FR3072591A1 - MOLD FOR MANUFACTURING RIBBED PIECE AND CORRESPONDING METHOD - Google Patents

Abstract

The mold (1) comprises first and second half-molds (21, 23), first and second inner surfaces (27, 29) of the first and second half-molds (21, 23) being respectively provided to form the front faces and rear (5, 7) of the ribbed piece (3); the second half-mold (23) has a main part (31) and an ejector (33), the ejector (33) having a body (34) having an end surface (35) defining part of the second internal surface ( 29) and a side surface (37) provided to form one side of the rib (9) of the workpiece (3); the ejector (33) has a slider (47) movable relative to the body (34) between an extended position in which a first end (49) of the slider (47) projects from the side surface (37), and a retracted position in which the first end (49) of the slider (47) is retracted into the body (34).

Description

Mold for manufacturing a ribbed part and corresponding process

The invention generally relates to the manufacture by molding of ribbed parts.

More specifically, the invention relates in a first aspect to a mold for manufacturing a ribbed part, the ribbed part comprising a front face, a rear face and a rib formed on the rear face.

Such parts can for example be manufactured in a mold, one of the two half-molds of which has a movable ejector. The ejector has a lateral surface intended to form one side of the rib, the other side of the rib being formed by an internal surface of the half-mold.

The part is generally ejected by moving the ejector relative to the main part of the half-mold in a direction which can be parallel to the rib.

A particular problem arises when the rib has a hole formed during the molding step. In this case, it is possible to provide a relief on the lateral surface of the ejector, thus reserving a volume which will create the hole once the part has left the mold.

In this case, during the ejection of the part, it is possible to provide for the ejector to move both upwards, that is to say parallel to the plane of the rib, and laterally in s' spreading from the rib so as to disengage the relief from the hole.

Such a movement is known by the English name "up and away", or even inclined rising wedge. This movement is not possible when the part has a shoulder preventing the ejector from moving laterally from the rib.

In this context, the invention aims to propose a manufacturing mold for manufacturing such parts.

To this end, the invention relates to a mold for manufacturing a ribbed part, the ribbed part comprising a front face, a rear face and a rib formed on the rear face, the mold comprising first and second half-molds, movable relative to each other between a closed position in which the first and second half-molds are relatively closer to each other and delimit between them a mold cavity, and an open position in which the first and second half-molds are relatively more distant from each other;

first and second internal surfaces of the first and second half-molds being provided respectively to form the front and rear faces of the part;

the second half-mold comprising a main part and an ejector movable relative to the main part in an ejection direction, the ejector having a body having a terminal surface defining a part of the second internal surface and a lateral surface provided for form one side of the rib;

the ejector comprising a slide movable relative to the body between an extended position in which a first end of the slide projects from the lateral surface, and a retracted position in which the first end of the slide is retracted into the body.

In the molding step, that is to say when the material constituting the ribbed part is introduced into the molding cavity, the slide is in the extended position. This creates a hole in the rib of the part.

To eject the part, the front end of the slider is retracted in the body of the ejector, either concomitantly or after moving the ejector. It is thus possible to provide for the ejector a rectilinear displacement, typically substantially parallel to the rib. It is no longer necessary to provide for the ejector an additional lateral movement of spacing with respect to the rib.

As a result, the manufacturing mold can be used to make all kinds of parts, including parts with a shoulder that would prevent the ejector from moving transversely from the rib.

The manufacturing mold may also have one or more of the characteristics below, considered individually or in any technically possible combination:

- the normal to the lateral surface forms with the direction of ejection an angle between 60 ° and 120 °;

the terminal surface has first and second zones connected to each other by a shoulder turned in a direction opposite to the lateral surface, the normal to the shoulder forming with the normal to the lateral surface an angle between 91 ° and 179 °;

- the first and second zones are offset from one another in the direction of ejection;

- The slide moves between its extended and retracted positions in a direction of movement forming with the normal to the lateral surface an angle between -30 ° and + 30 °;

- The body comprises a cavity in which the slide is housed free in translation relative to the body;

- The ejector comprises an elastic member urging the slide towards its retracted position;

- the ejector moves relative to the main part of the second half-mold between a molding position and an ejection position, the second half-mold comprising a drive mechanism forcing the slide in the extended position when the ejector is in the molding position;

- the drive mechanism comprises a cam surface formed on the main part of the second half-mold, a second end of the slider forming a cam follower and cooperating with the cam surface to force the slider into the extended position when the ejector is in the molding position.

According to a second aspect, the invention relates to a method for manufacturing a ribbed part comprising a front face, a rear face and a rib formed on the rear face, using a mold having the above characteristics:

- placing the first and second half-molds in the closed position, the slide being in the extended position;

- introduction of a material into the mold cavity, the first end of the slide forming a hole in the rib;

- placing the first and second half-molds in the open position;

- ejection of the part by displacement of the ejector relative to the main part of the second half-mold and by displacement of the slide from the extended position to the retracted position.

Other characteristics and advantages of the invention will emerge from the detailed description which is given below, by way of indication and in no way limitative, with reference to the appended figures, among which:

- Figure 1 schematically illustrates the manufacturing mold of the invention in the open position in a sectional view;

- Figure 2 illustrates the mold of Figure 1, in the closed position, after injection of the ribbed part in a sectional view; and

- Figure 3 shows the second half-mold, after moving the ejector in a sectional view.

The mold shown in Figures 1 to 3 is intended for the manufacture of a ribbed part of the type shown in Figures 2 and 3. The ribbed part 3 has a front face 5, a rear face 7 and a rib 9 formed on the back side. The rib 9 has a hole 11.

The part 3 comprises a first part 15, a second part 17 and a shoulder 19 connecting the first and second parts 15 and 17 to each other. The rib 9 is formed on the first part 15. The second part 17 of the part 3 is offset towards the rear of the part with respect to the first part 15. Thus, the rear of the shoulder 19 is located in screw opposite, in a first direction T, of the rib 9.

The rib 9 extends from the rear face 7 in a second direction L, materialized by the arrow L in Figures 1 to 3. The first direction is materialized by the arrow T in Figures 1 to 3. In the example shown, the rib 9 extends in a plane perpendicular to the first direction.

The manufacturing mold is typically an injection mold. As a variant, it is of any other type.

The mold 1 comprises first and second half-molds 21, 23, visible in particular in FIG. 1. The first and second half-molds 21, 23 are movable relative to each other between a closed position in which the first and second half-molds 21, 23 are relatively closer to each other, and an open position in which the first and second half-molds 21, 23 are relatively more distant from each other. The open position is shown in Figure 1. The closed position is shown in Figure 2.

Typically, the first and second half-molds 21, 23 move between their open and closed positions by a movement in the second direction which is here longitudinal.

In the closed position, the first and second half-molds 21, 23 define between them a molding cavity 25.

Typically, the mold cavity 25 has the shape of the part 3 to be manufactured.

More specifically, the first and second half-molds, 21 and 23, have respective first and second internal surfaces 27, 29 provided to respectively form the front 5 and rear 7 faces of the part 3. In the closed position, the first and second internal surfaces 27 and 29 are opposite one another and delimit almost all of the molding cavity.

As visible in the figures, the second half-mold 23 has a main part 31 and an ejector 33 movable relative to the main part 23 in an ejection direction E.

The hole 11 is typically through. As a variant, it is blind, and open on one side 13 of the rib 9 facing the ejector which is to the right in the representation of FIG. 3.

The ejector 33 moves in translation, exclusively in the direction of ejection. This direction of ejection is for example parallel to the second direction.

The ejector 33 has an end surface 35 defining a part of the second internal surface 29, and a lateral surface 37 provided to form one side of the rib 9.

The terminal surface 35 has first and second zones 39, 41, connected to each other by a shoulder 43. The shoulder 43 forms a non-zero angle with respect to the first and second zones 39 and 41. The first and second zones 39, 41 are provided to partially form parts 15 and 17 on a rear side. The shoulder 43 is provided to form the shoulder 19 of the part, on a rear side.

The first and second zones 39, 41 are offset from one another in the direction of ejection. The second zone 41 is set back from the first zone 39 in the direction of ejection. The different orientations of the lateral surface 37, of the first and second zones 39 and 41 and of the shoulder 43 do not allow the part 3 to move perpendicular to the direction of ejection in the ejection position of the ejector 33.

Typically, the normal N1 at the shoulder 43 forms with the normal N2 at the lateral surface 37 an angle a1 between 91 ° and 179 °.

Furthermore, the normal N2 at the lateral surface 37 forms with the direction of ejection E an angle comprised a2 between 60 ° and 120 °, preferably comprised between 80 ¹ and 100 °. In one embodiment, the normal N2 at the lateral surface 37 forms with the direction of ejection E an angle a2 of 90 °.

Thus, the ejector 33 has a projecting part 45, delimited by the lateral surface 37, the shoulder 43 and the first zone 39, intended to form the hollow zone delimited on the rear face of the part between the first part 15 , the rib 9 and the shoulder 19.

This projecting part 45 projects with respect to the second zone 41 in the direction of ejection.

The ejector 33 also comprises a slide 47, movable relative to the body 34 between an extended position (FIGS. 1 and 2) in which a first end 49 of the slide 47 projects relative to the lateral surface 37, and a position retracted into which the first end 49 of the slide is retracted into the body 34.

The first end 49 is intended to form the hole 11 of the rib 9. It has any suitable shape: circular, rectangular, etc.

Typically, the slide 47 moves between its extended and retracted positions in a direction of movement D forming with the normal N2 at the lateral surface 37 an angle between -30 ° and + 30 ° preferably an angle between -10 ° and 10 °.

In one embodiment, the slide 47 moves between its extended and retracted positions in a direction of movement forming with the normal N2 at the lateral surface 37 a zero angle.

The body 34 comprises a cavity 51 in which the slide 47 is housed.

The slide 47 is free in translation inside the cavity 51 relative to the body 34.

The ejector 33 also comprises an elastic member 53, urging the slide 47 towards its retracted position. The elastic member 53 is of any suitable type. In the example shown, the elastic member 53 is a compression spring.

The cavity 51 is substantially rectilinear. It passes through the ejector 34 right through. It comprises a central section 55 of relatively larger section, extended on either side by two end sections 57 of relatively smaller sections. The end sections 57 are through. One of the sections 57 opens at the lateral surface 37. The other end section 57 opens on an inclined surface 59, located opposite the lateral surface 37.

At each of its two opposite ends, the central section 55 has an annular surface 61, perpendicular to the central axis of the cavity 51. The annular surfaces 61 connect the peripheral wall of the central section 55 to the peripheral walls of the end sections 57 .

The elastic member 53 bears on one side on a flange 63 rigidly fixed to the slide 47, and on the other side on the annular surface 61 facing towards the lateral surface 37.

As visible in the figures, the ejector 33 moves relative to the main part 31 of the second half-mold between a molding position and an ejection position. The molding position is shown in Figures 1 and 2. The ejection position is shown in Figure 3. The ejector moves between its two positions in the direction of ejection, as shown above.

To do this, the main part 31 has a channel 65 in which the ejector 33 is engaged. The channel 65 has a surface 67 placed facing the lateral surface 37 when the ejector 33 is in its molding position. The surface 67 is provided to form, with the lateral surface 37, the rib 9 of the part 3.

In the molding position, the end surface 35 is inscribed in the second internal surface 29. The ejector 33 is retracted inside the channel 65.

In the ejection position, the ejector 33 projects out of the channel 65, towards the molding cavity which is upwards in the representation of FIG. 3. The end surface is offset from the rest of the second internal surface 29, following the direction of ejection. The cavity 51 and the slide 47 are located outside the channel 65. Likewise, the lateral surface 37 is located outside the channel 65. The inclined surface 59 is also located outside the channel 65.

Furthermore, the second half-mold 23 includes a drive mechanism 69 forcing the slide 47 into its extended position when the ejector 33 is in the molding position.

The drive mechanism 69 is arranged to place the slide 47 in its retracted position when the ejector 33 passes from its molding position to its ejection position.

The slide 47 is driven to do this by the elastic member 53.

As can be seen in particular in FIG. 3, the drive mechanism 69 comprises a cam surface 71 formed on the main part 31 of the second half-mold 23, a second end 73 of the slide 47 forming a cam follower and cooperating with the cam surface 71 to force the slide 47 in the extended position when the ejector 33 is in the molding position.

In the example shown in the figures, the cam surface 71 is formed in the wall delimiting the channel 65. The cam surface 71 moves away from the ejector 33 in the first direction when it is followed towards the second internal surface 29 in the second direction.

In the molding position, the inclined surface 59 is in contact with the cam surface 71. The two surfaces have the same shape, and the same inclination.

As visible in FIG. 3, in the ejection position, the second end 73 of the slider projects in the first direction out of the cavity 51, at the level of the inclined surface 59. The elastic member 53 presses on the flange 63 and biases it in the first direction until it comes to bear on the annular surface 61 facing the inclined surface 59. This causes the second end 73 to exit. In this position, the first end 49 of the slide is retracted inside the cavity 51.

On the contrary, when the ejector 33 is in its molding position, the cam surface 71 forces the second end 73 of the slider to enter the cavity 51. The slider 47 is therefore forced to move in the first direction towards the surface lateral 37, against the restoring force of the elastic member 53. As a result, the flange 63 takes off from the annular surface 61. This movement causes the exit of the first end 49 of the slide.

The method of manufacturing the ribbed part 3 using the mold 1 described above will now be detailed.

In the initial state, the two half-molds 21, 23 are in the open position.

The process includes the following steps:

-placement of the first and second half-molds 21, 23 in the closed position, the slide 47 being in the extended position;

- introduction of a material into the molding cavity 25, the first end 49 of the slide 47 forming the hole 11 in the rib 9;

- placing the first and second half-molds 21, 23 in the open position;

- Ejection of the part 3 by displacement of the ejector 33 relative to the main part 31 of the second half-mold 23 and by displacement of the slide 47 from the extended position to the retracted position.

In the initial state, the ejector 33 is in its molding position. The drive mechanism 69 causes the slide 33 to be in its extended position.

During the step of introducing the material into the molding cavity 25, the material will disperse and occupy the entire volume of the molding cavity 25. It flows until it comes to surround the first end 49 of the slide, as illustrated in the figure

2.

In the step of ejecting the part 7, the ejector 33 moves in translation in the direction of ejection, that is to say in the second direction in the example shown. It drives the part 3 with it, this part peeling off from the main part 31 of the second half-mold 23. Due to this movement of the ejector 33 relative to the main part 31, the inclined surface 59 of the ejector 33 detaches from the cam surface 71. Under the effect of the stress on the elastic member 53, the slide 47 is then moved to its retracted position. The first end 49 of the slide 47 is extracted from the hole 11. It is then possible to grasp the part 3 and separate it from the ejector 33 by moving the part 3 in the direction of ejection. The shoulder 19 of the part does not prevent this movement.

The mold and process described above have multiple advantages.

They make it possible to manufacture in a simple manner parts having a shoulder such as the shoulder 19 described above, which prevents the displacement of the ejector in the first direction making it possible to disengage this ejector from the hole 11 in the rib.

The fact of housing the slide in a body cavity makes the device particularly compact.

The use of an elastic member urging the slide towards its retracted position makes the process particularly simple.

The fact that the slide is moved into the extended position by a cam surface formed on the second half-mold also makes the device particularly simple mechanically.

The mold and the corresponding manufacturing process can have multiple variants.

The mold and the method can be designed to produce ribbed parts not having a shoulder such as the shoulder 19 described above.

The slider can be driven between its retracted and extended positions by other means than those described above. In particular, it is possible to provide a groove in the main part of the second half-mold, the rear end of the slide forming a dovetail driven in the first direction by the groove when the ejector moves to its position of ejection.

The material constituting the ribbed part can be of any type. This material is a plastic material, or a metal, or any other suitable material.

Claims (10)

1, -Manufacturing mold (1) of a ribbed part (3), the ribbed part (3) comprising a front face (5), a rear face (7) and a rib (9) formed on the rear face ( 7), the mold (1) comprising first and second half-molds (21, 23), movable relative to each other between a closed position in which the first and second half-molds (21, 23) are relatively closer to each other and delimit between them a mold cavity (25), and an open position in which the first and second half-molds (21,23) are relatively more distant from one another. 'other; first and second internal surfaces (27, 29) of the first and second half-molds (21, 23) being provided respectively to form the front and rear faces (5, 7) of the part (3); the second half-mold (23) comprising a main part (31) and an ejector (33) movable relative to the main part (31) in an ejection direction, the ejector (33) having a body (34) having a terminal surface (35) defining a part of the second internal surface (29) and a lateral surface (37) provided to form one side of the rib (9); the ejector (33) comprising a slide (47) movable relative to the body (34) between an extended position in which a first end (49) of the slide (47) projects relative to the lateral surface (37), and a retracted position in which the first end (49) of the slide (47) is retracted into the body (34). 2, - Mold according to claim 1, wherein the normal to the lateral surface (37) forms with the direction of ejection an angle between 60 ° and 120 °. 3, - Mold according to any one of the preceding claims, in which the terminal surface (35) has first and second zones (39, 41) connected to one another by a shoulder (43) turned in a direction opposite the lateral surface (37), the normal (N1) at the shoulder (43) forming with the normal (N2) at the lateral surface (37) an angle (cry) between 91 ° and 179 °. 4, - A mold according to claim 3, wherein the first and second zones (39, 41) are offset from one another in the direction of ejection. 5, - Mold according to any one of the preceding claims, in which the slide (47) moves between its extended and retracted positions in a direction of movement forming with the normal (N2) at the lateral surface (37) an angle included between -30 ° and + 30 °. 6. - Mold according to any one of the preceding claims, in which the body (34) comprises a cavity (51) in which the slide (47) is housed free in translation relative to the body (34). 7. - Mold according to any one of the preceding claims, in which the ejector (33) comprises an elastic member (53) urging the slide (47) towards its retracted position. 8. - Mold according to any one of the preceding claims, in which the ejector (33) moves relative to the main part (31) of the second half-mold (23) between a molding position and a position of ejection, the second half-mold (23) comprising a drive mechanism (69) forcing the slide (47) in the extended position when the ejector (33) is in the molding position. 9. - A mold according to claim 8, in which the drive mechanism (69) comprises a cam surface (71) formed on the main part (31) of the second half-mold (23), a second end (73) of the slide. (47) forming a cam follower and cooperating with the cam surface (71) to force the slide (47) into the extended position when the ejector (33) is in the molding position. 10. - Method for manufacturing a ribbed part (3), the ribbed part (3) comprising a front face (5), a rear face (7) and a rib (9) formed on the rear face (7), using a mold (1) according to any one of the preceding claims, the method comprising the following steps: - placing the first and second half-molds (21, 23) in the closed position, the slide (47) being in the extended position; - introduction of a material into the mold cavity (25), the first end (49) of the slide (47) forming a hole (11) in the rib (9); - placing the first and second half-molds (21, 23) in the open position; - ejection of the part (3) by displacement of the ejector (33) relative to the main part (31) of the second half-mold (23) and by displacement of the slide (47) from the extended position to the retracted position .