WO2006111221A1

WO2006111221A1 - Plastic component comprising a metal insert and method for the production thereof

Info

Publication number: WO2006111221A1
Application number: PCT/EP2006/002180
Authority: WO
Inventors: Jürgen Jester; Stefan Fischer
Original assignee: Honeywell Gmbh
Priority date: 2005-04-19
Filing date: 2006-03-09
Publication date: 2006-10-26
Also published as: DE102005018064A1

Abstract

The invention relates to a method for producing a plastic component comprising a metal insert which is introduced in a fluid-tight manner. A plastic body (1) having a stepped bore (19), which comprises a maintaining section (13, 15) and a sealing section (11), is provided. The invention also relates to a metal insert (3) which comprises a sealing projection (31) and also a maintaining flange (33, 35) on the head end thereof. The metal insert (3) is introduced into the bore (19) after the tubular shaped sealing agent (5) has been introduced into said bore (19). The maintaining flange (33, 35) is inserted into the bore (19) until the sealing projection (31) dips into the annular-shaped sealing element (5) when the plastic body (1) is locally softened. The thus produced plastic component comprises a plastic body (1) and a metal insert (3) which is provided with a sealing projection (31). The external diameter of the metal insert (3) on the side of the sealing projection (31) which is oriented towards the plastic body (1) is smaller that the diameter of the sealing projection (31).

Description

description

Plastic component with metal insert and method for its

manufacturing

The invention relates to a method for producing a plastic component with a metal insert and such a plastic component.

Plastics have become very important in the art and can be adapted to a variety of requirements. Often it is also necessary to combine plastic and metal together to unite on a component, the advantages of plastics with those of metals (strength, wear resistance, electrical and thermal conductivity, etc.).

Corresponding metal inserts which are embedded in plastics are known. On the one hand, there is the possibility of inserting the metal parts into a mold in which the plastic part is then produced; on the other hand, there are proposals to use a heated metal insert subsequently with local melting of the plastic body in these. The invention relates to the latter solution.

Such a solution is known for example from EP-A-0551717. In this document, a plastic component with a metal insert and a method for its production is described, wherein the metal insert by means of an O-ring seal against the plastic part is sealed.

According to this prior art, it is provided to provide a metal insert at its front end (head end) seen in the insertion direction with a groove into which an O-ring is inserted. Then the metal insert is heated and the heated metal insert is pressed into a stepped bore of appropriate size in the plastic body. In this case, the plastic bounding the bore melts, and hardens again after insertion of the metal insert, so that an intimate bond between metal and plastic is achieved here. The metal insert has a rough textured surface with grooves or teeth, so that the

Metal insert and the plastic body are positively connected with each other.

In the method described in the above prior art, the O-ring is attached to the metal insert and is advanced during injection to the portion of the stepped bore located inside the meltable bore portion, which acts as a seal portion. This procedure prevents the plastic-side sealing surface from being touched and unintentionally deformed during assembly.

For the well-known from the prior art method or plastic component thermally very stable O-rings made of expensive materials are used because they are exposed throughout the heating, the press-fitting process and the subsequent cooling of the metal insert required for the melting of the plastic temperature. In addition, damage to the O-ring and thus leaks are to be feared by shearing of the O-ring may be formed at the constriction in the bore to form the sealing surface. This could be caused for example by thermal expansion of the heated O-ring, since the hot O-ring and thus significantly enlarged O-ring is pressed into the cold plastic housing. Large dimensional tolerances that reliably avoid such damage can lead to a lack of pressure on the cold O-ring and thus also to leaks in the seal.

Furthermore, the mounting of the O-ring in the groove provided for this purpose in the metal insert generally requires widening of the O-ring, which potentially means damage to the O-ring. In addition, it can also come to the assembly to twist the O-ring, which can also lead to damage.

In contrast, it is an object of the invention to provide a plastic component with a metal insert used fluid-tight and a method for its production, in and with an easy to install

Dichtraittel can be used from simple materials and a high reliability of the seal between plastic body and metal insert is ensured.

This object is achieved with regard to the method with a method according to claim 1 and with regard to the plastic component with a plastic component according to claim 9.

In the inventive method for producing a

Plastic component is in a previously provided plastic body with an open to the outside of the plastic body, stepped bore, the at least one open to the outside of the plastic body holding portion and a body inside of the Holding portion formed sealing portion has used a metal insert. The provided metal insert has a sealing projection in the region of its head end to be introduced into the plastic body and at least one retaining flange formed on the side of the sealing projection which faces away from the head end.

Before the metal insert is inserted into the plastic body, according to the invention an annular sealing means in the sealing portion of the bore - ie in the

Plastic body - used. Only then is the metal insert introduced into the bore, with the at least one retaining flange being introduced into the retaining portion of the bore with local softening of the plastic body until the sealing projection of the metal insert dips into the annular sealant.

Preferably, the plastic body is made of a thermoplastic and the metal insert is heated prior to insertion. The temperature of the metal insert is preferably chosen so high that instantaneous melting of the plastic body occurs at the edge of the hole, so that the actual insertion can be performed very quickly. Alternatively, the metal insert with a

Ultrasonic generators be connected and are placed in high-frequency vibrations to soften the plastic during insertion by internal friction.

In an advantageous embodiment of the invention, the sealing means is an O-ring, which is inserted before insertion into the sealing portion of the bore. It is useful if the O-ring is dimensioned so that it is slightly biased against the sealing portion when it is inserted into the plastic body and so in the pre-assembled position is maintained. This makes the handling of pre-assembled plastic body easier. If the O-ring is inserted into the plastic body immediately before inserting the metal insert, with the hole kept upright in the plastic body, the O-ring may also be loosely inserted. In both of the aforementioned cases, only the immersion of the sealing projection of the metal insert causes the contact forces required for the sealing on the O-ring.

An alternative is that instead of an O-ring, the sealant is a pasty coatable, setting sealant which is applied annularly to the seal portion prior to insertion of the metal insert. This sealant can be a gradually cross-linking in cross-linked! Condition of elastic plastic (e.g., silicone rubber); However, alternatives can also be used for resin / hardener mixtures, such as Be multi-component adhesive, or elastic thermoplastics.

In an advantageous embodiment, a retaining shoulder formed on the metal insert between the retaining flange and the sealing projection is brought into contact with the sealing means when inserted. This retaining shoulder supports the respective sealing means, which may also be one of the aforementioned alternative sealing means, against the pressure of the fluid to be sealed from the end face of the metal insert acting on the O-ring. The retaining shoulder function can also be taken over by the retaining flange, which is adjacent to the

Seal protrusion is formed. As a result, the axial length of the metal insert can be shortened.

In an advantageous embodiment of the invention, the metal insert has two separate via an annular groove Retaining flanges. The softened and displaced during insertion of the metal insert in the plastic body plastic flows into this groove and is there again. This forms after hardening of the plastic, an annular projection which flows into the annular groove and fills it. This improves the hold of the metal insert in the axial direction.

Finally, it is also advantageous if the retaining flange is designed on its outer circumference with a surface structure having radial projections and recesses therebetween, which are filled during insertion of the softened plastic. As a result, metal insert and plastic body are positively connected and the maintenance of the metal insert in the plastic can be further improved. In an advantageous embodiment, the shape of the surface structure can be adapted to the expected forces accordingly; For example, a toothing with extending in the axial direction of the metal insert teeth is particularly suitable when high torques can occur at the compound metal / plastic or must be transmitted. The retaining flanges can also have different surface shape.

As already stated, the invention also relates to a plastic component with a metal insert. According to the invention, a plastic body has a stepped bore which is open towards the outside of the plastic body and has at least one to the outside of the

Plastic body has open holding portion and a body inside of the holding portion formed sealing portion. A metal insert, which has a sealing projection and at least one on the side facing away from the top end of the sealing projection formed retaining flange in the region of its located in the plastic body head end is received in the holding portion of the bore and with the plastic body fusion-bonded, wherein an annular sealing means disposed in the sealing portion of the bore is, the sealing projection of the metal insert is immersed in the annular sealant with the inner periphery of the sealant in abutting contact and biases the sealant against the sealing portion radially outwardly. The outer diameter of the metal insert on the plastic body side facing the sealing projection is always smaller than the diameter of the sealing projection.

In an advantageous embodiment, the surface structure of the peripheral surface of the at least one retaining flange is a knurling at an angle to the

Axially extending, intersecting grooves. Such a knurling is easy to produce and allows high holding forces and the connection metal / plastic in both the axial direction and in the circumferential direction.

A particularly high torsional strength of the connection can be achieved if the diameter of the at least one retaining flange is selected to be as large as possible, while the axial forces acting on the connection (which on the head of the

Metal insert acting fluid pressure forces) decrease with decreasing diameter of the sealing projection. A diameter ratio of retaining flange diameter to seal protrusion diameter of about two to one is a practical value. Further advantageous embodiments are described in the dependent claims or arise from the above statements on the method according to the invention accordingly.

The invention will be explained in more detail below with reference to a preferred embodiment with reference to the drawing. It shows:

1 shows schematically an initial situation before the joining of metal insert and plastic body according to an embodiment of the invention;

FIG. 2 shows a state in the proceeding process in the embodiment according to FIG. 1; FIG.

Fig. 3 shows schematically the assembled connection of plastic body and metal insert.

In Fig. 1, a portion of a plastic body 1 is shown, which in the present embodiment belongs to an oil pressure sensor for an internal combustion engine of a motor vehicle. Other components and portions of the oil pressure sensor are not important to the explanation of the present invention and are omitted for the sake of brevity. The plastic body 1 has a bore 17 which carries the fluid to be sealed (here oil). In the plastic body 1, a stepped bore 19 is formed, which has two holding portions 13, 15 of different diameter, a sealing portion 11 and a transition portion 21 which is open to the bore 17. As can be clearly seen in Fig. 1, the diameter of the stepped bore 19 increases from right to left in Fig. 1 from, ie the stepped bore 19 is closer to the body interior of the plastic body 1.

The stepped bore 19 shown in Fig. 1 consists of a series of successive circular cylindrical

Sections with different (smaller from left to right) diameters. In particular, however, the holding portions 13, 15 may also be designed frustoconical.

Fig. 1 further shows an O-ring 5. The O-ring 5 shown has an annular ^' body 51 which is formed by a circular cross-section cord. The O-ring 5 is made of a material that can withstand a temperature for at least a predetermined period of time, which is above the melting temperature of the plastic material from which the plastic body 1 is formed.

Further, Fig. 1 shows a metal insert 3, the two

Holding flanges 33, 35 with different diameters, a retaining shoulder 39 and a sealing projection 31 has the end face a chamfer 41. The metal insert 3 is penetrated by an axial bore 43, the function of which does not need to be explained in detail here. In the final assembled state, the bore 17 in the plastic body 1 and the axial bore 43 in the metal insert 3 are interconnected. Between the two retaining flanges 33 and 35, an annular groove 37 is formed, which separates the two retaining flanges with different diameters from each other. The function of the annular groove 37 will be explained later.

2, an advanced state is shown in the method according to the embodiment. Here, the O-ring 5 is already inserted into the Kunstoffoffkörper 1 and in the Seal portion 11 of the stepped bore 19 is arranged. In the schematic illustration in FIG. 2, the O-ring 5 is slightly deformed (flattened) on its outer circumference. Thus, it is shown that the dimensions of O-ring 5 and seal portion 11 of the stepped bore 19 are tuned so that the O-ring 5 is slightly biased against the seal portion 11 due to its own elasticity and thus held in or near the mounting position, even if the plastic body 1 is still moved or transported after insertion of the O-ring 5.

Subsequently, the metal insert 3, which is heated to a suitable temperature, pressed according to arrow P in the plastic body 1. The vertical, upwardly open orientation of the stepped bore 19 of the plastic body 1 shown in the illustration of FIG. 2 corresponds to the actual procedure, and since the melting during insertion of the metal insert plastic material may be thin and run at a different orientation of the stepped bore 19 irregular can. The vertical position of the stepped bore 19 is a simple and effective measure that ensures a uniform distribution of the melting plastic on the circumference of the metal insert 3.

In the inserted state of the metal insert 3, the O-ring 5 is compressed between the seal projection 31 (arrow A in FIG. 2) and the seal portion 11 of the stepped bore 19 (arrow B in FIG. 2), as shown in FIG.

As shown in Figs. 1 to 3, the metal insert 3 has a bevel 41 at the head end, the end face of the metal insert and the sealing projection 31 together combines. The insertion of the metal insert 3 in the O-ring 5 is facilitated by the chamfer 41 and damage to the O-ring 5 is prevented. The chamfer 41 is not shown to scale in the figures, actually enough here a few tenths of a millimeter wide bevel. The length of the sealing projection 31 and the retaining shoulder 39 are dimensioned so that the chamfer 41 is not acted upon by the restoring forces of the compressed O-ring 5 after insertion of the metal insert. This can be avoided that the metal insert in

Axial direction is loaded, such a burden must certainly be avoided so long as long as the plastic is still soft. Accordingly, the retaining shoulder 39 is in the assembled state at a small distance from the O-ring 5, as can be seen in Fig. 3. When the plastic component is finished, i. However, after the plastic has become solid again, the retaining shoulder 39 can and should come into contact with the O-ring 5 when it moves or is deformed by high fluid pressures to be sealed in the direction of the pressure gradient.

In Fig. 3 is further shown that the annular groove 37 is filled between the two retaining flanges 33 and 35 with plastic, which has occurred during melting during the joining operation in this annular groove 37. In the cooled state, a plastic rib extending in the direction of insertion of the metal insert is thus formed, which is positively locked with the metal insert 3 and reinforces the connection in the axial direction.

In the figures, it is not further shown that the outer peripheral surfaces of the retaining flanges 33 and 35 are provided with a surface structure which allows a positive connection with the plastic. This can in particular a knurling, gearing, longitudinal and / or transverse grooves or be similar designs. A design with a toothing improves the strength against twisting of metal insert relative to the plastic body. The present metal insert provides a thread exclusion with the substantially plastic component. In this case, the torsional strength in addition to the holding force against the expected fluid pressures is of particular importance.

Claims

claims

1. A process for producing a plastic component with a metal insert used fluid-tight, with the

steps:

Providing a plastic body (1) with a to the outside of the plastic body (1) open, stepped

Bore (19), the at least one open to the outside of the plastic body holding portion (13, 15) and a body inside of the holding portion formed

Sealing section (11) has,

Providing a metal insert (3), which is used in

In the region of its head end to be introduced into the plastic body (1), a sealing projection (31) and at least one side of the head end facing away from the head end

Seal projection (31) formed retaining flange (33,

35),

Inserting an annular sealant (5) into the seal portion (11) of the bore (19), and then inserting the metal insert (3) into the bore (19), the at least one retaining flange

(33, 35) with local softening of the plastic body

(1) into the holding portion (13, 15) of the bore (19) is inserted until the sealing projection (31) of the

Metal insert (3) is immersed in the annular sealing means (5).

2. The method according to claim 1, characterized in that the plastic body (1) made of a thermoplastic

Plastic and the metal insert (3) is heated prior to insertion.

3. The method according to claim 1, characterized in that the metal insert is connected to an ultrasonic generator and is vibrated to soften the plastic during insertion.

4. The method of claim 1, 2 or 3, characterized in that the sealing means is an O-ring (5), which is inserted prior to insertion into the sealing portion (11) of the bore (19).

5. The method of claim 1, 2 or 3, characterized in that the sealing means is a pasty orderable, bonding sealant, which is applied before the insertion of the metal insert (3) annularly on the sealing portion (11).

6. The method according to any one of the preceding claims, characterized in that the metal insert (3) has a to the sealing projection (31) adjacent retaining shoulder (39), which is brought upon insertion in opposition to the sealing means (5).

7. The method according to any one of the preceding claims, characterized in that the metal insert (3) has two via an annular groove (37) separate retaining flanges (33, 35), wherein _. the plastic softened upon insertion flows into and fills the annular groove (37).

8. The method according to any one of the preceding claims, characterized in that the at least one retaining flange (33, 35) is configured on its outer peripheral surface with a surface structure having radial projections and recesses lying therebetween, the be filled during insertion of the softened plastic.

9. plastic component with a metal insert, with a Kunstoffoffkörper (1) with a for

Outside of the plastic body open, stepped bore (19) having at least one to the outside of the plastic body (1) open holding portion (13, 15). and a seal portion (11) formed on the inside of the holding portion (13, 15), a metal insert (3) having a sealing projection (31) and at least one side remote from the head end in the region of its head end located in the plastic body (1) Seal projection (31) formed retaining flange (33, 35), which in

Holding portion (13, 15) of the bore (19) is received and with the plastic body (1) is fusion bonded, and an annular sealing means (5) which is arranged in the sealing portion (11) of the bore (19), wherein the sealing projection (31) of the Metal insert (3) is immersed in the annular sealing means (5), is in pressing contact with the inner circumference of the sealing means (5) and biases the sealing means (5) radially outward against the sealing section (11), characterized in that the outer diameter of the metal insert ( 3) on the plastic body (1) facing side of the sealing projection (31) is always smaller than the diameter of the sealing projection (31).

10. plastic component according to claim 9, characterized in that the sealing means is an O-ring (5).

11. Plastic component according to claim 9, characterized in that the sealing means is a Gap is between the sealing projection (31) and the sealing portion (11) filling hardened sealing paste.

12. Plastic component according to claim 9, 10 or 11, characterized in that the metal insert (3) has a sealing projection (31) adjacent retaining shoulder (39) against which the sealing means (5).

13. Plastic component according to one or more of claims 9 to 12, characterized in that the metal insert (5) has two via an annular groove (37) separate retaining flanges (33, 35) which receives a one-piece with the plastic body (1) formed annular portion ,

14. Plastic component according to one or more of claims 9 to 13, characterized in that the at least one retaining flange (33, 35) is configured on its Äufßenumfangsfläche with a surface structure having radial projections and recesses lying therebetween, which are filled with plastic.

15. Plastic component according to claim 14, characterized in that the surface structure comprises a knurling and / or axially extending ribs and / or circumferential grooves.

16. Plastic component according to one or more of claims 9 to 15, characterized in that the

Diameter of the retaining flange (33, 35) is at least twice as large as the diameter of the sealing projection (31).