DE102008038018A1 - Assembly for joining thermoplastic elements by welding, particularly contact-welding, has three welds of thermoplastic welded plastic elements - Google Patents

Abstract

The assembly has three welds of thermoplastic welded plastic elements, in which, an intermediate element is arranged as a third element between the former and the latter plastic elements. The intermediate element rests on the former plastic element and the latter plastic element faces the joining surface adjacent to another joining surface of the latter plastic element. An independent claim is included for a method for manufacturing an assembly.

Description

The The invention relates to an assembly with at least three welds welded together thermoplastic plastic parts, in which between a first and a second plastic part an intermediate part is arranged as a third plastic part.

To the Connecting thermoplastic parts by welding are several in particular non-contact welding methods known. In all of these methods, the plastic of the two together plastic parts to be joined in areas (joining surfaces) the plastic parts in which the parts are joined together should, melted, whereupon then the parts with their joining surfaces pressed against each other and thereby welded together become.

Known, applicable for this welding methods are friction welding, further methods in which the plastic is melted by an energy radiation (infrared welding, so-called mirror welding, and welding by means of ultrasound), but also the so-called hot gas welding, in which a hot gas, the opposite to the plastic melt is inert, directed from one or more nozzles on against the weld to be produced corresponding areas of the plastic parts to be welded together and thereby in these areas of the plastic is melted (see for example the DE-100 19 300-B4 and the EP-1 415 789-B1 ). For friction welding it should be noted that it is true that two thermoplastic plastic parts can be connected together in one step along a weld created by friction welding, but the quality of this weld produced by friction welding often does not meet all requirements, because finely divided abrasion occurs during friction welding, especially then when at least one of the plastic parts is fiber reinforced, and this abrasion not only affects the strength of the joint but also the often desired gas tightness of the weld.

The Production of an assembly of the type mentioned so far is done in two steps: First, the first Plastic part welded to the intermediate part, and in a second step, the first plastic part and the intermediate part with welded to the second plastic part.

Of the Invention was the object of an assembly of the above to develop defined type, which easier and therefore more cost-effective can be produced.

These Task can be inventively characterized solve that the assembly is designed so that the intermediate part rests on the first plastic part and with a second Plastic part facing first joining surface a second joining surface of the second plastic part adjoins one provided on the first plastic part and the second Plastic part facing third joining surface adjacent to a fourth joining surface of the second plastic part, and that the welds on the one hand in the first and second joining surface and on the other in the third and fourth joining surface.

In It should be noted that, the plastic parts were over the entire joining surfaces melted, the joining surfaces no longer recognizable as interfaces in the finished assembly are.

A inventive assembly can be produce very simply and cost-saving, because after the Placing the intermediate part on the first plastic part of the plastic in the area of the four joint surfaces by one for this suitable tool can be melted at the same time everywhere, where the welds lie in the finished assembly, whereupon the second plastic part against the intermediate part and the first plastic part is pressed that the first and the second Joining surface also be pressed against each other like the third and the fourth joining surface and thereby The welds are created by the first plastic part including intermediate part is connected to the second plastic part. Of course you could also do the first plastic part Press with applied intermediate part against the second plastic part, to create the welded joints.

As will be apparent from the following description, can be in this way also welds in the form of welds as it does with any of the above-mentioned welding methods possible is the plastic in elongated areas the four joining surfaces everywhere at the same time melt.

In preferred embodiments of the assembly according to the invention are (in a plan view of the assembly), the third and fourth joining surface adjacent to an edge of the intermediate part, so that the third and fourth joining surface have only a small distance from the edge of the intermediate part. This results in a particularly stable connection of the three plastic parts together. The edge of the intermediate part can be an outer edge, but also an edge located in the interior of the intermediate part. In particularly advantageous embodiments of the assembly according to the invention, however, the first joining surface lies in an outer edge region of the intermediate part (in a top view of the assembly); In such a case, the first and / or the second plastic part can be made almost arbitrary in terms of their third and fourth joining surface forming areas. In addition, such a module according to the invention has yet another advantage: forming the first and the second plastic part and / or one of these two plastic parts together with the intermediate part one or more cavities, which must or must be sealed liquid and / or gas tight , it may be sufficient if only one lying in the first and second joining surface weld or a lying in the third and fourth joint surface weld gas or liquid-tight and surrounds the respective cavity or the respective cavities.

Also if the provided on the intermediate part first joining surface in a plan view of the assembly in an outer edge region of the intermediate part lies, could the latter with a Support the area of the intermediate part on the first plastic part, which is not an outer edge region of the intermediate part is. However, embodiments are preferred which the intermediate part with an outer edge region on the first plastic part rests or is supported on this.

in principle could (in a plan view of the assembly) the first and the second joining surface one from the course of third and the fourth joining surface independent Have course, in preferred embodiments of the assembly according to the invention the first and the second joining surfaces run but approximately parallel to the third and fourth joint surface (in a plan view of the assembly).

As has already been indicated above, are preferable to Embodiments of the invention Assembly characterized in that to form the welds the plastic of the three plastic parts in the four joining surfaces melted by means of an energy radiation or a hot gas was, with this hot gas opposite to the molten Plastic should be inert, hence the quality of the welds or welds not by oxidation products or other reaction products can be affected.

Especially recommendable are assemblies according to the invention, in which at least one of the plastic parts, in particular For all plastic parts, the thermoplastic is a polyamide is.

Further Embodiments are preferred in which, for reasons the saving of expensive plastic as well as possible low weight at least the first and / or the second plastic part one by injection molding and simultaneous physical Foaming a plastic melt produced injection molded part is. It has surprisingly been found that is also two foam plastic parts or a foam plastic part and a non-foamed plastic part by hot gas welding connect with each other through a qualitative one high quality weld.

Mentioned Finally, be that an inventive Assembly also include more than three thermoplastic parts can; so it would be possible, for example, two intermediate parts, which extends from the first plastic part in opposite directions stretch away, hang up on the first plastic part and then the second plastic part in inventive Way with the two intermediate parts and the first plastic part to weld.

The The invention also relates to a method for producing an inventive Assembly, which is characterized in that the intermediate part placed on the first plastic part and then the plastic of the Plastic parts melted in the four joint surfaces is what the second plastic part on the one hand and the intermediate part and the first plastic part on the other hand with their joining surfaces be pressed against each other.

there it is particularly advantageous if in the welds to be generated corresponding areas of the three plastic parts of the plastic everywhere is melted at the same time, which is the case with all the above non-contact welding without more is possible and quality everywhere high-quality welds leads.

As already apparent from the above, the hot gas welding is particularly recommended for the inventive method. In hot gas welding, the hot gas jet could be generated by means of a slot nozzle, if the slot shape is adapted to the contour of the weld or weld to be generated. However, embodiments of the method according to the invention are preferred in which the area of a plastic part corresponding to a weld is heated by means of a group of hot gas nozzles, which are arranged according to the shape of the weld to be generated and directed to the plastic part. This is especially preferred when the weld or weld to be generated does not extend in a plane, since then the length of the particular hollow needle-like hot gas nozzles the spatial course of the weld or weld to be produced readily can be adjusted.

In order to in all joining surfaces, over which the plastic parts to be welded together, the plastic easily anywhere and at the same time can be melted, it is recommended for each the joining surfaces a group of hot gas nozzles to use.

For an assembly according to the invention can be Simplify the manufacturing process and with high repeatability Perform that the intermediate part of the first plastic part mechanically is prefixed, in particular by means of a clip connection before marriage the intermediate part with the second outer part or the second Outer part with the first outer part and the intermediate part is welded. This way is easy ensure that the intermediate part both during melting of plastic, as well as in the manufacture of welds or the welds a desired Position on the first outer part and thus opposite the two outer parts of the finished assembly occupies.

Further Features, advantages and details of the invention will become apparent the attached drawings and the following description a particularly advantageous embodiment of the invention Assembly and the method and a welding tool for their production. The invention is based on a as Valve cover designed for a reciprocating internal combustion engine Assembly explained. In the drawing show:

1 an isometric view of three main parts designed as a valve cover assembly according to the invention, namely a shell-like base, a plate-like intermediate part and a hood-like upper part, before joining these three parts together;

2 a front view of the intermediate part;

3 a vertical longitudinal section through the according to 1 right area of the valve cover according to the line 3-3 in 1 ;

4A and 4B the in 3 C section on a larger scale, before the assembly of the upper part, the intermediate part and the lower part ( 4A ) and after joining the three parts ( 4B );

5 a vertical section through peripheral edge portions of the assembled three parts to illustrate the clip connection between the lower part and the intermediate part;

6 a perspective view of a tool for hot gas welding in order to connect the upper part with the lower part and the intermediate part, and

7 a side view of this tool according to 6 seen from the left.

The 1 shows a hood-like top 10 , a plate-like intermediate part 12 and a bowl-like base 14 a valve cover for a reciprocating internal combustion engine. All three parts are plastic parts made of a polyamide, which is the upper part 10 and the lower part 14 According to the invention to act in the MuCell process produced injection molded plastic foam parts, the intermediate part 12 However, a non-foamed plastic part. Furthermore, according to the invention, in particular the upper part 10 and the lower part 14 fiber-reinforced plastic parts, wherein the reinforcing fibers, in particular glass fibers, should be on average a few tenths of a millimeter long.

In the valve cap according to the invention, as will be explained in more detail later, a device for separating engine oil droplets from a gas stream integrated, which is returned from the crankcase of the engine in the intake manifold; Therefore, the valve cover has a Ölabscheidebereich 16 on; Furthermore, the valve cover according to the invention forms a vacuum storage area 18 , for the sake of completeness, it should be mentioned that the formation of the oil separation region 16 both the top 10 , as well as the intermediate part 12 and the lower part 14 are involved (along with other, to be mentioned later components), during the vacuum reservoir area 18 only from the top 10 and the lower part 14 is formed.

The lower part 14 is with screw holes 20 fitted in order to mount the valve cover on the cylinder head of the engine (with the interposition of a seal).

In the top of the base 14 is a frame-shaped, level and horizontally extending support 22 for the intermediate part 12 molded, whose course (in a plan view of the lower part 14 ) to the contour of the periphery of the intermediate part 12 is adapted and the support of the on the lower part 14 placed intermediate part 12 serves.

In the same way is in the top of the base 14 a frame-shaped and horizontally extending support 24 for the top 10 formed. Regarding the design of the two editions 22 and 24 will be described in the following 4A and 4B directed.

The 3 leaves the inventive design of Ölabscheidebereichs 16 to recognize even more clearly, the 3 also components of the valve cover according to the invention shows which in 1 are not shown. The 3 shows the oil separation area 16 the valve cover in a vertical section.

In the oil separation area 16 are in the overall shell-like lower part 14 two oil sumps 30 and 32 molded into which flows from the above-described gas flow separated engine oil, through oil drain holes 34 and 36 of the intermediate part 12 (see also 1 ). To return the separated engine oil in the engine oil circuit of the engine, have the oil sump 30 and 32 drainage openings in their floors 38 and 40 on.

Before discussing the components of the valve bonnet according to the invention serving to separate oil droplets from said gas stream, reference will first be made to FIGS 3 . 4A and 4B described as the top 10 , the intermediate part 12 and the lower part 14 assembled and welded together.

The in 3 denoted by C and in the 4A and 4B on a larger scale cutout leaves the edition 22 of the lower part 14 for a peripheral edge area 42 of the intermediate part 12 detect; on this edition 22 becomes the intermediate part 12 placed in the correct position and by means to be described later on the lower part 14 mechanically fixed. Outside (toward the periphery of the valve cover) of the peripheral edge portion 42 of the intermediate part 12 have the lower part 14 and the top 10 before the welding of the two parts with each other in the circumferential direction of the valve cover extending and aligned ribs 44 and 46 on, where the two outer parts are welded together. Furthermore, the peripheral edge region 42 of the intermediate part 12 at its top, also along the periphery of the intermediate part 12 extending rib 48 in whose area the upper part 10 and the intermediate part 12 be welded together; at the top 10 but also one of the ribs 48 be provided corresponding to this and aligned, not shown in the drawings rib, so that the outer part 10 and the intermediate part 12 can be welded together at these two ribs.

In the 4A and 4B are the four joining surfaces in which the top part 10 with the lower part 14 and the intermediate part 12 with the shell 10 be welded or are, with 50 . 52 . 54 and 56 designated. A first joining surface 50 gets from the top of the rib 48 formed, it lies a second joint surface 52 at the bottom of the shell 10 across from. A third joining surface is from the top of the rib 44 educated; it is a fourth joining surface 56 opposite, which from the bottom of the rib 46 is formed. In the then possibly no longer existing border or joining surfaces 50 and 52 then lies after the welding of the upper part 10 with the intermediate part 12 a first weld, and in the joining surfaces 54 and 56 lies after the welding of the upper part 10 with the lower part 14 a second weld.

Before welding the three parts 10 . 12 and 14 the ribs point to each other 44 . 46 and 48 and optionally on the upper part 10 existing, the rib 48 opposite and described above rib in accordance with 4A vertical direction according to the invention a certain excess on (compared to in 4B shown state after welding the three parts together), so that during hot gas welding after the melting of the plastic in the areas of the four joining surfaces, the three parts 10 . 12 and 14 can be pressed against each other so that they are in the in 4B shown positions are connected relative to each other.

The main advantage of the in the 4A and 4B illustrated arrangement of the four joining surfaces can be seen in that after placing and prefixing of the intermediate part 12 on this and on the lower part 14 the plastic of the three parts in the areas of the four joining surfaces can be melted simultaneously and in one step, and then the upper part 10 against the intermediate part 12 and the lower part 14 pressed and so in a single step both with the intermediate part 12 as well as with the lower part 14 is connected via welded joints.

The gas flow described above, in which fine and very fine oil droplets are dispersed and from which this oil mist is to be deposited in the valve cover according to the invention, passes through a in the 1 and 2 illustrated inlet opening 60 in the bottom of the base 14 from below into the valve cover and then flows through a passage opening 62 (see also the 1 ) from below into the oil separation area 16 of the top 10 , what in 3 was indicated by the arrow F. So that the gas stream to be treated not with already deposited and in the oil pan 30 oil in contact is the lower part 14 with a partition 63 Mistake. In the further course, the gas stream flows through nozzle openings 64 a wall 66 that of the oil separation area 16 of the top 10 and the intermediate part 12 formed cavity of the valve cover in two chambers A and B (see 3 ). The from the nozzle openings 64 generated gas jets then hit one as a whole 68 designated impact wall, which is different from the upper part 10 extends down into the chamber A and at which the gas flow is deflected downward, so that they have a gap between the baffle wall 68 and the intermediate part 12 flows through, as in 3 was indicated by the arrow F '. Subsequently, the gas flow hits a baffle plate 70 which are from the intermediate part 12 hineinerstreckt upward into the chamber A and through which the gas flow is deflected upward so that they over the baffle plate 70 flows away, as in 3 was indicated by the arrow F ''. The gas stream then leaves the chamber A through an opening, not shown in the drawings, in the oil separation area 16 of the top 10 ,

On the upstream side of the wall 66 in the chamber B separated oil droplets flow on the upstream side of the wall 66 down, and this separated oil flows over the drain hole 34 in the oil sump 30 , On the upstream side of the baffle 68 and optionally on the upstream side of the baffle plate 70 drop in the chamber A separated oil droplets or flow also down and get to the intermediate part 12 ; There resulting oil then flows through the drain opening 36 in the oil sump 32 from. The flapper 70 but mainly serves the purpose through the baffle wall 68 isolated and on the intermediate part 12 formed bottom of the chamber to prevent oil from being entrained by the gas stream, but it through the drain opening 36 to expire.

Based on 2 and 5 will now be explained how the intermediate part 12 at the bottom 14 is prefixed, so it when welding the upper part 10 with the intermediate part 12 and the lower part 14 in the correct position on the lower part 14 is positioned. In this context it should be mentioned that the 5 a slightly different periphery of the intermediate part 12 shows as the 3 . 4A and 4B ,

Near the peripheral edge area 42 ' of the intermediate part 12 are at the bottom tongue-like first locking elements 74 molded, and indeed has the intermediate part 12 along its periphery several such spaced apart locking elements 74 on whose lower free ends are made of the in 5 shown position elastically to the left (according to 5 ). To the inside of the wall of the base 14 are like locking lugs designed second locking elements 76 formed, in positions which the positions of the locking elements 74 match if the intermediate part 12 on the lower part 14 is up. Because the locking elements 74 and 76 are provided with oblique sliding surfaces, snap the locking elements 74 under the locking elements 76 one, if one the intermediate part 12 from above on the lower part 14 hangs up and pushes down, so that the above-described locking or clip connection between the intermediate part 12 and the lower part 14 results.

Based on 6 and 7 the basic structure according to the invention of a tool for hot gas welding is explained below, with which in the areas to be welded together (joining surfaces) of the upper part 10 , the intermediate part 12 and the lower part 14 the valve cap according to the invention, the plastic can melt in one step and everywhere at the same time, whereupon the upper part 10 immediately against the intermediate part 12 and the lower part 14 pressed and so welded to these two parts.

That in the 6 and 7 shown and as a whole with 100 designated tool has several compressed gas connections 102 for supplying a gas which is inert and pressurized with respect to the plastic melt, which is in particular nitrogen. The compressed gas flows in a manner not shown in a heat exchanger 104 , which contains at least one not shown electrical heating element, with which the compressed gas when flowing through the heat exchanger 104 is heated. At the top and bottom of the heat exchanger 104 there is a nozzle plate in each case 106 respectively. 108 ; the nozzle plate 106 is with a first group 110 of fine, hollow needle-like hot gas nozzles 112 provided, extending from the nozzle plate 106 extend vertically upward and have at their upper ends fine outlet openings for the hot gas. In the same way is the nozzle plate 108 with a second group 114 of fine, hollow needle-like hot gas nozzles 116 provided, extending from the nozzle plate 108 extend vertically downwards and have at their lower ends fine outlet openings for the hot gas. The hot gas nozzles are removed from the heat exchanger 104 fed with hot gas.

What simplicity in the 6 and 7 was not or only partially shown, are the following features of the tool according to the invention:
After the first and second joining surfaces 50 . 52 lie in a different horizontal plane than the third and fourth joining surfaces 54 . 56 , indicates both the first nozzle group 110 , as well as the second nozzle group 114 two subgroups of hot gas nozzles each 112 respectively. 116 in which the hot gas nozzles of one subgroup are longer than those of the other subgroup or the nozzle openings of one subgroup in another, according to 7 horizontal plane lying as the nozzle openings of the other subgroup. Furthermore, according to the invention, the nozzle openings of a subgroup of the group 110 along a first curve arranged web, the nozzle orifices of the other subgroup of the group 110 along a second curved path, the nozzle openings of a subgroup of the group 114 along a third cam track and the nozzle openings of the other subgroup of the group 114 along a fourth curved path, wherein the course of the first curved path the course of the second joining surface 52 , the course of the second curved path the course of the fourth joint surface 56 , the course of the third curved track the course of the first joint surface 50 and the course of the fourth curved path the course of the third joint surface 54 equivalent. Furthermore, the nozzle openings of the hot gas nozzles of the four subgroups lie in such planes that the tool 100 from the lower part 14 and the intermediate part 12 lifted top 10 between the latter and the lower part 14 including intermediate part 12 insert and position so that the nozzle openings of the different hot gas nozzle subgroups of the joining surfaces associated with the subgroups all have the same small distance, which is preferably of the order of 2 mm. In this context, it has a positive effect that according to the invention produced by the MuCell method upper and lower parts 10 respectively. 14 at least have no significant delays, so that the second, third and fourth joining surface 52 respectively. 54 respectively. 56 are and are in accordance with the 4B horizontal levels.

According to the invention, the nozzle openings of the hot gas nozzles 112 . 116 Diameter in the order of 1 mm, and for parts to be welded together, preferably a polyamide is used whose melting temperature is about 270 ° C; then the tool used for hot gas welding is operated so that the temperature of the gas leaving the hot gas nozzles is in a range from about 350 ° C to about 400 ° C.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 10019300 B4 [0003]
• - EP 1415789 B1 [0003]

Claims (14)

Assembly with at least three thermoplastic parts welded together at welds, in which an intermediate part is arranged as a third plastic part between a first and a second plastic part, characterized in that the intermediate part is supported on the first plastic part and with a second plastic part facing the first joining surface a second joining surface of the second plastic part adjoins that provided on the first plastic part and the second plastic part facing third joining surface adjacent to a fourth joining surface of the second plastic part, and that the welds on the one in the first and second joining surface and on the other in the third and fourth joining surface. Assembly according to claim 1, characterized in that that in a plan view of the assembly, the third and fourth Joint surface next to an edge of the intermediate part lie. An assembly according to claim 1 or 2, characterized that in a plan view of the assembly, the first joining surface lies in an edge region of the intermediate part. Assembly according to claim 3, characterized in that that in a plan view of the assembly, the first joining surface lies in an outer edge region of the intermediate part. Assembly according to one of claims 1 to 4, characterized in that the intermediate part with an outer edge region rests on the first plastic part. Assembly according to one of claims 1 to 5, characterized in that the first and second joining surface approximately parallel to the third and fourth joining surfaces run. Assembly according to one of claims 1 to 6, characterized in that the welds along the first and second joining surface and along the third and fourth joining surface extending welds form. Assembly according to one of claims 1 to 7, characterized in that the formation of the welds the plastic of the three plastic parts in the four joining surfaces by means of an energy radiation or a hot gas was melted, which is opposite to the molten Plastic is inert. Method for producing an assembly after a of claims 1 to 8, characterized in that the Intermediate part placed on the first plastic part and then the Plastic of the three plastic parts at least in areas of one each of the four joining surfaces is melted, whereupon the second plastic part on the one hand and the intermediate part and the first plastic part on the other hand with their joining surfaces be pressed against each other. Method according to claim 9, characterized in that in that corresponding to the welds to be produced Areas of the three plastic parts of the plastic at least in all these areas everywhere at the same time melted. Method according to claim 9 or 10, characterized that of a weld corresponding area of a Plastic part by means of a group of hot gas nozzles is heated, which the shape of the weld to be generated arranged according to and directed to the plastic part. Method according to claim 11, characterized in that that for each of the four joining surfaces a group is used by hot gas nozzles. Method according to one of claims 9 to 12, characterized in that the intermediate part on the first plastic part mechanically prefixed before the intermediate part with the second Plastic part is welded. Method according to claim 13, characterized in that that the intermediate part by means of a clip connection on the first plastic part is prefixed.