DE102011076637A1 - Optimizing weld seams in plastic component including e.g. fuel filter and/or fuel filter housing, by determining weld seam geometry, and determining loading capacity/strength of weld seam defining parameters such as bursting pressure - Google Patents

Abstract

The method comprises determining a weld seam geometry, determining a loading capacity/strength of the weld seam defining parameters such as bursting pressure, selecting a material layer having a minimum thickness, selecting a weld path depending on the fixed material layer, where the material layer and the weld seam geometry are welded, selecting a weld time depending on the material layer, determining the welding parameters as a function of the selected welding process associated with the selected material layer, and determining the parameters depending on a selected welding device. The method comprises determining a weld seam geometry, determining a loading capacity/strength of the weld seam defining parameters such as bursting pressure, selecting a material layer having a minimum thickness, selecting a weld path depending on the fixed material layer, where the material layer and the weld seam geometry are welded, selecting a weld time depending on the material layer, determining the welding parameters as a function of the selected welding process associated with the selected material layer, and determining the parameters depending on a selected welding device and the weld seam geometry such as an amplitude path. The weld path is greater than or less than 0.5 mm. The weld time includes a melting time, a holding time and/or a joining time, where the holding time is 2-4 seconds. The welding process includes: an ultrasonic welding process, which is carried out for a duration of 0.1-2 seconds; a laser welding process, which is carried out for a duration of 0.2-5 seconds; a linear vibration welding process, which is carried out for a duration of 0.2-7 seconds; a spin welding process, which is carried out for a duration of 0.1-10 seconds; a high frequency welding process, which is carried out for a duration of 0.1-5 seconds; a heating element welding process, which is carried out for a duration of 10-20 seconds; a friction welding process; and a high-frequency welding process. The friction welding process is carried out with an amplitude of 1.2 mm. An independent claim is included for a component comprising two parts to be joined together.

Description

The present invention relates to a method for optimizing welds on plastic components. The invention also relates to a container welded together from at least two parts according to the method of the invention.

When welding plastic parts, in particular when welding activated carbon containers, a whole number of boundary conditions and parameters, such as, for example, a bursting pressure and a weld seam geometry, must be taken into account. The weld is thus manufactured depending on this and possibly further boundary conditions and parameters, with the previously known welding process often ignoring essential constraints or only individual parameters are adjusted, but this one in terms of cost, in terms of weld strength and weld geometry and the use of the respective welding device existing relationship is completely disregarded.

The present invention therefore deals with the problem of providing an improved method for the production of welds on plastic components, by means of which in particular a multiplicity of boundary conditions and parameters and, moreover, their interrelationships between these boundary conditions and parameters can be taken into account.

This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea to optimize welds on plastic components by taking into account a variety of constraints and parameters and relationships between these constraints and parameters. The process according to the invention is divided into the following process steps:
First, a weld geometry is determined, which is already predetermined, for example, by design conditions. Subsequently, at least one boundary condition and / or parameter defining the loadability or strength of the weld seam is selected or defined, such as, for example, a bursting pressure. Such a bursting pressure is of particular interest in particular for plastic containers welded together from individual parts, since the loadability, for example, the strength of the weld seam, is ultimately defined by the bursting pressure which is at least assumed. Again, a minimum welding layer thickness is determined depending on the material to be welded, which is preferably about 200 microns in the most commonly used plastics. From a welding layer thickness of, for example, 200 .mu.m, a stable welding zone with sufficient welding strength is formed, since sufficient material of the two components to be joined together can melt and connect to one another. The minimum welding layer thickness of about 200 microns can of course be undercut in some plastics, such as polypropylene (PP) or polyamide 66 (PA66), compared to other plastics with the same welding strength. The weld layer thickness can be derived from the material properties. By means of the minimum welding layer thickness, only the process reliability can be ensured that sufficient material is melted and can bond sufficiently with one another. Depending on the minimum welding layer thickness and depending on the material to be welded and the weld geometry, a welding path is subsequently determined, it being known from empirical investigations that a large increase in the welding path, preferably beyond 0.5 mm, does not significantly improve the welding layer thickness and thus does not improve the weldability Load capacity, for example, the strength of the weld more effected. Nevertheless, the welding path should preferably be maintained at a minimum size of approximately 0.5 mm in order to be able to compensate in particular for existing manufacturing tolerances. Below a value of approx. 0.5 mm, the weld layer thickness drops significantly. After defining the previously mentioned parameters and boundary conditions, such as, for example, weld geometry, load capacity, minimum weld layer thickness and weld path, a welding time is selected, likewise as a function of the minimum weld layer thickness. The welding time may include both an exclusive melting time and a holding and / or joining time. During the melting time, the materials of the components to be joined together are melted, whereas typically in the holding and / or joining time no further melting, but preferably joining and cooling of the components to be joined together takes place. In the empirical investigations, it has been found that, for example, a welding time of approximately 2-4 seconds is optimal, in particular for a friction welding process. From about 2 seconds, the weld layer thickness no longer changes significantly, whereby the weld strength no longer changes significantly after a welding time of about 4 seconds. Of course, the welding time is also dependent on the particular welding process chosen. In the subsequent process step are now to the selected Defined minimum welding layer thickness associated welding parameters depending on the selected welding process and set, for example, an amplitude in a friction welding. At the same time, however, the parameters influenced by the dependence on the selected welding device / welding machine and / or the weld seam geometry are also determined, for example an amplitude path which can be passed back by the welding device in relation to the weld seam geometry. With the method according to the invention, it is thus possible for the first time to detect, bundle and match a multiplicity of boundary conditions and parameters of at least one parameter parameter determining the quality of the weld seam to be produced. In particular, with the method according to the invention it is possible for the first time to set individual parameters of the welding machine or individual parameters of the welding device of the respective welding method to the respective weld seam geometry and thereby to be able to produce an optimum weld seam. In addition, in the method according to the invention, the inclusion of customer and / or product requirements is additionally taken into account, such as, for example, a bursting pressure in the case of a container welded together from two parts, in particular an activated carbon filter container. At the same time, the welding time and thus also a cycle time can be optimized with the method according to the invention, whereby the technical parameters required for the production of a high-quality weld seam can be additionally economically optimized. In general, with the method according to the invention, an optimized production area can be delimited from a significantly broader production area for the production of industrially produced high-quality welds, this best production area being optimized with regard to both economic, technical and qualitative aspects. The goal is a zero error rate.

For the material-dependent minimum welding layer thickness, the following values can preferably be selected: material PA66 PA6GF15 PA6GF30 PA66 PA66GF30 PP Minimum weld layer thickness [μm] 200 200 200 110 110 100 Table: 1 Material-dependent minimum weld layer thicknesses

The minimum welding layer thickness should preferably be 200 .mu.m, since from this range a stable welding resistance develops and, moreover, enough material of the components to be joined together can be melted in order to join together. By comparing the material properties of different materials, it is possible to conclude on a possible weld layer thickness.

• – Ultraschallschweißen,
• – Laserschweißen,
• – Vibrationsschweißen linear,
• – Rotationsschweißen,
• – Hochfrequenzschweißen,
• – Heizelementschweißen.

The method according to the invention for optimizing weld seams on plastic components can be used for the following welding methods and their respective modifications:

• - ultrasonic welding,
• - laser welding,
• - vibration welding linear,
• - spin welding,
• - high frequency welding,
• - Heating element welding.

• – Kraftstofffilter und/oder Kraftstofffiltergehäuse,
• – Ölfilter und/oder Ölfiltergehäuse,
• – Luftfilter und/oder Luftfiltergehäuse,
• – Adsorptionsfilter und/der Adsorptionsfiltergehäuse für ein Adsorptionsfilter zur Adsorption von flüchtigen Schadstoffen,
• – Zylinderkopfhauben,
• – Halter,
• – Kraftstofftank,
• – Wärmetauscherteile,
• – Pumpenteile
• – beliebige zu fügende Teile in einem Kraftfahrzeug,
• – beliebige zu fügende Teile in einem Fahrzeug,
• – beliebige zu fügende Teile in einem Gebäude.

The method according to the invention for optimizing weld seams on plastic components can be used, for example, for the following parts to be joined:

• Fuel filter and / or fuel filter housing,
• - oil filter and / or oil filter housing,
• - air filters and / or air filter housings,
• Adsorption filter and / or adsorption filter housing for an adsorption filter for the adsorption of volatile pollutants,
• - cylinder head covers,
• - holder,
• - fuel tank,
• - heat exchanger parts,
• - Pump parts
• Any parts to be joined in a motor vehicle,
• Any parts to be joined in a vehicle,
• - Any parts to be joined in a building.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

1 a schematic process sequence using the example of a friction-welded connection to be produced,

2 a dependence of a welding strength of a weld on a welding layer thickness,

3 a diagram with a dependence of the welding layer thickness of a welding path for a possible plastic polyamide (PA 6),

4 a diagram with a dependence of the welding layer thickness of a welding time / holding time, again for the plastic 3 .

5 a dependence of the welding layer thickness of an amplitude (oscillation amplitude), for the plastic 3 .

6 a dependence of the welding strength of the weld on a welding pressure as well as the dependence of the welding layer thickness on the welding pressure, again for the plastic 3 ,

• – Ultraschallschweißen,
• – Laserschweißen,
• – Vibrationsschweißen linear,
• – Rotationsschweißen,
• – Hochfrequenzschweißen,
• – Heizelementschweißen.

According to the 1 , a method according to the invention for optimizing weld seams on plastic components is shown with the following method steps:
By way of example, the method is shown using the example of the friction welding process. However, this should not be understood as limiting, but the method according to the invention for optimizing weld seams on plastic components can be used for any suitable welding methods and their respective modifications, preferably for the following:

• - ultrasonic welding,
• - laser welding,
• - vibration welding linear,
• - spin welding,
• - high frequency welding,
• - Heating element welding.

• – Kraftstofffilter und/oder Kraftstofffiltergehäuse,
• – Ölfilter und/oder Ölfiltergehäuse,
• – Luftfilter und/oder Luftfiltergehäuse,
• – Adsorptionsfilter und/der Adsorptionsfiltergehäuse für ein Adsorptionsfilter zur Adsorption von flüchtigen Schadstoffen,
• – Zylinderkopfhauben,
• – Halter,
• – Kraftstofftank,
• – Wärmetauscherteile,
• – Pumpenteile
• – beliebige zu fügende Teile in einem Kraftfahrzeug,
• – beliebige zu fügende Teile in einem Fahrzeug,
• – beliebige zu fügende Teile in einem Gebäude.

Furthermore, the method according to the invention for optimizing weld seams on plastic components is applicable to any parts to be joined, preferably for the following:

• Fuel filter and / or fuel filter housing,
• - oil filter and / or oil filter housing,
• - air filters and / or air filter housings,
• Adsorption filter and / or adsorption filter housing for an adsorption filter for the adsorption of volatile pollutants,
• - cylinder head covers,
• - holder,
• - fuel tank,
• - heat exchanger parts,
• - Pump parts
• Any parts to be joined in a motor vehicle,
• Any parts to be joined in a vehicle,
• - Any parts to be joined in a building.

In the first method step, a weld geometry is first determined or the design requirements required for this are ascertained. In the subsequent process step, at least one parameter defining the load capacity, for example the strength of the weld seam, such as, for example, a bursting pressure, is set and via this the required strength of the weld seam. The strength of the weld is directly dependent on a material-dependent weld layer thickness, according to the 2 It can be clearly seen that, starting from a weld layer thickness of approximately 200 μm, no significant increase in the strength of the weld seam can be expected any more.

Here are according to the 2 drawn two different curves, wherein the upper weld strengths as a function of the weld layer thickness of a reference part concern, whereas the lower curve experience data of different products, ie data relate to a wide variety of welded joints produced by the method according to the invention. The respective reference parts are manufactured under standard conditions. The parts not produced under standard conditions from real production can therefore deviate from the respective reference part. However, it can be clearly seen that significant changes in the welding strength occur up to a welding layer thickness of approx. 200 μm, so that the minimum welding layer thickness of approx. 200 μm can be used safely for all common plastics. Of course, there are also plastics in which the minimum weld layer thickness can be below or even higher, as shown, for example, in Table 1.

In the next method step, a welding path is determined as a function of the material-dependent minimum welding layer thickness, the material to be welded and the weld seam geometry, in which case, for example, the diagram of FIG 3 can serve, from which for a possible plastic, it is clear that from a welding distance of about 0.5 mm, no significant increase in the weld layer thickness and thus no increase in weld strength occurs more. However, the weld path should be greater than 0.5 mm in order to be able to safely compensate for the tolerances occurring in production.

In the subsequent process step, the welding time is selected as a function of the minimum welding layer thickness, wherein the welding time generally from the time for melting the two components to be joined together and the holding time and / or joining time, in which no more heating takes place, but the components only held together and thereby joined together, composed. According to the 4 In this case, the holding time is shown as a function of the welding layer thickness, wherein the 4 should apply specifically to the vibration welding process. In the case of vibration welding, in fact, the welding time is approximately the same as the holding time, since the actual melting of the components to be joined together takes place very rapidly in comparison with the subsequent holding time. It looks quite different in other welding processes, for example in the heating element welding, in which the heating and melting phase is usually much greater than the subsequent holding time and / or joining shows. The term welding time should thus generally mean the sum of the melting time and the joining / holding time. Looking at the 4 , it can be seen that for different welding pressures, the weld layer thickness no longer changes significantly after a holding time of about 2 seconds. It also applies that the welding layer thickness increases with low welding pressure and the same welding time or holding time. From a holding time of about 4 seconds, an increase in the weld layer thickness and thus also an increase in welding strength in a marginal area, so that in particular during vibration welding and the plastic used, the preferably used welding time is between about 2 and 4 seconds. The melting time can be almost unconsidered in comparison to the holding time, so that in the 4 the holding time corresponds approximately to the welding time.

In a further subsequent process step, the welding parameters associated with the selected minimum welding layer thickness are determined as a function of the selected welding method, which is the case in the case of the vibration welding method according to the 5 for the amplitude in millimeters. It is noticeable that the amplitude should be between 1.2 and 1.8 mm. From an amplitude of approx. 1.2 mm, the weld layer thickness no longer changes significantly, whereby the weld layer thickness increases with low welding pressure and the same amplitude. It should be noted here that the tool geometry and the machine parameters should correspond to the weld seam geometry, which is the last step in the process according to the 1 is checked by "checking the proposal with the production". In this last method step, the parameters are thus matched to one another depending on the selected welding device and the weld geometry, for example. An amplitude path of a friction welding device can be set to a width of the weld seam geometry.

After completion of the method according to the invention, the determined welding parameters are fixed and the serial welding of individual components, for example activated charcoal filter containers, can begin. Of course, alternative paths are recorded within the individual process steps, which must be taken if the changes or adjustments required in the respective process step can not be carried out.

With the method according to the invention it is possible for the first time, both component-specific, d. H. Weld seam specific parameters with manufacturing parameters, such as. Welding pressure, welding time, minimum welding layer thickness and welding path to combine and adjust to each other, whereby the production of high-quality welds in series is possible. The method according to the invention is not limited to individual welding methods, such as, for example, friction welding methods or heating element welding methods, but can generally be applied to all known welding methods.

Claims (11)

Method for optimizing weld seams on plastic components, with the following method steps, - definition of a weld geometry, Determining at least one parameter defining the load capacity / strength of the weld seam, such as a bursting pressure, Selection of a material-dependent minimum welding layer thickness, Selection of a welding path depending on the specified minimum welding layer thickness, the material to be welded and the weld seam geometry, Selection of a welding time as a function of the minimum welding layer thickness, Determining welding parameters associated with the selected minimum welding layer thickness as a function of the selected welding method, for example an amplitude in a friction welding method, and - Setting parameters in dependence of a selected welding device and the weld geometry, such as an amplitude path. A method according to claim 1, characterized in that the following values are selected for the material-dependent minimum welding layer thickness, - Polyamide PA6: about 200 μm, Polyamide PA6GF15: about 200 μm, - Polyamide PA6GF30: about 200 μm, - Polyamide PA66: about 110 μm, - Polyamide PA66GF30: about 110 μm, - Polypropylene: approx. 100 μm. A method according to claim 1 or 2, characterized in that the welding path, in particular for polyamide (PA6) is preferably selected to be greater or smaller than 0.5 mm. Method according to one of claims 1 to 3, characterized in that the welding time consists of a melting time and / or a holding and / or joining time, wherein the holding time for polyamide 6 (PA6) preferably about 0.1 to 60 s, more preferably about 2 to 4 s. Method according to one of Claims 1 to 4, characterized in that a friction welding method or an ultrasonic welding method or a laser welding method or a linear vibration welding method or a rotational welding method or a high-frequency welding method is used as the welding method. A method according to claim 5, characterized in that the friction welding method has an amplitude between 1.0 and 1.8 mm, preferably about 1.2 mm. Method according to one of claims 1 to 6, characterized in that the welding time is additionally selected in dependence on the selected welding method and / or the minimum welding layer thickness. Method according to claim 7, characterized in that the following values are selected for the welding process dependent welding time, - ultrasonic welding: about 0.1-2s, - Laser welding: about 0.2-5s, - vibration welding linear: about 0.2-7s, - spin welding: about 0.1-10s, - High frequency welding: about 0.1-5s, - Heating element welding: about 10-20s. A joined from at least two parts to be joined component, wherein the two parts are welded together by the method according to one of claims 1 to 8. Use of the method for optimizing weld seams on plastic components for the following welding methods and their respective modifications: - ultrasonic welding, - laser welding, - vibration welding linear, - spin welding, - high frequency welding, - Heating element welding. Use of the method for optimizing weld seams on plastic components, for example for the following parts to be joined: Fuel filter and / or fuel filter housing, - oil filter and / or oil filter housing, - air filters and / or air filter housings, Adsorption filter and / or adsorption filter housing for an adsorption filter for the adsorption of volatile pollutants, - cylinder head covers, - holder, - fuel tank, - heat exchanger parts, - Pump parts Any parts to be joined in a motor vehicle, Any parts to be joined in a vehicle, - Any parts to be joined in a building.

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