which means

  of course, to complicate the apparatus.

  In cases where there are provided means for locking the punch during injection, cold junction areas are formed in the walls of the container at the level of said means when they are removed. These areas may compromise the use of bins as they tend to create electrical problems as part of

the battery or the like.

  The use of conventional mussels also implies

  the need to extract the piece from the mold and to have, therefore, mechanical means capable of performing this function.

  Attempts have been made to obtain bins with the pre-

  cited and having smaller thicknesses by providing for the formation of the tray in two halves of molded "U" sections

  separately and joined together by welding techniques.

re appropriate.

  However, such bins are not only difficult to

  them to realize, but also economically not very advantageous. The main object of the present invention is

  on the contrary, to eliminate the disadvantages and disadvantages

  mentioned techniques and to enable the realization of

  one-piece containers with reduced wall thickness using

  fully developing the production capacities of

  jection of classic type and using molds of a

  simple structure with one or more

  two impressions, preferably and advantageously two or even more than two impressions, for the molding of several

parts simultaneously.

  The molding method according to the invention uses a mold with at least one impression and a punch intended for

  extend and be extracted from said footprint and is

  it consists in injecting plastic material

  than in the mold cavity at the level of at least two

  opposite sides of the tray to be obtained and at an in-

  intermediate between the bottom and the top of the tank.

  Thus, the plastic injection into the cavity in at least two opposite directions directed both transversely to the tray to obtain, or in directions perpendicular to the major axis of said tray to achieve.

  Always according to this product, we can perform the in-

  jection plastic material at a single point of each of the two opposite walls of the tray to obtain, or at several points of these walls separated in height, but still in

  the area between the bottom and the top of the tank.

  The injection of material thus carried out makes it possible to rapidly fill each impression of the mold, the path that the material must perform in order to achieve

  areas of the footprint furthest from the points of in-

  jection being, in any case, shorter than in the

anterior.

  This results in the possibility of reducing

  The thickness of the walls of the container obtained without ever compromising the rapidity and filling correction of the mold for obtaining appropriate bins. The reduction of the thickness itself implies a reduction in the cooling times of the injected material which, together with

  the speed of filling the mold allows you to take full advantage

  effectively and efficiently the production capacities of the

used injection.

  The injection of material carried out in at least two

  opposite directions directed transversely to the footprint

  The mold, and thus the punch for forming the cavity in the tray obtained, eliminates the need to guide and center the punch during injection. Indeed, the thrusts coming from the pressure of the material injected in opposite directions are themselves sufficient to ensure the correct centering of the

  punch. The conventional mechanical means are thus eliminated.

  centering the punch and, consequently, the inconveniences

  generated by the use of these means

  for the tray itself and its use.

  The invention also provides a mold for carrying out the process, which mold comprises two half-molds, one of which

  is fixed to one part of the fixed type and the other to a part

  bile of a molding press, the two half-molds having connecting surfaces located in a vertical plane and

  footprints delineating in combination with miniature punches

  corresponding bile with vertical extraction as many cavities which correspond by their shape and size to the tray to obtain which has two large walls, two small walls and a bottom, characterized in that the large walls of each cavity of the mold are parallel to the direction closing of the mold, while the small walls are perpendicular to

  said direction and parallel to the joint plane of the two half

  molds, the bottom of the tank being defined by a mold mold sector.

  lidaire of the moving part so that the mold being

  green, the resulting tray can fall freely

  withdrawal of the corresponding punch, at least one of the two half

  molds having at least one pair of casting channels

  singing in the cavity in opposite directions and at the level

  at least two opposite walls of the tray to obtain.

  Other features and advantages of the invention

  will emerge from the following detailed description

  with reference to the attached drawing given solely as an example

non-limiting ple.

  In the accompanying drawing FIG. 1 is a cross section of the closed mold,

  obtained in the plane of the casting channels of the plastic material

  tick or line I-I of Figure 2.

  Fig. 2 is a central section of the mold, according to

line II-II of FIG.

  Fig. 3 is an open mold section with the points

  are being extracted and the part being dumped,

falling by its own weight.

  Fig. 4 is an internal view of the mold in the con-

  as in Figure 3 and following arrows IV-IV

of the same figure 3.

  Fig. 5 is a perspective view of an example of

tray that can be obtained.

  The method described above essentially provides the embodiment by injection molding of a tray 10 affecting the section of a quadrilateral and having two large vertical walls 11, two small vertical walls 12 and a bottom 13,

  according to the representation of the drawing and in particular on the

5.

  This molding method uses, for example, a mold consisting of two elements or mold halves 1-2, one of which is fixed to the fixed part 3 and the other to the moving part 4 of a standard horizontal injection molding machine. , not shown here.

  Arrows A-B in Figure 1 indicate the directions

  closing and respectively opening the mold.

  The two mold halves 1-2 have indentations

  1'-2 'which delimit in combination between them and with a punch 5 can be removed vertically perpendicular to the closing directions and opening of the mold, a cavity whose shape and dimensions correspond to those of the tray

to achieve.

  In the accompanying drawing, there is shown a mold with two cavities and two punches for the simultaneous formation of two trays. However, the mold impressions could be in number sunprior to two or there could be one

  only, depending on the requirements, the power of the press used

  sée, etc. In all cases, each mold cavity is formed so that the large walls Il of the tank to be obtained are parallel to the direction of closure of the mold, while the small walls 12 are arranged perpendicularly to this direction, that is to say -Tell parallel to the joint plans

6 of the two halves.

  The bottom 13 of the tray is itself defined by a base sector 7 of the mold bound and movable with the movable half 2 (see Figure 3) and adapted to be inserted, when the mold is closed, in a corresponding housing 8 formed in

  half fixed in vertical alignment with the corre-

  and therefore with the punch corresponding to the said

  preinte. In the mold, in association with the imprint or each imprint, are formed the channels 9-9 'of casting of the plastic material which start from the injection nozzle 14 of the material and which open into said imprint in opposite directions and at an intermediate height between the bottom and

the edge of the bin to get.

  The casting channels 9-9 'provided for each

  may be two opposites one to the other

  as shown in Figures 1 and 2, without

  sometimes eliminate the possibility of multiple pairs

  opposite and possibly separated

  tor. In addition, the flow channels 9-9 'can lead to the large walls of the tray to obtain and / or at the level of smallparois. The casting of the hot runner-type casting material to at least two walls of the tray may comprise a conventional type of fastener (round, rectangular, etc.) or immersed, or tunnel self-cutting,

with or without carrot rejection.

  A mold of the type indicated has the advantage that the

  thrusts of the injected material corresponding to the large

  The kings in the room are contained and supported directly by the mold surfaces, while the small wall thrusts must remain supported by the power of the mold.

  closing of the press. As a result, equal power

  this press, it is possible, compared to the conventional technique

  and used previously, to arrange and use several impressions in the half-mold., which is all

  to the advantage of an increase in yield of said press.

  Controlled injection of material carried out in

  opposing on at least two opposite walls of the tray to be obtained guarantees an automatic and correct centering of the punch in the mold, without any need to resort to any means of

auxiliary centering.

  Thanks to the fact that the basic sector 7 forming the bottom of the tray can move with the movable half, it also has the advantage of automatic demolding of the tray, without the need to resort to extractors. Indeed,

  when the movable mold half 2 is away from the half

  fixed mold 1, below the molded tray, there are no

  so that the bag falls freely from its own weight

  while the punch 5 is moved upwards, as

  shown in FIGS. 3 and 4 of the drawing, the displacement towards

  the top of the container being generally prevented by the effective blocking

  killed by an insert 15 provided in the mold for guiding

of the punch.

  The mold described above has the advantage that the

  simple insertion of wedges 16 of different heights and appro-

  required in the cavity of the mold (see Figure 2) allows to obtain bins of various heights and this without the need to disassemble the mold or change the structure

  overall, which is necessary with the molds of

than earlier.

  The molding method and the mold described allow

  attempt to injection mold plastic bins

  walls of reduced thickness, the time of

  -35 lage being reduced even if one uses presses with low power of closure, the production thus being increased

and the reduced cost.

  Of course, the invention is not limited to the embodiment which has just been described and which has been shown

  attached drawings. Many modifications can be made

  details without departing, for that, from the framework of the

present invention.

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Claims (5)

R E V E N D I C A T IO N S   1 - Process for injection molding plastic containers, in particular for battery and electric accumulators, and in which a mold (1) is used with at least one impression and a punch (5) intended to expand and to be extracted from said fingerprint, characterized in that   that it consists in injecting plastic material into the   preint of the mold at at least two side walls   oppositions (11) of the container (10) to be obtained and at a height between   mediate between the bottom (13) and the top of the tray.   2 - Method according to claim 1, characterized in that the plastic injection is carried out in the cavity of the mold, in at least two opposite directions (9-9 ') both directed transversely to each other. to the tray (10) to be obtained, in directions perpendicular to the major axis of the tray (10) and the punch (5) for forming the cavity in said tray (10).   3 --Procédé, according to claim 1, characterized in that one carries out the injection of plastic material into the mold cavity at a single point (9-9 ') of each of the   less-two opposite walls of the tank (10) to obtain.   - 4 - A method according to claim 1, characterized in that one carries out the injection of plastic material into the cavity of the mold simultaneously at several points of each of at least two opposite walls of the tray   to obtain, these points being offset in height.     - Process according to claim 1 and one   any of claims 2 to 4, characterized in that   the material injection is carried out in two opposite directions of at least two side walls by casting, with heat, with   classic or submerged tie, or tunnel. -   6 - perfectlonn6 mold for implementing the molding process according to claim 1 and or one   any of claims 2 to 5, and comprising two half   molds (1-2), one of which is fixed to a part of the fixed type (3) and the other to a movable part (4) of a molding press,   the two half-molds (1-2) having connecting surfaces   located in a vertical plane and footprints delimiting   both in combination with movable punches (5) corresponding to   upright extraction units, as many cavities as correspon-   tooth by their shape and dimensions to the tray (10) to obtain   which has two large walls (11), two small walls   (12) and a bottom (13), characterized in that the large walls (11) of each mold cavity are parallel to the   direction of closure of the mold, while small   kings (12-) are perpendicular to the said direction and   leles to the joint plane of the two demi-molds, the bottom of the tray (13) being defined by a-sector (7) of the mold integral with the movable part so that J. the mold open, the tray obtained   can fall freely vero I down, when withdrawing the pon-   corresponding section (5), one of the two half-molds (1-2) presents at least one. number of channels of castings (9-9 ') opening into the cavity in opposite directions and at   level of at least two opposite walls of the tray (10) to obtain.   7 - Noule, according to claim 6, characterized   in that it comprises at least one removable insertion (15) of   to be fixed in one, in the self, in the cavities, for   specify the height of the tank (10) to be obtained. N f y