DE102005018064A1 - Plastic component with metal insert and method for its production - Google Patents

Abstract

It is described a method for producing a plastic component with a metal insert used fluid-tight. For this purpose, a plastic body 1 is provided with a stepped bore 19, which has a holding portion 13, 15 and a sealing portion 11. Further, a metal insert 3 is provided, which has at its head end a sealing projection 31 and next to a retaining flange 33, 35. After introducing an annular sealant 5 in the bore 19 of the metal insert 3 is inserted into the bore 19, wherein the retaining flange 33, 35 is introduced with local softening of the plastic body 1 in the bore 19 until the sealing projection 31 is immersed in the annular sealant 5 , The plastic component produced in this way has the plastic body 1 and the metal insert 3 with the sealing projection 31. The outer diameter of the metal insert 3 on the side of the sealing projection 31 facing the plastic body 1 is always smaller than the diameter of the sealing projection 31.

Description

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

plastics have great importance in technology attained and can be adapted to a variety of requirements. Frequently it also requires combining plastic and metal, to take advantage of plastics with those of a component Metals (strength, wear resistance, electrical and thermal conductivity etc.).

Appropriate Metal inserts which are embedded in plastics are known. There are on the one hand the possibility, Insert the metal parts in a mold, in which then the plastic part On the other hand, there are proposals, a heated metal insert later under local Melting of the plastic body to use in these. The invention relates to the latter Solution.

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

According to this The prior art is provided, a metal insert on his in insertion direction seen front end (head end) to be provided with a groove in the an oring is used. Then the metal insert is heated and the heated metal insert is stepped into a graduated undersize Hole in the plastic body pressed. It melts the plastic limiting the bore, and hardens after inserting the metal insert again, so here is a intimate connection between metal and plastic is achieved. Of the Metal insert has a rough textured surface with grooves or teeth, so that the metal insert and the plastic body form-fitting with each other are connected.

In the method described in the above prior art is the O-ring attached to the metal insert and is pressed in to the inside of the body of the portion of the bore to be melted, acting as a sealing portion Advanced section of the stepped bore. By this procedure prevents the plastic-side sealing surface during Assembly touched and unintentionally deformed.

For the out known prior art method or plastic component thermally very stable O-rings made of expensive materials are used, since these are during the entire heating, the press-fitting process and the subsequent cooling of the Metal insert for exposed to the melting of the plastic required temperature are. In addition, there are damages at the O-ring and thus to fear leaks due to shearing of the O-rings are formed at the throat in the bore to form the sealing surface can. this could for example, by thermal expansion be caused on the heated O-ring, because the hot O-ring and thus significantly enlarged O-ring in the cold plastic case is pressed. Size Dimensional tolerances, the such a damage can safely avoid to missing pressure on the cold O-ring and thus also to leaks lead to the seal.

Further requires the installation of the O-ring in the metal insert Groove basically an expansion of the O-ring, which potentially means damage to the O-ring. moreover it can also come to the assembly to twist the O-ring, which also damages it to lead can.

In contrast, is It is an object of the invention to provide a plastic component with a fluid-tight used metal insert and a method for its production to propose, in and with the easy-to-install sealant can be used from simple materials and high reliability the seal between plastic body and metal insert ensured is.

These Task is with respect to the method with a method after Claim 1 and with respect to the plastic component with a plastic component solved according to claim 9.

in the inventive method for the manufacture of a plastic component is in a previously provided Plastic body with one to the outside of the plastic body open, stepped bore, the at least one to the outside of the Plastic body open holding portion and a body inside of the holding portion trained sealing section has inserted a metal insert. The provided metal insert has in the region of its inserted into the plastic body head end a sealing projection and at least one on the head end opposite side of the sealing projection formed retaining flange.

Before the metal insert is inserted into the plastic body, according to the invention an annular sealing means in the sealing portion of Hole - so 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 a thermoplastic and the metal insert is used the insertion heated. 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 process be carried out very quickly can. Alternatively, the metal insert with an ultrasonic generator be connected and put into high-frequency vibrations, around the plastic during insertion to soften by internal friction.

In An advantageous embodiment of the invention is the sealant an O-ring, before insertion is inserted into the sealing portion of the bore. Is appropriate it if the O-ring is sized so that it is lightly against the seal section is biased when it is inserted in the plastic body and so in the pre-assembled position is maintained. This will handle pre-assembled plastic body easier. If the O-ring is in place immediately before inserting the metal insert into the plastic body is inserted, wherein the bore is held upright in the plastic body can the O-ring should also be loosely inserted. In both cases mentioned causes only the immersion of the sealing projection of the metal insert the for the Sealing required contact forces on the O-ring.

A Alternative is that instead of an O-ring, the sealant a pasty one Applicable, bonding sealant is that prior to insertion of the Metal insert ring-shaped is applied to the sealing portion. This sealant can one gradually crosslinking in the crosslinked state elastic plastic (e.g. Silicone rubber); But alternatives can also be resin / hardener mixtures, such as e.g. Be multi-component adhesive, or elastic thermoplastics.

In an advantageous embodiment One is at the metal insert between the retaining flange and the Seal projection formed retaining shoulder when inserted into Opposing brought with the sealant. This retaining shoulder supports this respective sealant, this may also be one of the aforementioned alternatives Be sealant against the front of the metal insert acting on the O-ring pressure of the fluid to be sealed off. The Retaining shoulder function can also be taken over by the retaining flange be formed, which is adjacent to the sealing projection is. By doing so leaves the axial length shorten the metal insert.

In an advantageous embodiment of the invention has the metal insert two over an annular groove separate retaining flanges. The when inserting the Metal insert in the plastic body softened and displaced plastic flows in this groove and is there again. This is reflected the hardening of the Plastic a ring-shaped Tab that flows into the ring groove and fills it. In order to the hold of the metal insert is improved in the axial direction.

Finally is It is also advantageous if the retaining flange on its outer circumference with a surface structure is configured, the radial projections and intermediate Has indentations when inserting be filled by the softened plastic. This will be Metal insert and plastic body form-fitting connected and the hold of the metal insert in the plastic can continue be improved. In an advantageous embodiment, the Shape of the surface structure the expected forces be adjusted accordingly; for example, a toothing especially with teeth extending in the axial direction of the metal insert suitable if high torques at the connection metal / plastic may occur or transferred Need to become. The retaining flanges can also different surface shape to have.

As already executed The invention also relates to a plastic component with a Metal insert. According to the invention has a Plastic body one to the outside of the plastic body open, stepped bore, the at least one to the outside of the plastic body open holding portion and a body inside of the holding portion has trained sealing section.

One Metal insert, which is located in the area of his in the plastic body Heading a seal tab and at least one on top of that Head end opposite side of the sealing projection formed Holding flange has been added to the holding section of the bore and with the plastic body fusion bonded, wherein an annular sealant in the sealing portion the bore is arranged, the sealing projection of the metal insert in the annular Sealant immersed with the inner circumference of the sealant in pressender Attachment is and the sealant against the the sealing section radially outward biases. 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 at least one retaining flange a knurling with obliquely to the axial direction extending, intersecting grooves. Such a knurling is easy to make and allows high holding forces and the connection metal / plastic in both the axial direction as well as in the circumferential direction.

A particularly high torsional strength of the compound can be achieved when the Diameter of the at least one retaining flange is selected to be as large as possible while the axial forces the connection (acting on the head of the metal insert Fluid pressure forces) Remove with decreasing diameter of the seal protrusion. A diameter ratio of Holding flange diameter to seal protrusion diameter of about two to one is a workable value.

Further advantageous embodiments are described in the subclaims or emerge from the above statements on the method according to the invention corresponding.

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

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

2 a state in the proceeding method in the embodiment according to 1 ;

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

In 1 is a section of a plastic body 1 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 hole 17 , which carries the fluid to be sealed (here oil). In the plastic body 1 is a stepped bore 19 formed, the two holding sections 13 . 15 with different diameter, a sealing section 11 and a transition section 21 has that to the hole 17 is open. As in 1 The diameter of the stepped bore is clearly visible 19 from right to left in 1 from, ie the stepped bore 19 becomes the internal body of the plastic body 1 close.

In the 1 shown stepped bore 19 consists of a series of successive circular cylindrical sections with different diameters (smaller from left to right). In particular, the holding sections 13 . 15 However, they can also be frustoconical.

1 continues to show an O-ring 5 , The O-ring shown 5 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 a predetermined period of time, which is above the melting temperature of the plastic material from the plastic body 1 is shaped.

Further shows 1 a metal insert 3 , the two retaining flanges 33 . 35 with different diameters, a retaining shoulder 39 and a sealing projection 31 has, the front side a chamfer 41 having. The metal insert 3 is from an axial bore 43 interspersed, whose function does not need to be explained here. In the final assembled state are the hole 17 in the plastic body 1 and the axial bore 43 in metal insert 3 connected with each other. Between the two retaining flanges 33 and 35 is an annular groove 37 formed, which separates the two retaining flanges with mutually different diameters. The function of the annular groove 37 will be explained later.

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

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

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

As in 1 to 3 shown is the metal insert 3 a chamfer 41 at the head end, the end face of the metal insert and the sealing projection 31 connects with each other. The insertion of the metal insert 3 in the O-ring 5 gets through the chamfer 41 relieved and damage the O-ring 5 will be 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 sized so that the chamfer 41 after inserting the metal insert, not from the restoring forces of the compressed O-ring 5 is charged. This can avoid that the metal insert is loaded in the axial direction, such a burden must certainly be avoided as long as the plastic is still soft. Accordingly, the retaining shoulder is located 39 in the assembled state at a small distance from the O-ring 5 , as in 3 can be seen. When the plastic component is ready, ie after the plastic has become solid again, can and should the retaining shoulder 39 however with the O-ring 5 come into contact when it is migrated by high fluid pressures to be sealed in the direction of the pressure gradient or deformed.

In 3 is further shown that the annular groove 37 between the two retaining flanges 33 and 35 filled with plastic, which during melting during the joining process in this annular groove 37 occurred. In the cooled state thus extending in the circumferential direction of the metal insert plastic rib is formed, which with the metal insert 3 is positively locked and strengthened 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 that allows a positive connection with the plastic. This may in particular be knurling, toothing, longitudinal and / or transverse grooves or 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 (16)

Method for producing a plastic component with a metal insert used in a fluid-tight manner, comprising the steps of: providing a plastic body ( 1 ) with a to the outside of the plastic body ( 1 ) open, stepped bore ( 19 ), which has at least one holding section open to the outside of the plastic body ( 13 . 15 ) and a body inside of the holding portion formed sealing portion ( 11 ), providing a metal insert ( 3 ), which is in the area of its in the plastic body ( 1 ) to be introduced head end a sealing projection ( 31 ) and at least one on the side facing away from the head end of the sealing projection ( 31 ) formed retaining flange ( 33 . 35 ), introducing an annular sealant ( 5 ) in the sealing section ( 11 ) of the bore ( 19 ), and then inserting the metal insert ( 3 ) into the hole ( 19 ), wherein the at least one retaining flange ( 33 . 35 ) with local softening of the plastic body ( 1 ) in the holding section ( 13 . 15 ) of the bore ( 19 ) is inserted until the sealing projection ( 31 ) of the metal insert ( 3 ) in the annular sealant ( 5 immersed). Method according to claim 1, characterized in that the plastic body ( 1 ) consists of a thermoplastic material and the metal insert ( 3 ) is heated before insertion. Method according to claim 1, characterized in that that the metal insert is connected to an ultrasonic generator and vibrated to soften the plastic during insertion. Method according to claim 1, 2 or 3, characterized in that the sealing means comprise an O-ring ( 5 ) which, prior to insertion into the sealing section ( 11 ) of the bore ( 19 ) is inserted. A method according to claim 1, 2 or 3, characterized in that the sealing means is a pasty orderable, setting sealant which prior to insertion of the metal insert ( 3 ) annularly on the sealing portion ( 11 ) is applied. Method according to one of the preceding claims, characterized in that the metal insert ( 3 ) one to the sealing projection ( 31 ) adjacent retaining shoulder ( 39 ), which when inserted in opposition to the sealant ( 5 ) is brought. Method according to one of the preceding claims, characterized in that the metal insert ( 3 ) two via an annular groove ( 37 ) separate retaining flanges ( 33 . 35 ), wherein the plastic softened upon insertion into the annular groove ( 37 ) flows and fills them. Method according to one of the preceding claims, characterized in that the at least one retaining flange ( 33 . 35 ) is formed on its outer peripheral surface with a surface structure having radial projections and recesses therebetween, which are filled in the insertion of the softened plastic. Plastic component with a metal insert, with a plastic body ( 1 ) with an open to the outside of the plastic body, stepped bore ( 19 ), which at least one to the outside of the plastic body ( 1 ) open holding section ( 13 . 15 ) and a body inside of the holding section ( 13 . 15 ) formed sealing section ( 11 ), a metal insert ( 3 ), which is in the area of its in the plastic body ( 1 ) a sealing projection ( 31 ) and at least one on the side facing away from the head end of the sealing projection ( 31 ) formed retaining flange ( 33 . 35 ), which in the holding section ( 13 . 15 ) of the bore ( 19 ) and with the plastic body ( 1 ) is melt-bonded, and an annular sealant ( 5 ) in the sealing section ( 11 ) of the bore ( 19 ), wherein the sealing projection ( 31 ) of the metal insert ( 3 ) in the annular sealant ( 5 ), with the inner periphery of the sealant ( 5 ) is in pressing system and the sealant ( 5 ) against the sealing portion ( 11 radially outwardly biased, 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 ). Plastic component according to claim 9, characterized in that the sealing means is an O-ring ( 5 ). Plastic component according to claim 9, characterized in that the sealing means has a clearance between the sealing projection ( 31 ) and the sealing portion ( 11 ) is filling, hardened sealing paste. Plastic component according to claim 9, 10 or 11, characterized in that the metal insert ( 3 ) one to the sealing projection ( 31 ) adjacent retaining shoulder ( 39 ) at which the sealant ( 5 ) is present. Plastic component according to one or more of claims 9 to 12, characterized in that the metal insert ( 5 ) two via an annular groove ( 37 ) separate retaining flanges ( 33 . 35 ), which integrally with the plastic body ( 1 ) trained ring section receives. Plastic component according to one or more of claims 9 to 13, characterized in that the at least one retaining flange ( 33 . 35 ) is formed on its outer peripheral surface with a surface structure having radial projections and recesses therebetween, which are filled with plastic. Plastic component according to claim 14, characterized in that that the surface texture a knurling and / or axially extending ribs and / or circumferential grooves. 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 ).