FR2899511A1 - Device for cutting injection core from plastics injection molding, e.g. vehicle bodywork strip, comprises movable cutter actuated in synchronization with movement of pattern during demolding - Google Patents

Abstract

A device for cutting an injection core (8) connected via a sill to a plastics injection molding (1), in a mold (28) having a pattern (27) and a matrix (33), is located in the mold and comprises a movable cutter (14) near the injection zone. The cutter does not affect injection in a molding position, and can be actuated to move into the sill section in synchronization with movement of the pattern during demolding. An independent claim is included for the corresponding injection mold, provided with at least one injection core cutting device as above.

Description

The present invention relates to a cutting device in the mold,

  the injection core of a molded part, simultaneously with the opening of the mold.

  The invention also relates to an injection mold equipped with at least one such injection core cutting device. The invention applies preferentially to the injection molding of rods, moldings, belt lining or rocker covers for road vehicles, or any other elongated piece for the automobile or other. More generally, it can be applied to the injection molding of any part to be freed of its injection core before use. In many fields and for example in the automotive field, plastic parts obtained by an injection molding process are commonly used. To achieve such a molding, using a mold formed of two parts, a lower part called punch and an upper part called matrix. When the mold is closed, its two parts arranged one on the other delimit between them a molding cavity whose shape corresponds to the piece to be molded. The hot and liquid plastic material is injected under pressure into this cavity so as to fill and form, after cooling and demolding, the desired part. To allow the liquid plastic material to enter the mold, there is in the lower part an open feed zone which communicates with a small tank in which the hot material is distributed before spreading inside the mold. After cooling and demolding the

  part, there is a block of material bound to the molded part and corresponding to the material present at the end of the molding in the feed tank. This block of material, commonly called injection core because of its shape in the old tools, must be cut out of the mold outlet to keep only the desired injected part. The shape and size of this injection core depend on those of the molding.

  For elongated and narrow molded parts, such as, for example, the protective or embellishing strips of the automobile body, it is preferable to use an injection core in the form of a sheet, that is to say of thin thickness on a surface. certain length, to feed the cavity of the mold of molten plastic material. The injection core is then called injection ply or supply ply. For large length parts, it is possible to use two or three injection plies, or more, spread over the length of the part to perform a multipoint injection, sequenced or not. After removing the piece from its mold, it is essential to cut and remove the carrot or injection sheet attached to it before being able to proceed to the subsequent step of making the piece, its packaging or its set up in use position.

  This intermediate step is currently performed by means of complicated and expensive automated machines. Indeed, a robot must first grasp the pieces, which are usually gathered by cluster of several molded parts simultaneously. He puts them in a complex automated device, allowing after indexing, the cutting of carrots or tablecloths

  injection. Once the cut is made, the robot proceeds to evacuate the molded parts. The object of the invention is to eliminate this intermediate step which represents a significant additional cost in the manufacturing process. For this and according to the invention, the cutting of the feed carrot is carried out directly in the injection mold. The cutting operation occurs during demolding, synchronized with the opening of the mold. According to a preferred variant of the invention, the displacement of the punch automatically and simultaneously causes the cutting of the injection core.

  To achieve such an objective, the invention provides a device for cutting an injection core connected by a connecting portion called threshold to a plastic part, in particular a protective strip or embellishment vehicle body, injection molded by means of a mold comprising a punch and a die. According to the invention, the cutting device is located in the injection mold. It comprises a movable knife disposed near the injection zone, which in the molding position does not interfere with the injection operation, and a means for actuating the moving knife which causes movement of the movable knife leading to the severing the threshold of the injection core synchronously with the movement of the punch during demolding. According to a preferred embodiment of the invention, the actuating means of the movable knife enters into operation automatically at the opening of the mold by the movement of the punch, simultaneously or with a delay relative to this displacement. The means for actuating the moving knife

  preferably comprises at least one inclined finger cooperating with an inclined bore. This inclined finger can be part of or be secured to the matrix. Advantageously, it may have a diameter substantially equal to or less than the diameter of the corresponding inclined bore. The invention also provides an injection mold comprising a punch and a die, for use in the injection molding of a plastic part, in particular a vehicle body protection or embossing strip, and equipped with at least one cutting device of an injection core according to the invention. Other features and advantages of the invention will appear on reading the detailed description which follows, description made with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a rod, taken as a descriptive example, out of a mold according to the prior art before cutting of its injection core; . Figure 2 is a top view in perspective of a first embodiment of a cutting tool according to the invention; . Figure 3 is a perspective view of a portion, located at an injection point, of the punch portion of a mold equipped with the cutting device of Figure 2; . Figure 4 is a schematic cross-sectional view at an injection point of a mold equipped with the cutting device of Figure 2 before demolding and cutting the core; . Figure 5 is a schematic cross-sectional view at an injection point of a mold equipped with the cutting device of Figure 2 after cutting the core, the punch part has moved slightly;

  . FIGS. 6 to 10 are views diagrammatically illustrating the principle of displacement of the cutting tool of FIG. 2 by means of inclined fingers; FIGS. 6 and 7 correspond to a variant with immediate displacement of the cutting tool; and - Figures 8 to 10 correspond to a variant with delay in the displacement of the cutting tool; . Figures 11 to 13 are top views schematically illustrating the principle of displacement of another rotary cutting variant of a cutting tool according to the invention; . FIG. 14 is a perspective view of a portion, located at an injection point, of the punch portion of a mold equipped with another embodiment of the cutting device according to the invention in position. molding; . Figure 15 is a schematic cross-sectional view at an injection point of a mold equipped with the cutting device of Figure 14 before demolding and cutting the core; . Figure 16 is an isolated schematic front view of the cutting tool of the cutting device of Figure 14 and its drive means, in a configuration corresponding to Figure 15; . Figure 17 is a schematic cross-sectional view at an injection point of a mold equipped with the cutting device of Figure 14 after cutting the core, the punch part has moved slightly; . FIG. 18 is an isolated schematic front view of the cutting tool of the cutting device of FIG. 14 and its drive means, in a configuration corresponding to FIG. 17.

  The cutting device according to the present invention will now be described in detail with reference to Figures 1 to 18. The equivalent elements shown in the different figures will bear the same reference numerals. In Figure 1, there is shown a molded part 1 made of plastic material, produced by an injection molding process. According to a preferred example of application of the invention, the molded part 1 shown is a strip 2 of the automobile body belt. Nevertheless, it should be understood that the invention can be applied to the cutting of the injection core of any other molded plastic part, whatever its nature. For the purpose of descriptive simplification, the molded part 1 will be called rod in the remainder of this description, without any limitation being sought. In the same way, the core or the injection or feeding layer will be called the injection core. The rod 2 shown is an elongated piece which has a convex convex outer face 3, visib = the when the rod is mounted, and an inner face 4 concave. It thus defines on the side of its inner face 4 a hollow interior longitudinal space 5, which typically contains a number of fastening means 6 for mounting the rod in the use position on the body of a vehicle. These fixing means 6 are here, for example, integral fixing clips 7, integrally molded with the inner face 4 of the rod 2.

  Nevertheless, these fixing means 6 could obviously be reported clips. This rod 2 has been molded according to a

  injection technique in a conventional mold not being equipped with a cutting device according to the invention. After cooling and demolding, this rod 2 thus has a solidified injection core 8, attached to its lower edge 9. This core 8 is in the form of an elongated sheet 10, connected to the edge 9 by a connecting zone of much finer section called threshold 11. The web 10 is extended on the other side by a narrower portion 12 whose shape corresponds to that of the feed channel. As indicated in the introductory part, the rod 2 may comprise one or more other injection cores 8, similar or of different sizes and / or shapes, preferably distributed along its lower edge 9. In the example shown, the injection core 8 extends conventionally in the extension of the rod 2, that is to say substantially in the longitudinal plane of the rod. To be compatible with the cutting device according to some embodiments of the invention, the injection core 8 must instead be provided downward, in a plane substantially perpendicular to the plane of the rod, as can be seen for example on In this case, the injection mold must be designed taking into account this technical requirement.

  The cutting device according to the invention comprises a cutting tool 13, a first embodiment of which has been shown alone in FIG. 2. According to this preferred variant, the cutting tool 13 comprises a knife 14 which is movable in translation. The knife 14 is preferably fixed at each of its ends 17 to a guide arm 15.

  The knife 14 comprises for this purpose a bearing strip 16, the two end portions 17 of which bear against the respective rear end portions 18 of the two guide arms 15. The knife 14 is fixed at this level by a any suitable fastening means 19, for example by screwing. The support strip 16 is extended in the central portion by a blade 20 which extends substantially horizontally forwards, that is to say in the direction of the front ends 21 of the guide arms 15 not supporting the web. 16. The upper face 22 of the knife 14 is substantially flat so as to be able to perfectly level the plastic still a little hot and relatively soft at the beginning of the demolding operation. The blade 20 terminates in a cutting edge 23 formed of a thin end extended downwards by a bevelled edge 24.

  The blade 20 may have a variable width which depends on the applications, but must be sufficient to correctly cut the target injection core 8. The example shown is intended to cut an injection core 8 into a sheet 10. The blade 20 is relatively wide. It thus gives the knife 14 a general shape substantially T-shaped with an enlarged base. The guide arms 15 are preferably formed of two elongate and substantially parallelepipedal base blocks 25 extended downwardly by a longitudinal guide extension 26 with a preferably substantially dovetail section. These extensions 26 are intended to slide in grooves of complementary section shape, formed in the punch portion 27 of an injection mold 28. The preferred form dovetail allows particularly precise guidance of

  the cutting tool 13 during its movements. According to the embodiment shown in Figures 2 to 10, each guide arm 15 may also comprise, near its front end 21, an inclined bore 29 opening through an opening 30 of substantially circular shape, in the upper face 31 of its base block 25. These inclined ducts 29 are designed to cooperate with inclined fingers 32 belonging or secured to the matrix portion 33 of the injection mold 28 by any suitable means, so as will be seen by the subsequently, to serve as means for actuating the knife 14 and thus to cause its movement simultaneously with the opening of the mold.

  As can be seen in FIGS. 3 to 5, the punch portion 27 of the mold 28 comprises in the injection zone a part that will be called an injection shoe 34 in which a supply reservoir 35 communicating by an open feed zone 36 with the inside of the mold 28. As explained above, the injection core 8 is formed by the plastic material which at the end of the molding solidifies inside this feed tank 35 .

  In use, the cutting tool 13 is positioned at the injection zone, its guide arms 15 extending on either side of the injection shoe 34 and its knife 14 resting in a cavity 37 of appropriate form formed in the upper part of the injection shoe 34. To allow the mounting of the cutting tool 13 and that of the injection shoe 34, a removable element 38 of the punch 27 is put in place that a once the assembly is completed to complete the molding form. This removable element 38 rests on the upper face of the injection shoe 34 and the tool of

  cutout 13, but allows the functional movement of the latter. It further allows access thereafter to the injection shoe 34 and the cutting tool 13 for possible maintenance or replacement.

  During the molding operation illustrated in FIG. 4, the injection mold 28 is closed. The punch 27 is in abutment against the matrix 33 which is fixed. The cutting tool 13 is then in the retracted molding position.

  In this position, the knife 14 is near or preferably in abutment against the rear edge 39 of the cavity 37 of the injection shoe. Its upper face 22 is flush with that of the injection shoe 34, the guide arms 15 and the adjacent portion of the punch 27 and thus extends the lower molding face. Due to the retracted position of the cutting tool 13, the cutting edge 23 of the knife 14 is not in contact with the facing wall of the matrix and thus leaves open the open feed zone 36. The presence in the mold of the cutting tool 13 does not interfere with the supply and causes no discomfort during the injection. Once the injection is complete and after cooling; of the plastic, demolding begins with a progressive movement of the punch 27 as shown in Figure 5. The rod 2 remains on the punch 27 to proceed to a subsequent release of the pockets.

  The displacement of the punch 27 causes, by means of the actuating means, a simultaneous translational movement of the cutting tool 13. This movement is guided by a sliding of the longitudinal guide extensions 26 of the arms 15 of the tool in the corresponding grooves of the punch 27. The knife 14 moves towards the outside of the mold and cuts the threshold 11 of the carrot

  Injection 8. Cutting is easy because the plastic is still a bit hot and therefore relatively soft. Thanks to the lateral guidance of the cutting tool in the grooves of the punch 27, and even vertical with the preferred dovetail shape of the longitudinal guide extensions 26, the cut is very precise. This guidance also guarantees the reproducibility of the cutting operation.

  The knife 14 comes from its upper face 22 to flatten the plastic material of the edge of the rod 2 and cut by its cutting edge 23 the threshold 11 of the core 8 which is substantially perpendicular thereto. The lower edge 9 of the rod 2 is thus left perfectly clean and without any burrs. The displacement of the cutting device according to the invention is synchronized with the displacement of the punch 27 so that the cutting edge 23 does not abut in the die 33 at the end of the stroke. However, the cutting preferably occurs at the beginning of the movement of the punch 27 so that the die 33 can still hold the rod to avoid deformation of the still slightly hot material during the cutting operation.

  The displacement of the cutting tool 13 may be controlled by any appropriate actuating means slaved or coordinated with the movement of the punch, for example by means of servomotors, cylinders or other.

  According to a preferred embodiment, this displacement can advantageously be caused by a system of inclined fingers 32 cooperating with the inclined bores 29 of the guide arms 15 of the cutting tool.

  The operating principle of this actuating means has been shown schematically in FIGS. 6 to 10.

  In each inclined bore 29 of the guide arms 15 of the cutting tool 13 is inserted the end of a finger 32 inclined in the same way. This finger 32 belongs, is connected or secured by any suitable means to the matrix portion 33 of the injection mold. When the punch 27 moves to demold, the bore 29 also moves jointly, substantially vertically according to the arrow 40. The fixed and inclined finger 32, being in this bore 29, consequently causes a substantially horizontal displacement according to the arrow 41 of the corresponding guide arm 15. The cutting tool 13 thus advances a distance d, sufficient for the blade 20 of the knife 14 can cut the threshold 11 of the injection core 8.: When the inclined finger 32 has a slightly smaller diameter but substantially equal the diameter of the inclined bore 29, as in the variant of Figures 6 and 7, the displacement of the cutting tool 13 is immediate and simultaneous to that of the punch 27. In some cases, it may be advantageous that the movement of the cutting tool 13 is performed with a certain delay with respect to the displacement of the punch 27, for example to ensure that the cutting edge 23 does not abut in the matrix at the end of the stroke. The cutting device according to the invention advantageously makes it possible to obtain this delay in a very simple manner as illustrated in FIGS. 8 to 10. Of course, such a delay can be obtained by any other means imaginable by those skilled in the art. FIGS. 8 to 10 show an embodiment of a cutting tool 13 according to the invention in which the inclined fingers 32 have a diameter smaller than that of the bores.

  inclined 29 correspondents. In the molding position shown in FIG. 8, the inclined finger 32 bears against the rear edge 42 of the inclined bore 29.

  Once the molding is finished and after a certain cooling time, the punch 27 starts to move away, which induces a downward movement, substantially vertical, of the inclined bore 29, symbolized by 1.a arrow 40.

  In a first phase, which lasts until the inclined finger 32 comes into abutment against the front edge 43 of the inclined bore 29 as shown in Figure 9, the cutting tool 13 remains stationary. In a second step and while the punch 27 has already moved a little, the continued movement of the punch 27 and therefore the joint movement of the inclined bore 29 along the arrow 40 causes, under the effect of the finger 32, a displacement towards the front of the cutting tool 13 according to the arrow 41, by a distance d2 sufficient for the blade 20 of the knife 14 to cut the threshold 11 of the injection core 8. Another embodiment of the cutting tool 13 has been shown schematically in FIGS. 11 to 1: 3. This time it is a rotary cut variant, in which the knife 14 is pivotally movable around one of its ends 44. In this variant, the knife 14 has a fixed end in translation 44 and one end. 45. In the example shown, the fixed end 44 is pivotally mounted on a fixed arm 46. It could also be fixed on the punch 27 directly, on the injection shoe 34 or on any other intermediate fixed part, as long as this attachment allows the pivoting of the knife 14 around this point of attachment and does not interfere with the injection operation.

  The movable end 45 of the knife 14 is fixed on a guide arm 47 movable in translation, which preferably comprises, as before, a longitudinal guide extension 26, preferably a dovetail and intended to slide in a groove of the punch 27, and preferably an inclined bore 29 opening on the upper face 31 of the guide arm 47 by a substantially circular opening 30 so as to serve as actuating means.

  To allow the length adjustments necessary for the proper functioning of the cutting tool 13, the carrier strip 16 has at the mobile end of the knife 14 an elongate orifice 48, for example elliptical or rectangular, in which the fixing means 19 can slide while ensuring the assembly of the knife 14 to the guide arm 47. In the molding position shown in Figure 11, the knife 14 is as in the previous variants substantially perpendicular to the guide arms 46 and 47. The threshold 11 injection core 8 is molded near the cutting edge 23 of the blade 20 of the knife and has been shown in the form of a black band in the various figures.

  At the time of demolding and synchronized with the movement of the punch 27, there is a longitudinal displacement towards the front of the movable guide arm 47, symbolized by the arrow 49. This displacement can be directly caused by the movement of the punch 27 by means of an inclined finger 32 cooperating with an inclined bore 29 of the movable guide arm 47 according to the principle described above, or by any other means of actuation. This advance of the movable guide arm 47 drives in translation the moving end 45 of the knife 14 and consequently causes the knife 14 to pivot about the point of attachment of its fixed end 44. During this pivoting movement symbolized in the figures by the arrow 50, the blade 20 cuts through its cutting edge 23 the threshold 11 of the injection core 8. This cut is effected by a rotational movement, which advantageously reduces the forces to be provided with respect to a cut. FIG. 12 illustrates an intermediate position and FIG. 13 shows the limit position that can be reached with the device shown. In these figures, the movements have been exaggerated to better understand the operation of the device according to the invention. In operation, these can advantageously be much more limited, the threshold being already almost cut in the intermediate position of FIG. 12. These displacements, as well as the technical characteristics of the device and the actuating means enabling them to be realized, will be easily defined and optimized by those skilled in the art according to the characteristics of the threshold 11 to be sectioned. In Figures 14 to 18, there is shown another embodiment of the cutting device according to the invention which comprises a knife 51 movable in rotation in a substantially vertical plane. This embodiment makes it possible to produce a substantially vertical cut of the injection core 8. Unlike the previous embodiments, this device is suitable for cutting a threshold 11 of injection core 8 extending substantially horizontally, as is for example the case of the rod shown in Figure 1. The injection mold 28 and mainly the injection shoe 34 must be adapted accordingly. 15

  According to this variant, the device comprises a shutter element 52 which is preferably generally U-shaped with a base block 53 extended at each of its ends by a guide arm 54.

  As before, these guide arms 54 may advantageously comprise a longitudinally extending guiding section of substantially dovetail shape. This shutter element 52 makes it possible to close access to a housing 55 situated under the shutter element 52 and extending between the injection shoe 34 and the punch portion 27 of the mold 28. shutter 52 is movable between a closed position of the housing 55, shown in Figures 14 and 15, which it occupies during the molding operations and an opening position of the housing 55 allowing the cutting of the injection core 8 , shown in Figure 17. The passage from one to the other of these positions is effected by a translational movement of the sealing member 52, preferably caused by the action in cooperation of inclined fingers not shown and inclined bores adapted according to the principle widely described above.

  For this, each of the guide arms 54 of the closure member 52 preferably comprises an inclined bore 56 opening on the upper face by a substantially circular orifice 57. As can be seen in FIG. 14, these bores 56 are inclined in opposite directions with respect to the inclined bores 29 of the preceding embodiments, thus leading to a displacement of the sealing element 52 in the opposite direction to that of the cutting tool 13 of the previous variants. In the molding position shown in FIGS. 14 and 1.5, the element

  shutter 52 is in abutment against the injection shoe 34, thereby closing

  access to the housing 55. The upper face 58 of the closure member 52 extends the molding surface of the punch 27 and participates in the molding of the edge of the rod 2 and the threshold 11 of the injection core 8. The rotary knife 51 is then in the retracted position inside the housing 55. A: Kings molding and cooling completed, the punch 27 begins to deviate.

  Preferably, inclined fingers (not shown), secured to the matrix 33 and occupying at their other end the inclined bores 56, cause in a manner synchronized with the movement of the punch 27, a retreat of the closure member 52 towards the inside the mold in the direction of the removable element 38 of the punch. This movement of the shutter member 52 releases an access 59 to the housing 55 to allow cutting as illustrated in FIG. 17.

  After pivoting, the rotary knife 51 passes through the access 59 and protrudes outside the housing 55. By continuing its pivoting movement, it comes into contact with the threshold 11 and carries out its sectioning. Of course, the displacements of the closure element 52 can be controlled by any other appropriate means imaginable by those skilled in the art, in synchronism with the movement of the punch 27 and the pivoting of the rotary knife 51. The housing 55 encloses the rotary knife 51 and its actuating means, namely in this case a rotation mechanism 60. The knife 51 preferably comprises a blade 61 of generally triangular general shape. It can thus have two cutting edges 62 contiguous at its top and each extended by a bevelled edge 63. Advantageously, the actuating means of the knife 51 may comprise a pinion and rack device. According to the preferred variant shown, the blade 61 is mounted on a support piece 64. It is preferably assembled to the upper part of this piece 64 at a shoulder 65 thereof and a support plane 66 against which the blade 61 is put in place. The blade 61 is fixed by any appropriate means, such as for example screws 67, and preferably at oblong slots 68 which advantageously allow adjustment of the cutting radius of the knife 51. Preferably, the support piece 64 also comprises two symmetrical lateral extensions 69. On each of these lateral extensions 69 is fitted a ball bearing 70 so as to make a link to overcome between the support piece 64 and the punch 27 on one side and the support piece 64 and the shoe d injection 34 on the other side. The lateral extensions 69 thus serve as an axis of rotation for the pivoting of the support piece. 64 and thereby the knife 51. The lower part of the support piece 64 is preferably rounded and provided with an alternation of teeth 71 and recesses 72, for example of substantially trapezoidal section, in the manner of a wheel toothed. The support piece 64 thus plays the role of a pinion cooperating with a rack 73 which is disposed on the bottom of the housing 55 and which comprises on the upper face a series of teeth 74 and recesses 75 of complementary shape to those 71 and 72 The entire rotation mechanism 60 is moved by any suitable means, in a manner synchronized with the movement of the punch 27 and the movement of the punch 27.

  of the shutter element 52. According to a preferred variant shown in FIGS. 16 and 18, this setting in motion can be caused by the action of an inclined finger 76 secured to the matrix 33 and engaged in an inclined bore 77 73. In such a case, the displacement of the punch 27 causes a similar displacement of the bore 77 along the arrow 78, which under the effect of the inclined finger 76 drives the rack 73 in translation along the arrow 79 The teeth 74 and the recesses 75 of the rack 73 are respectively engaged with the recesses 72 and the teeth 71 of the pinion formed in the lower part of the support piece 64, the displacement of the rack 73 causes a pivoting of the support piece 64 according to the arrow 80. This pivoting results in a recovery of the knife 51 whose blade comes through the access 59 previously cleared by the sealing member 52, then by a sectioning of the threshold 11 the injection core 8 in the pursuit of the rotary movement of the knife 51. Obviously, the invention is not limited to the preferred embodiments described above and shown in the various figures, the skilled person can make it many modifications and imagine other variants without departing from the scope or scope of the invention.

  For example, if the injection mold 28 has several injection zones, the devices described above can be repeated at each of them. By thus multiplying the cutting points, it is advantageous to reduce the forces to be supplied locally for each cutting operation.

Claims (11)

  1. Device for cutting an injection core (8) connected by a threshold (11) to a plastic part (1), in particular a rod (2) for protection or embellishment of a vehicle body, molded by injection by means of a mold (28) comprising a punch (27) and a matrix (33), a cutting device characterized in that it is located in the injection mold (28) and in that comprises a movable knife (14, 51) disposed near the injection zone, which in the molding position does not interfere with the injection operation, and an actuating means (29, 32, 60) of the movable knife (14, 51) which causes movement of the movable knife leading to severing the threshold (11) of the injection core (8) synchronously with the movement of the punch (27) during demolding.   2. Cutting device according to the preceding claim characterized in that the actuating means (29, 32, 60) of the movable knife (14, 51) automatically comes into operation by the movement of the punch (27), simultaneously or with a certain delay in relation to this displacement.   3. Cutting device according to any one of the preceding claims characterized in that the actuating means (29, 32, 60) of the movable knife (14, 51) comprises at least one inclined finger (32, 76) cooperating with an inclined bore (29, 77).   4. Cutting device according to claims 2 and 3 characterized in that the inclined finger (32, 76) is part or is secured to the matrix (33) and has a slightly smaller diameter but substantially equal to the diameter of the inclined bore (29, 77) corresponding.   5. A cutting device according to claims 2 and 3 characterized in that the inclined finger (32, 76) is part or is secured to the matrix (33) and has a diameter smaller than the diameter of the inclined bore (29, 77). ) corresponding.   6. Cutting device according to any one of the preceding claims characterized in that: The knife (14) is movable in translation.   7. Cutting device according to the preceding claim characterized in that the movable knife (14) is fixed at each of its ends (17) on a guide arm (15).   8. Cutting device according to any one of claims 1 to 5 characterized in that the knife (14) is pivotally movable about one of its ends (44).   9. Cutting device according to the preceding claim characterized in that the other end (45) of the movable knife (14) is fixed on a guide arm (47) movable in translation.   10. Cutting device according to any one of claims 1 to 5 characterized in that the knife (51) is rotatable in a substantially vertical plane.   11. Cutting device according to the preceding claim characterized in that the knife (51) comprises a substantially triangular blade (61). L2. Cutting device according to claim 10 or 11 characterized in that the knife (51) is in the retracted position inside a housing (55) during the molding operations and projects outside this housing (55) to make the cut. 13. Cutting device according to any one of claims 10 to 12 characterized in that the actuating means (60) of the knife (51) comprises a pinion device (64) and rack (73). 14. Cutting device according to claims 12 and 13 characterized in that the knife (51) is mounted on a support member (64) whose rounded lower portion is provided with an alternation of teeth (71) and recesses (72). ) engaged with the teeth (74) and recesses (75) of a rack (73) disposed at the bottom of the housing (55). 15. Cutting device according to claim 12 characterized in that it further comprises a closure member (52) movable between a closed position of the housing (55) during the molding operations and a housing opening position (55) allowing the cutting of the injection core (8). 16. Cutting device according to the preceding claim characterized in that the shutter element (52) is generally U-shaped and comprises a base block (53) extended at each of its ends by a guide arm (54). ). 17. Cutting device according to claim 7, 9 or 16 characterized in that the or the guide arm (s) (15, 47, 54) comprises (s) a longitudinal extension of guiding (26) section substantially shaped tail d dove. 18. Cutting device according to any one of claims 7, 9 or 16 characterized in that the or the guide arm (15, 47, 54) comprises (s) an inclined bore (29, 56) opening on the upper face. (31) through an opening (30, 57). 19. Injection mold (28) comprising a punch (27) and a die (33), for use in the injection molding of a plastic part (1), in particular a protective strip (2) or embellishment of vehicle body, characterized in that it is equipped with at least one cutting device of an injection core (8) according to any one of the preceding claims. CERTIFIED CONF THE MANA "JJRE CEINET METZ PAT