DE6924990U - CLOSED FORM AND MOLDED PART WITH ONE-PIECE BURN - Google Patents

Description

My mark: 673 pg 69.87

Applicant:

Saunders Valve Company Limited C wm "bra η / Great Britain

Title: Method of shaping objects in

a closed, multi-part shape, closed shape and molded part with one one-piece press burr

The present invention is concerned with the formation of articles in closed molds from which the molded Object '. Is removed from each other by separating the molded parts.

It is common practice in these molding processes to slightly overfill the mold cavity so that there are no bubbles or voids in the molded part Object or molded part are created; the excess material forms in the plane in which the molded parts are separated from each other a press burr which must be removed in order for the molded article to have a satisfactory exterior surface. at For certain materials, this flash removal can be difficult and time consuming, and if the removal of the If burring is not done carefully, the molded article may be damaged, rendering it unusable Reject occurs.

Phone: 38 02 3B. Telegram: Ir ill

Cologne 123 61 BI ■ Postecheck Cologne 152 2S1

The present invention is based on the object of overcoming this difficulty by designing the shape differently, so that a press flash is produced which is shaped to be easily removed from the molded article can be, with - if at all - there is hardly any risk of damage to the object.

To solve this problem, the invention provides a method for forming objects in a closed, from several, separable parts before existing form, in which the mold cavity is overfilled, so that the excess Forming material around the outer edge of the object forms a press burr, according to the invention to facilitate the subsequent elimination of the press burr is provided that the press burr at its connection point to the object as forms a relatively thin membrane and makes it thicker to the outside, away from the object.

The invention also relates to a closed shape, which consists of several, separable parts, of which at least two between each other opposite Faces form a mold cavity which has the shape of the object to be molded, it is provided according to the invention, that the opposing surfaces of the two mold parts also form a press flash cavity outside the mold cavity have, the depth of which increases from the outer boundary of the mold cavity away to the outside.

The invention also relates to a molded part with a one-piece Press burr that protrudes from the outer boundary of the molded part to the outside, which is provided according to the invention, that the press burr at its connection point to the molded part has the shape of a relatively thin membrane and after outside increases in thickness. The one-piece press burr can extend around the outside or the inside of the molded part, if this has such an inside, it can

j 692499018.3.71

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in the latter case, however, such a press burr is also used both around the outside and around the inside of the molded part extend.

The invention is and is particularly advantageously applicable to the formation of rubber O-rings with small tolerances now further described with reference to this application, however, it should be pointed out that the invention is also generally otherwise with the same or similar advantage is applicable.

/ The accompanying drawing shows a section through a two-part Form for forming rubber O-rings, this form is designed according to the invention and wherein the cutting plane of the accompanying drawing is at right angles to the parting plane between the two mold parts runs. The main mold cavity 1 for forming the O-ring is formed by two semicircular grooves in the upper and lower mold parts 2 and 3 formed; on both sides of this main mold cavity 1 a press burr cavity 4 is arranged, which is formed by grooves triangular in cross section in the mold parts 2 and 3, the distance between the Main mold cavity 1 and the press burr cavities 4 preferably within the allowable residual press burr tolerance of the molded Object and may be, for example, on the order of 0.0762 mm (three thousandths of an inch). The one another opposite surfaces of parts 2 and 3 of the mold are flat in this area and, if no press flash material is present they would touch each other.

At least on the outside of these three cavities 1, 4 is Another Hauptpreßgrathohlraum 5 is provided and, if the inner diameter of the O-ring allows, another is Hauptpreßgrathohlraum 6 on the inside of the cavities 1, 4, 4, is provided.

When using such a shape, the volume of all

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three cavities 1, 4 and 4 when determining the filling quantity is taken into account and a little more material is added than is necessary to fill this volume. Through this it is ensured that all three cavities are filled and at least some material is in the cavity 5 or cavities 5 and 6 reached. After the molding process and the separation of the parts of the mold from each other, the molded O-ring 2 is in position its inside and outside with very thin membranes of molded material attached to ribs. You can get these ribs easily remove by grasping each of these ribs and tearing the thin diaphragm so that the O-ring from the ground of the press flash material is separated, with any press flash material possibly remaining on the O-ring within the Tolerance range must be.

Depending on the volume of the material used for molding the press burr around the molded O-ring will have one or two additional ribs around the outer one connected to the ring Rib run around or within the inner rib connected to the ring, with the two ribs on each side of the O-ring are connected to each other by another thin membrane. Both ribs can be in one Tear-off process can be easily removed.

The press burr formed during the molding process does not have to be as described above, have rib-like shape, although this rib shape has been found to facilitate tearing; important is just that the thickness of the flash increases in the direction away from the O-ring. This ensures that the thinnest and consequently the most easily tearable part of the press flash is at the point where it connects to the O-ring.

So that the thin membrane connecting the thicker part of the press burr with the O-ring is as thin as is just possible, the two parts 2 and 3 of the mold should be pressed firmly against each other by pressing on one or

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both parts of the mold exerting pressure or by making the weight of the upper mold part so great that the planes, each other opposite faces of the parts of the mold almost come into contact with each other.

The invention has been illustrated in detail using the example of the formation of a O-ring described, but it is obvious that the Invention in the shaping of any other objects is equally applicable.

Claims (7)

Expectations 1. Closed form, made up of several, separable from each other Parts consists of which at least two ± "form a mold cavity between opposing surfaces, which the Shape of the object to be molded, characterized in that the opposite Surfaces of the two mold parts (2, 3) also outside of the mold cavity (1) have a Preßgratholraum (4), the depth of which increases away from the outer boundary of the mold cavity to the outside. 2. Closed mold according to claim 1 for molding objects with an outer and an inner boundary, characterized in that the opposite Areas of the two parts (2, 3) of the mold (1) also form a press burr cavity within the inner boundary of the mold cavity (1) (4) form whose depth inwards, from the inner Telephone: 38 O2 3Θ ■ Telegram tn (17 ! Cologne 1236181 Post check: Cologne iS22ai - 2 boundary of the molded part increases away. 3. Closed mold according to claim 1 or 2, characterized in that the opposite Surfaces of the parts (2, 3) of the mold (1) are flat directly on this boundary or these boundaries of the molded part. 4. Closed mold according to claim 3, characterized in that the opposing surfaces of the parts (2, 3) of the mold (1) are designed such that, if there is no press flash material, these surfaces are touch with their flat parts when the shape is put together. 5. Closed mold according to one of claims 1, 2, 3 or 4, characterized in that the press burr cavity (4) on the outside of the molded part as an auxiliary press burr cavity is formed directly on the outside of the molded part and that a Hauptpreßgrathohlraum (5) at a distance is arranged outside of this Hilfspreßgrathohlraumes. 6. Closed mold according to claim 2 or 3 to 5, characterized in that the press burr cavity (4) is formed on the inside of the molded part as an auxiliary press burr cavity directly on the inside of the molded part and that a main press burr cavity (6) spaced within this auxiliary press burr cavity on the inside of the mold ! part is trained. j 7. Closed mold according to claim 5 or 6, characterized in that the main and auxiliary press burr cavity (4, 5, 6) of complementary V-shaped grooves Cross-section in the opposing surfaces of the parts (2, 3) of the mold (1) are formed. 6. Molded part with a one-piece press burr, which protrudes from the j outer boundary of the standard part to the outside, thereby (marked that the Preßgrax at its connection point on the molded part has the shape of a relatively thin membrane and increases in thickness towards the outside. 9. Molding with a one-piece press burr which protrudes inward from the inner boundary of the molding, thereby characterized in that the PreSgrat at its connection point to the molded part, the shape of a relatively has a thin membrane that increases in thickness towards the inside. 10. Molding according to claims 8 or 9, characterized in that the one-piece PreßÄgrat the Has the shape of a rib which is connected to the molded part by a relatively thin membrane. 11. Molding according to claim 10, i characterized in that the one-piece press burr is a further Has rib which is connected to the first-mentioned rib by a relatively thin membrane. 12. Molding according to one of claims 8 to 10, characterized in that the molding is an O-ring.