EP1560690A2

EP1560690A2 - Weather strip and method of manufacturing same

Info

Publication number: EP1560690A2
Application number: EP03776544A
Authority: EP
Inventors: John Bester; Jeffrey Budd; Raymond M. Fetcenko; Alex Wong
Original assignee: Nordson Corp
Current assignee: Nordson Corp
Priority date: 2002-10-31
Filing date: 2003-10-24
Publication date: 2005-08-10
Also published as: AU2003284155A8; WO2004041497A2; CA2499444A1; MXPA05004042A; EP1560690A4; AU2003284155A1; WO2004041497A3

Abstract

A method of manufacturing a weather strip (10) which includes forming a compressible bulb member (12) having a hollow interior (14). A liquid thermoplastic material (34), such as a hot melt material, is injected into the hollow interior (14). The thermoplastic material (34) cures into a resilient plug (40) to provide reinforcement to one or more locations along the length of the weather strip (10).

Description

WEATHER STRIP AND METHOD OF MANUFACTURING SAME

Field of the Invention

The present invention generally relates to weather strips and,

more particularly, methods for reinforcing portions of the weather strip at areas

of high stress concentration such as at curves in the weather strip.

Background of the Invention

Many varieties of weather strips are used, for example, in door,

window, and hatch assemblies for sealing the interior of a structure against the

elements. For example, in automotive applications, weather strips have been

used to seal around the windows, the doors, the trunk and the hood of a

vehicle to prevent water and air from entering interior areas of the automobile

at these locations. Weather strips of this type are typically extruded from

natural or synthetic rubber, such as ethylene-propylene-diene (EPDM) rubber.

The extruded weather strip may be cured by heat and then cooled in a water

bath prior to being cut to a desired length. Often, the weather strips are

configured into a closed loop or other curved shape to fit properly at the

desired location, such as between the trunk frame and the trunk lid, or at other

locations such as the hood area, door frame, window frame, etc. The weather

strip may be permanently thermoformed during the manufacturing process into

the desired curved shape to ease the assembly process when the weather strip

is later secured to its supporting structure. In many cases, it is necessary to reinforce portions of the weather

strip, for example, to ensure that the shape and integrity of the bulb member is

maintained and does not crease or kink during application to supporting

structure, such as a window, door, trunk or hood structure. This is especially

important at locations having a sharp bending or curving radius since the bulb

member is most prone to kink and therefore leak at these locations. Such

reinforcement can also ensure adequate sealing performance over long periods

of use. As shown in Fig. 1 , various types of tubular foam plugs 1 8 are

currently inserted into the hollow interior 14 of a bulb member 1 2 associated

with the weather strip 10. These tubular plugs 1 8 are usually about 4-8

inches long and are preformed from a relatively rigid, but resilient foam

material. The plugs 1 8 are forced into the hollow interior 1 4 of bulb member

1 2 by either a rod 20 or by using pressurized air. These plugs typically

increase the force to compress the bulb member 1 2 by 1 0N to 30N depending

on the application. Fasteners, such as rivets (not shown), may be punched

through the weather strip and into the tubular plug to prevent shifting of the

plug after insertion. The plugs also may be fastened by other means, such as

by structure on the plug itself or through the use of adhesive. Weather strip

1 0 is secured to supporting structure, such as a window frame, using a U-

shaped carrier or channel portion 1 6. The plugs must be inserted accurately so

that they are positioned at the location or locations along the length of the

weather strip which will be subjected to higher stress concentrations, such as

at the corners of the window frame. To accomplish this, manufactures may position a clamp at the desired location along tne weather strip to function as

a stop as the plug is pushed into the hollow interior of the bulb member.

The insertion of solid foam plugs into weather stripping generally

as described above is a time consuming procedure which therefore increases

production costs. Other problems can also arise such as the inaccurate

placement of the plug within the weather strip or axial shifting of the plug after

insertion due to inadequate fixation thereof within the weather strip.

To address the above problems as well as other problems in this

art, there is a need for a reinforced weather strip and manufacturing method

which reduce manufacturing time and costs, while also ensuring optimum

sealing performance over the necessary product life.

Summary of the Invention

In one aspect, the invention generally relates to a method of

manufacturing a weather strip generally involving the injection of a

thermoplastic liquid into the hollow interior of a compressible bulb member.

The liquid thermoplastic material at least partially cures into a resilient plug

within the hollow interior. Preferably, the liquid thermoplastic material is a hot

melt material and, more specifically, a tool dip like hot melt material which

may be solid (i.e., non-foamed) or foamed. This material has been found to

provide the necessary combination of compression resistance and resilience

during use. The liquid thermoplastic material may De mjecτeα oy first forming

a hole in the bulb member and then inserting a thermoplastic material injecting

member through the hole and into the hollow interior. The hole may be formed

by the injecting member itself or preformed by another implement. The

compressible bulb member is formed preferably by extruding EPDM. The liquid

thermoplastic material is preferably injected only along a portion of the length

of the bulb member and, more preferably, at a portion or portions of the length

which will experience higher stress concentration or pressure during assembly

and/or use, such as at curved locations along the length of the weather strip.

The invention further contemplates a weather strip comprising a

compressible bulb member having a hollow interior and a resilient

thermoplastic material located in the hollow interior. The weather strip can

include one or more of the various features and aspects as generally described

above.

These and other features and objectives of the present invention

will become more readily apparent from the following detailed description

taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is an elevational view, partially cross sectioned, illustrating

a prior art method of reinforcing a weather strip. Fig. 2A is an elevational view, partially cross sectioned,

illustrating a method of manufacturing a weather strip in accordance with a

preferred embodiment of the invention.

Fig. 2B is a cross sectional view taken along line 2B-2B of Fig.

2A.

Fig. 3A is an elevational view, partially cross sectioned,

illustrating a portion of the weather strip reinforced in accordance with the

preferred embodiment of the invention.

Fig. 3B is a cross sectional view taken along line 3B-3B of Fig.

3A.

Detailed Description of Specific Embodiments

Turning to Figs. 2A and 2B, a hot melt adhesive dispensing gun

30 receives thermoplastic hot melt material from a heated hose 32 and

dispenses the material 34 through a valve 36 having a discharge portion or

injecting member 38. Discharge portion 38 may be constructed so as to

pierce bulb member 1 2 under a sufficiently applied force. Discharge portion

38 may be formed in various manners to allow easier piercing to be

accomplished, such as through the use of a needle-shaped discharge portion

38 or a lance or knife-like component coupled to the discharge portion 38. It

may also be easier to inject hot melt material 34 at the base of bulb member

1 2 adjacent to carrier or channel 1 6. Channel 1 6 is a relatively rigid

component and, therefore, there will typically be more support at this area to allow a puncture to be made. Alternatively, a hole may be preformed through

bulb member 1 2 such that discharge portion 38 simply needs to be inserted

through the performed hole prior to injecting hot melt material 34.

Hot melt material 34 is preferably injected along only a portion of

the length of weather strip 10 such as along a portion that is or will later be

curved as shown in Figs. 3A and 3B. Other areas which represent high

pressure points or areas of higher stress concentration may also utilize the

principles of this invention. During the injection process, the desired area to be

filled with liquid hot melt material 34 may be sealed off on both ends thereof,

for example, by applying clamps (not shown) or through other methods.

Alternatively, and as illustrated in Fig. 2A, the hot melt material 34 may spread

out in both directions upon injection in order to fill the desired length of hollow

interior 14 after dispensing for a predetermined time at the appropriate flow

rate. The hot melt material 34 may be introduced at one or more locations

along weather strip 10 using one or more dispensers such as guns 30.

Multiple introduction locations would be necessary to form multiple spaced

apart plugs of material, or may be necessary or desirable to form a single

relatively long plug of material. Multiple introduction locations may be

achieved using the same gun or multiple guns. To provide further structural

support for bulb member 1 2, suitable fixturing may be provided to hold and

support at least a portion of the outer surface thereof. This would prevent

bulb member 1 2 from expanding diametrically and, as a result, either splitting or lessening the lengthwise movement of hot melt material 34 along bulb

member 1 2.

Once cured as shown in Figs. 3A and 3B, the liquid hot melt

material 34 becomes a resilient solid plug 40 which can receive a significantly

higher compression force "F" and offer greater compression resistance than

non-reinforced areas of weather strip 10. Preferably, for automotive

applications, plug 40 will increase the force to compress bulb member 1 2 by

about 1 0N to about 30N, however, this may change depending on the

application. The reinforced area is still resilient enough to allow weather strip

1 0 to properly perform its sealing function over the necessary product life. It

has been found that the inventive method of injecting a hot melt material takes

only a few seconds as compared to approximately 90 seconds for solid foam

plug insertion. Labor cost savings is also significant as a reduction of

operators is also realized as a result of the invention. In such applications, a

plug length of about 1 00mm to about 400mm is preferred, however, this may

be readily changed based on application needs. The preferred hot melt

material is product no. H561 -B of Heartland Adhesive Co., Germantown, Wl.

However, other foamed or non-foamed thermoplastic materials, such as other

solid hot melt materials, may be used instead. Use of foamed materials may,

for example, enable a lower durometer bulb 1 2.

While the present invention has been illustrated by a description

of a preferred embodiments and while these embodiments have been described

in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages

and modifications will readily appear to those skilled in the art. The various

features of the invention may be used alone or in numerous combinations

depending on the needs and preferences of the user. This has been a

description of the present invention, along with the preferred methods of

practicing the present invention as currently known. However, the invention

itself should only be defined by the appended claims.

Having described the invention, what is claimed is:

Claims

A method of manufacturing a weather strip, comprising:

providing a compressible bulb member having a hollow interior,

injecting a liquid thermoplastic material into the hollow interior,

and

allowing the liquid thermoplastic material to at least partially cure

into a resilient plug within the hollow interior.

2. The method of claim 1 , wherein the liquid thermoplastic material

comprises a hot melt material.

3. The method of claim 1 , wherein injecting the liquid thermoplastic

material further comprises:

forming a hole in the bulb member, and

inserting a thermoplastic material injecting member through the

hole and into the hollow interior.

4. The method of claim 3, wherein providing the compressible bulb

member further comprises extruding the compressible bulb member.

5. The method of claim 3, further comprising:

using the injecting member to pierce the hole in the bulb member.

6. The method of claim 1 , wherein the bulb member has a length

and the liquid thermoplastic material is injected along only a portion of the

length.

7. The method of claim 1 , further comprising:

forming the bulb member into a curved shape at the location of

the resilient plug.

8. The method of claim 1 , wherein the weather strip includes a

carrier member coupled to a base of the bulb member, and the method further

comprises:

injecting the liquid thermoplastic material at the base of the bulb

member.

9. A weather strip comprising:

a compressible bulb member having a hollow interior, and

a resilient thermoplastic material located in said hollow interior.

1 0. The weather strip of claim 9, wherein said resilient thermoplastic

material comprises a hot melt material.

1 1 . The weather strip of claim 9, wherein said compressible bulb

member further comprises an extruded rubber material.

1 2. The weather strip of claim 1 i , wnerem saiα extruαeα ruooer

material comprises EPDM and said resilient thermoplastic material comprises a

solid hot melt material.

1 3. The weather strip of claim 9, wherein said bulb member has a

length and said resilient thermoplastic material is located along only a portion

of said length.

1 4. The weather strip of claim 9, wherein said bulb member includes

at least one curve extending along said length and said resilient thermoplastic

material is located at said curve.