WO1992000842A1

WO1992000842A1 - Weatherstrip and a method and die for the manufacture thereof

Info

Publication number: WO1992000842A1
Application number: PCT/US1991/004613
Authority: WO
Inventors: David A. Hummer
Original assignee: Harvard Industries The Kingston-Warren Corporation
Priority date: 1990-07-03
Filing date: 1991-06-27
Publication date: 1992-01-23
Also published as: AU8194191A

Abstract

An extruded elastomeric weatherstrip (10) is disclosed having a cross-section which is varied along the weatherstrip's longitudinal axis. The weatherstrip includes an anchoring section (12) for securing the weatherstrip (10) to an edge of an opening in a motor vehicle body or a closure element for that opening, and a bulb (14) for providing a seal therebetween. The connection between the bulb (14) and the anchoring section (12), the wall thickness of the bulb, and the length of one of the legs (18, 19) of the anchoring section (12) can all be varied along the weatherstrip's longitudinal axis. A die (50) for manufacturing such a weatherstrip (10) is also disclosed and includes automatically operated stepping motors (91, 92, 93) which receive commands from a controller (100) and during extrusion vary the above-described characteristics of the weatherstrip accordingly.

Description

WEATHER STRIP AND A METHOD AND DIE FOR THE MANUFACTURE THEREOF

Background of the Invention

The present invention relates generally to the field of weatherstripping for the edges of openings in motor vehicle bodies and closure elements for those openings. In particular, the invention pertains to a weatherstrip having a cross section that is varied along the longitudinal length of the weatherstrip.

Extruded elastomeric weatherstrips are commonly used to provide sealing between the edges of openings of motor vehicle bodies and closure elements for those openings. These seals provide protection from air and water passing through door, trunk, and window seams. For the most part, these seals have been manufactured to have a uniform cross section along their entire longitudinal length. Recently, however, weatherstrips have begun to be manufactured having characteristics that are varied along the extrusion axis.

Extruded weatherstrips suitable for these purposes typically are formed of two co-extruded sections. An anchoring section, of relatively ridged elastomeric material, secures the seal to the edge of either the opening in a motor vehicle body or the closure element for that opening. For sealing, co-extruded along with the anchoring section is a sealing section formed of an elastomeric material that is relatively resilient when cured. It is this sealing section, often taking the form of a bulb, that provides the main obstacle to weather passing through the motor vehicle seams.

Uniform cross-section weatherstripping is generally suitable for applications in which the weatherstripping is applied along a flat linear surface. In many applications, however, weatherstripping is applied to curved surfaces of various radii. Often, in these applications, uniform cross-section weatherstrips afford poor sealing capabilities and can be aesthetically unattractive. This results from unnatural deformation such as creasing and flattening, that can occur when the weatherstrip is required to follow a curved path.

Another problem with the application of uniform cross-section weatherstripping arises where the opening in a motor vehicle body and the closure element for that opening are mismatched. To assure effective sealing in the areas where the gaps between these elements widen, known weatherstrips have longitudinally uniform extra thick sealing sections. As a result, there is excess force generated between the opening and closure element in the areas where thinner weatherstrips will suffice. In the case of a door or trunk of a motor vehicle, this can make closing the door or trunk extremely difficult. Yet another problem with known weatherstrips occurs when it is applied to an edge having an irregular profile. This can result in poor sealing in particular areas along the weatherstrip.

No proposed solution has satisfactorily addressed all of the problems associated with the application of weatherstripping to an irregular edge. Increased wall thickness of the sealing section alone is unable to compensate fully for deformation of the weatherstrip occurring when the weatherstrip travels around corners having small radii of curvature.

It is, therefore, an object of the present invention to provide a weatherstrip designed to afford effective sealing along both straight and curved surfaces. Yet other objects are to provide such a weatherstrip that is easily manufactured and to provide a die for the manufacture of such a weatherstrip.

Summary of the Invention

The problems associated with known weatherstrips are greatly relieved by the present invention which is an extruded elastomeric weatherstrip having a cross-section which is varied along the weatherstrip's longitudinal axis. Because its cross-section varies to conform with the contour of the edge to which it is attached, the weatherstrip of the present invention is superior to known weatherstrips both in appearance and function.

The present weatherstrip includes two primary components: an anchoring section, and a bulb. The anchoring section is adapted for securing the weatherstrip to an edge of an opening in an automobile body or a closure element for that opening, while the bulb is designed for providing a seal therebetween. Typically, the anchoring section is formed of a relatively hard curing elastomeric material while the bulb is formed of a relatively soft curing elastomeric material. Optionally, the weatherstrip can be formed to have fingers projecting inwardly from the anchoring section to secure more strongly the weatherstrip to the edge to which it is attached.

In a typical application, the weatherstrip further includes an embedded spine which generally conforms to the cross-section of the anchoring section of the weatherstrip. This enables the weatherstrip to be rigidly deformed to insure proper attachment to the edge along its entire length. The spine may include a series of identical ribs connected by a support running parallel to the weatherstrip's longitudinal axis.

It is an important characteristic of the present invention that the weatherstrip's cross-section is varied along the weatherstrip's longitudinal axis. This is necessary to compensate for deformation which would otherwise occur when the weatherstrip is attached to a non-linear or otherwise irregular edge.

One characteristic of the weatherstrip that can be varied is the length of one of the legs. Since the edges of the legs act as secondary sealing lips, by enabling the length of one of the legs to be varied, the present weatherstrip affords more effective sealing than known weatherstrips. This is especially true in cases where known weatherstrips having legs of a uniform length pull away from the sealing surface due to deformation.

In accordance with the present invention, also varied is the point at which the bulb connects to the anchoring section. This quality is especially useful in accommodating variation in the space between the vehicle body and, for example, a door. By repositioning the connection point between the bulb and the anchoring section in areas where the weatherstrip will be attached to a sealing edge, the present invention allows one to bring the bulb into optimal position to span the space between the body and the door. A further feature of the present weatherstrip that is varied along the weatherstrip's longitudinal axis is the thickness of the wall that forms the bulb. This affords even greater flexibility in combating sealing problems arising as a result of weatherstrip deformation, particularly at corners where conventional weatherstrips may kink or crease.

In another aspect, the invention provides a compact extrusion die for the manufacture of the above described weatherstrip. The die includes a sponge plate which defines an anchoring section aperture corresponding to the basic profile of the weatherstrip. A bulb forming assembly defines a bulb aperture which is positioned in communication with the anchoring section aperture. In accordance with the invention, the bulb forming assembly is movable in relation to the sponge plate and the anchoring section aperture so that the connection point between the bulb and the anchoring section of the weatherstrip can be varied as the weatherstrip is extruded. Additionally, the bulb forming assembly allows the wall thickness of the bulb forming aperture to be varied.

The die also includes a leg extension bracket arranged to control the length of a leg portion of the anchoring section aperture. The leg extension bracket can be manipulated during the extrusion process so that the length of a leg of the weatherstrip is smoothly varied along the weatherstrip's longitudinal axis. In one embodiment of the invention, the positioning of the bulb forming assembly, the wall thickness of the bulb aperture, and the positioning of the leg extension bracket are controlled automatically by a programmable controller.

Another aspect of the invention pertains to a method for producing the above described weatherstrip through use of the above described die. The method includes manipulating the variable features of the die during extrusion and, in certain cases, varying the rate at which extrusion material is fed to the die, to produce a weatherstrip having a cross section which is varied along the weatherstrip's longitudinal axis. In one embodiment, the invention includes manipulating the variable elements of the die in a cyclical fashion so that a weatherstrip is produced the cross-section of which has a specified periodicity along the weatherstrip's longitudinal axis. The weatherstrip can then be separated into a plurality of identical weatherstrips.

These and other advantages of the present invention will be more fully understood by reference to the following detailed description in conjunction with the attached drawing in which like reference numerals refer to like members.

Brief Description of the Drawing

Fig. 1 is a perspective view of a portion of a weatherstrip formed in accordance with the present invention;

Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1;

Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is a front view of an extrusion die constructed in accordance with the present invention useful in manufacturing a weatherstrip of a type shown in Fig. 1;

Fig. 5 is a cross-sectional view of the die shown in Fig. 4 including a cover plate; and

Fig. 6 is a schematic representation of the die of the present invention positioned in an extrusion head linked to a control system.

Detailed Description

In one aspect, the present invention provides a weatherstrip for use between an opening in a motor vehicle body and a closure element for that opening. The weatherstrip includes a U-shaped anchoring section for securing the weatherstrip to an edge and a bulb connected to the anchoring section for providing a seal. It is an important feature of the invention that the cross-section of the weatherstrip is varied along the weatherstrip's longitudinal axis.

There is shown in Fig. 1 a portion of a weatherstrip 10 constructed in accordance with the present invention. The weatherstrip 10 includes a U-shaped anchoring section 12 connected to a bulb 14 consisting of a tube defined by a wall 16. To form the weatherstrip 10, the anchoring section 12 is extruded simultaneously with the bulb 14. Typically, the anchoring section 12 will be formed so that it cures to be hard in relation to the bulb 14. This is done by extruding the anchoring section 12 as solid material while extruding the bulb 14 with specified air content. Materials such as butyl, styrene-butadiene, and ethylene-propylene rubbers, having a durometer hardness in the range of 40 to 90, have been found to be particularly effective for both the anchoring section 12 and the bulb 14. Of course, other suitable materials may be used. The manner in which the weatherstrip may be extruded from at least two different elastomeric materials simultaneously, is discussed in greater detail hereinbelow. The anchoring section 12 primarily comprises two legs 18 and 19 which are connected by a base 20. The end of the leg 18 distal to the base 20 serves as secondary sealing surface 26. This provides a secondary sealing capability in a addition to that of the bulb 14.

Forming an integral part of the anchoring section 12 is an imbedded spine 22. The spine 22 is formed of a non-elastomeric material, typically metal such as cold rolled steel or aluminum, that is capable of being rigidly deformed. This facilitates attachment of the weatherstrip 10 to, for example, the edge of an opening in an automobile body. In a preferred embodiment of the invention, the anchoring section 12 further includes inwardly projecting fingers 24. These fingers 24 grip the edge to which the weatherstrip 10 is attached to prevent inadvertent detachment.

It is an important feature of the weatherstrip 10 that its cross-section is varied along the weatherstrip's longitudinal axis C. To compensate for deformation which might otherwise occur when the weatherstrip 10 is attached to an irregular edge, at least two characteristics of the weatherstrip's cross-section can be smoothly varied as the weatherstrip 10 is extruded. That is, in accordance with the present invention any combination of: the length of the leg 18; the thickness of the bulb wall 16; and the connection point of the bulb 14 to the anchoring section 12 can be varied. There is shown on Figure 2 a cross-section of the weatherstrip 10 taken along line 2-2 of Figure 1. At this portion of the weatherstrip 10, the leg 18 has a length from a top surface of the base 20 to the secondary sealing lip 26 of L. By viewing the weatherstrip cross-section at a different point along the longitudinal axis C, it is evident that the length L is not uniform along the longitudinal axis of the weatherstrip.

Shown in Figure 3 is such a view. At this portion of the weatherstrip 10, the length of the leg 18 is now L* which is longer than L. Such an increase in the leg length facilitates improved sealing in areas where the weatherstrip 10 might experience deformation due to being attached to an irregular surface. By providing that the length L* of the leg 18 is only as long as need be, depending upon the contour of the edge to which the weatherstrip 10 is attached, effective sealing is achieved in all areas without using unnecessary amounts of elastomeric material.

Another feature of the weatherstrip 10 that is not uniform along the weatherstrip's longitudinal axis C is the distance h from the top surface of the base 20 to the point .at which the bulb 14 is connected to the anchoring section 12. Namely, the distance h' shown in Figure 3 is greater than the distance h shown in Figure 2. By varying this distance, one can position the bulb 14 with respect to the leg 19 such that the bulb 14 is positioned ideally to fit the space between the body opening and the door or other closure element. That is, in the weatherstrip 10, the distance h can be reduced or increased so that the bulb 14 comes into alignment with the space to be sealed.

A third feature of the weatherstrip 10 which is varied along the longitudinal axis C is the thickness of the wall 16. In extreme cases where the bulb 14 might tend to pull away from the surface to which it is intended to seal, to insure proper sealing the thickness of the wall 16 can be increased such as at 16'. By providing that the thickness of the wall 16' is only increased in areas in which an increased thickness is required, the present invention provides effective sealing while optimizing use of the extrusion material and minimizing the amount of force required to close the closure element in the opening in the motor vehicle body around which the weatherstrip 10 is applied.

There is shown in Figure 4 a front view of a compact extrusion die 50 suitable for manufacturing the weatherstrip 10. The die 50 includes a sponge plate 58 and a sponge plate extension 58'. The phrase "sponge plate" is used because typically the elastomer extruded through it is a thermoplastic sponge rubber. Of course, other extrudable material may be used. The sponge plate 58 defines a leg extension bracket guide 84 within which a leg extension bracket 64 can reciprocate. The sponge plate 58 also defines an anchoring section aperture 66 corresponding to the profile of the U-shaped anchoring section 12. Projecting inwardly from the anchoring section aperture 66 are finger apertures 67 for forming the inwardly projecting fingers 24 of the anchoring section 12 of the weatherstrip 10. In cooperation with the sponge plate extension 58', the sponge plate 58 defines a channel 59 within which a bulb forming assembly 74 is able to travel back and forth. The bottom surface of the channel 59 is defined by a dense plate 62.

The bulb forming assembly 74 includes a bulb location adjusting bracket 52, a bulb wall thickness adjusting bracket 54, and a bulb slide 56. These three elements cooperate to determine the point at which the bulb 14 joins the U-shaped anchoring section 12, as well as the thickness of the bulb wall 16.

The bulb slide 56 defines an air flow channel 51 having a outflow port 53. An end of the air flow channel 51 communicates with a chamber 55 defined by the sponge plate 58. An air input port 57 communicates with the chamber 55 and affords access thereto. During extrusion from the die 50 of a weatherstrip, air is forced under pressure, typically equivalent to approximately a 6 inch column of water, through the air input 57 into the chamber 55. From the chamber 55 the air flows into the channel 51 and exits from the outflow port 53. The outflowing air creates sufficient pressure in the portion of the extrudate forming the bulb 14 to prevent the extrudate from collapsing prior to curing. In this manner, the geometry of the bulb 14 is maintained.

The positioning of the bulb forming assembly 74 in relation to the anchoring section aperture 66 is controlled by a bulb forming assembly shaft 68. The shaft 68 is threaded and passes through a threaded bore (not shown) in a block 76 which is rigidly attached to a dense plate 62. The dense plate 62 supports the sponge plate 58 and the sponge plate extension 58' and is immovable in relation thereto. Accordingly, by rotating the threaded shaft 68 with respect to the block 76, the bulb forming assembly 74 will correspondingly be moved with respect to the sponge plate 58 and the anchoring section aperture 66. In this manner, the connection point between the bulb 14 and the U-shaped anchoring section 12 along the leg 19 can be determined.

The chamber 55 is long enough so that the channel 51 is always in communication with the chamber 55 during extrusion of a weatherstrip. That is, no matter what position along the leg 19 is selected as the connection point between the bulb 14 and the anchoring section 12, air is able to flow from the chamber 55 into the channel 51. This enables one to prevent collapse of the bulb 14 prior to curing of the extrudate by forcing pressurized air out of the port 53 regardless of the selected connection point between the bulb 14 and the U-shaped anchoring section 12.

It is clear, therefore, that in accordance with the present invention, by rotating the threaded shaft 68 as the weatherstrip 10 is extruded from the die 50, the weatherstrip's profile can be varied with regard to the height h. As discussed above, this variability allows a weatherstrip to be manufactured that overcomes the problems associated with bulb misalignment. By varying the height h over portions of the weatherstrip 10, a weatherstrip can be manufactured in which the point of attachment of the bulb 14 to the leg 19 is varied along the length of the weatherstrip to fill the space to be sealed at all points

An additional feature of the weatherstrip 10, is that the thickness of the bulb wall 16 of the bulb 14, can be varied along the weatherstrip's longitudinal axis C. This thickness variation is controlled by varying the position of a wall thickness adjusting bracket 54 with respect to the bulb slide 56 and the bulb adjusting bracket 52. This positioning is controlled by a threaded wall thickness adjusting bracket shaft 70.

The threaded shaft 70 is arranged in registration with a threaded bore (not shown) in a block 78 which is rigidly secured to the wall thickness adjusting bracket 54. Accordingly, when the threaded shaft 70 is rotated relative to the block 78, the wall thickness adjusting bracket 54 is made to move longitudinally with respect to the threaded shaft 70. This results in the wall thickness adjusting bracket 54 also moving with respect to the bulb slide 56 and the bulb adjusting bracket 52. In this manner, the bulb wall aperture 80 is either widened or narrowed accordingly.

By rotating the threaded shaft 70 during extrusion of the weatherstrip 10, therefore, the thickness of the wall 16 of the bulb 14 is varied along the weatherstrip's longitudinal axis C. This enables one to increase bulb thickness at selected intervals to in turn allow the seal to follow tight corners without bulb distortion which might permit wind and water leakage. This feature of the weatherstrip 10 also enables a manufacturer to use increased sealing material only in those areas where it is necessary. As a result, a seal can be easily manufactured having a wall thickness that is varied to correspond with the varied spacing between the edge of an opening and the edge of a closure element for that opening. So, for example in the case of a door and an opening in a motor vehicle body, the force generated by closing the door is evenly distributed, even where the door and the body are not perfectly aligned.

A third characteristic of the weatherstrip 10, which can be varied along the weatherstrip's longitudinal axis C through the use of the die 50, is the length L of the leg 18. By moving the leg extension bracket 64 either toward or away from the center of the die 50, the length L of the leg 18, of the weatherstrip 10 can be controlled. That is, as the leg extension bracket 64 is moved toward the center of the die 50 it will block off a portion of the aperture 66. As a result, extrudate will be prohibited from flowing through part of the aperture 66, thereby shortening the leg 18 of the extruded weatherstrip.

Movement of the leg extension bracket 64 is effected in the same manner as is movement of the bulb forming assembly 74. That is, a threaded shaft 72 is in registration with a threaded bore in a block 82 which is rigidly affixed to the leg extension bracket 64. By rotating the shaft 72 with respect to the leg extension bracket 64, therefore, the leg extension bracket 64 can be made to reciprocate within the leg extension bracket guide 84. This rotation of the leg extension shaft 72, like the rotation of the bulb adjusting bracket shaft 68 and the wall thickness adjusting bracket shaft 70, is preferably controlled by stepping motors. This is described in greater detail below.

The extension shaft 72 is supported at its forward end by a block 100 which is rigidly affixed to a cover plate 60. The block acts as a bearing so that the shaft 72 does not experience movement in the longitudinal direction. Accordingly, since the shaft 72 is in registration with a threaded bore defined by the block 82, the rotation of the shaft 72 is translated to a longitudinal movement of the leg extension bracket 64 to either lengthen or shorten the leg portion of the anchoring section aperture 66. As with the other variable features of the weatherstrip 10, this allows the length of the leg 18 to be smoothly varied during the extrusion process.

This provides great flexibility in manufacturing a weatherstrip that is perfectly suited for the application in which it is to be used. Advantages of this process include optimizing the use of elastomeric material, improving the sealing capability of the weatherstrip, and improving the aesthetic appearance of the installed weatherstrip. It is an important feature of the invention that these three features of the weatherstrip's profile. namely leg length L, bulb positioning height H, and the thickness of the wall 16, can be smoothly varied both independently and in combination.

Figure 5 shows a cross-section of the extrusion die 50 taken at line 5-5 of Fig. 4, and the housing cover plate 60 which, for the most part, is omitted from Fig. 4 for clarity of explanation. A dense funnel plate 86 forms the bottom of the die 50 and supports above it a sponge funnel plate 88. The dense funnel plate 86 defines an orifice 87 for receiving a flow of thermoplastic elastomeric material in the direction of arrow D. The sponge funnel plate 88 defines an orifice 89 for receiving a flow of thermoplastic elastomeric material in the direction of arrow S. The elastomeric material which is fed into the orifice 87 can vary in density or other mechanical properties from that fed into the orifice 89. This permits one to form an extrudate that, for example, is stiffer than that formed from the thermoplastic elastomeric material which is fed to the orifice 89.

As shown in Fig. 5, the dense elastomeric material will follow a path from the orifice 87 up through and circumferentially about the center axis 67 of the extrusion die 50 until it eventually comes into contact with the metal spine 22 which is fed simultaneously through a guide 102 projecting coaxially up from the bottom of the die 50. The dense elastomeric material then exits the die 50 through the aperture 66 at the top of the die 50 to form the anchoring section 12 of the weatherstrip 10. The spine 22 which is imbedded in the anchoring section 12 of the weatherstrip 10 includes a series of identical ribs 104 generally conforming to the cross-section of the anchoring section 12 and connected by a support 106 running parallel to the weatherstrip's longitudinal axis C.

Simultaneously, a different (or the same), e.g., lower density, elastomeric material is pumped from the orifice 89 to an annular volume 189 and up in the direction of arrow 190 through the die 50. The lower density elastomeric material exits the extrusion die 50 through the bulb forming aperture 80 to form the bulb portion 14 of the weatherstrip 10. As discussed above, during extrusion, characteristics of the extrusion die 50 will be varied to form a weatherstrip that is perfectly suited for the particular application in which it is to be used.

In Figure 6 there is shown a schematic representation of the die 50 and a control means therefor. As mentioned, the threaded shafts 68, 70, and 72 are controlled by stepping motors 91, 92, and 93, respectively. It is preferred to control the stepping motors using an automatic control system which cycles the die through a series of regular movements. This enables production of a continuous extrudate having serially repeated identical segments which subsequently can be cut to produce identical weatherstrips each of which is varied as desired in cross-section along its length. Alternatively, in a single cycle, left and right side weatherstrips can be extruded an cut to form matching pairs. For purposes of illustration, the stepping motors 91, 92, and 93 are shown as controlled by a digital programmable controller 100. A series of commands can be inputed to the programmable controller 100 to actuate the stepping motors during extrusion of the weatherstrip 10 in a manner ordinarily known in the art, so that the weatherstrip's cross-section is varied along its longitudinal axis appropriately. By instituting a series of commands cyclically, an extrudate can be produced having a cross-section of specified periodicity. This will enable the extrudate to be divided into a plurality of identical extrudates, each of which has a cross-section which is varied along its longitudinal axis.

It should be understood that the above description pertains to an illustrative embodiment of the present invention. Various alterations will be obvious to those skilled in the art, yet remain within the spirit and scope of the invention. The invention is to be defined, therefore, not by the preceeding description, but by the claims that follow.

What is claimed is:

Claims

1. An elastomeric weatherstrip for use between an irregular edge of an opening in a body of a motor vehicle and a closure element for that opening comprising:

an extrudate having a longitudinal axis and defining,

an anchoring section having two legs connected to a base so as to form a substantially U-shaped cross section, the length of one of said legs being varied along the longitudinal axis in a direction perpendicular to the longitudinal axis, and

a bulb comprising a bulb wall connected to one of said legs at a position which is varied along the longitudinal axis,

said bulb wall being varied in thickness along the longitudinal axis.

2. A weatherstrip as set forth in claim 1 wherein said anchoring section is formed of a first elastomeric material and said bulb is formed of a second elastomeric material, said first elastomeric material being stiffer than said second elastomeric material.

3. A weatherstrip as set forth in claim 1 further comprising a plurality of fingers projecting inwardly from said legs.

4. A weatherstrip as set forth in claim 1 further comprising a malleable spine formed of a non-elastomeric material which is co-extruded with said extrudate and forms an integral part of said anchoring section.

5. A weatherstrip as set forth in claim 4 wherein said spine is formed of a series of ribs connected along a support which is parallel to the longitudinal axis, said ribs generally conforming to said anchoring section.

6. A die for the extrusion along a longitudinal axis of a weatherstrip having a cross section which is varied along that axis, the die comprising:

a plate defining a substantially U-shaped anchoring section aperture;

a leg extension bracket capable of obstructing a portion of said aperture for varying the length of said aperture; and

a bulb forming assembly defining a bulb aperture in communication with said anchoring section aperture, said bulb forming assembly being movable with respect to said plate so that said bulb aperture connects to said anchoring section aperture at a position which is variable.

7. A die for the extrusion along a longitudinal axis of a weatherstrip having a cross section which is varied along that axis, the die comprising: a plate defining a substantially U-shaped anchoring section aperture;

a leg extension bracket capable of adjustably obstructing a portion of said aperture for varying the length of said aperture; and

a bulb forming assembly defining a bulb aperture in communication with said anchoring section aperture, the bulb forming assembly including an adjustable bulb wall thickness adjustment bracket for varying the thickness of a portion of said bulb aperture.

8. A die for the extrusion along a longitudinal axis of a weatherstrip having a cross section which is varied along that axis, the die comprising:

a plate defining a substantially U-shaped anchoring section aperture; and

a bulb forming assembly defining a bulb aperture in communication with said anchoring section aperture, said bulb forming assembly being movable with respect to said plate so that said bulb aperture connects to said anchoring section aperture at a position which is variable, said bulb forming assembly further including an adjustable bulb wall thickness adjustment bracket for varying the thickness of a portion of said bulb aperture forming the bulb wall.

9. A die as set forth in claim 8 further comprising a leg extension bracket capable of adjustably obstructing a portion of said aperture for varying the length of said aperture.

10. A die as set forth in claims 6, 7, or 8 wherein said plate further defines a plurality of finger apertures extending inwardly from said anchoring section aperture.

11. A die as set forth in claims 6, 7, or 8 further comprising a guide for feeding a nonelastomeric spine through said anchoring section aperture during extrusion of the weatherstrip.

12. A die as set forth in claims 6, 7, or 8 further comprising a first flow path for feeding a first elastomeric material to said anchoring section aperture and a second, separate, flow path for feeding a second elastomeric material to said bulb section.

13. A method for extruding along a longitudinal axis an elastomeric weatherstrip having a cross section which is varied along that axis, the method comprising the steps of:

providing an extrusion die as set forth in claim 6;

delivering a thermoplastic elastomeric material to the anchoring section aperture and to the bulb aperture to extrude from the die a formed weatherstrip; adjusting during extrusion the leg extension bracket to vary the overall length of the anchoring section aperture; and

adjusting during extrusion the bulb forming assembly with respect to the plate to vary the position of the bulb aperture with respect to the anchoring section aperture.

14. A method for extruding along a longitudinal axis an elastomeric weatherstrip having a cross section which is varied along that axis, the method comprising the steps of:

providing an extrusion die as set forth in claim 7;

delivering a thermoplastic elastomeric material to the anchoring section aperture and to the bulb aperture to extrude from the die a formed weatherstrip;

adjusting during extrusion the leg extension bracket to vary the overall length the anchoring section aperture; and

adjusting during extrusion the bulb wall thickness adjusting bracket to vary the thickness of a portion of the bulb aperture defining the bulb wall.

15. A method for extruding along a longitudinal axis an elastomeric weatherstrip having a cross section which is varied along that axis, the method comprising the steps of: providing an extrusion die as set forth in claim 8;

adjusting during extrusion the bulb wall thickness adjustment bracket to vary the thickness of a portion of the bulb aperture; and

16. A method for extruding along a longitudinal axis an elastomeric weatherstrip having a cross section which is varied along that axis, the method comprising the steps of:

providing an extrusion die as set forth in claim 9;

adjusting during extrusion the bulb wall thickness adjusting bracket to vary the thickness of a portion of the bulb aperture forming the bulb wall; adjusting during extrusion the position of the bulb forming assembly to vary the position of the bulb aperture with respect to the anchoring section aperture; and

adjusting during extrusion the leg extension bracket to vary the overall length of the anchoring section aperture.

17. A method as set forth in one of claims 13 through 16 wherein the thermoplastic elastomeric material which is delivered to said anchoring section aperture is different from the thermoplastic elastomeric material which is delivered to said bulb aperture.

18. A method as set forth in one of claims 13 through 16 further comprising the step of:

feeding a spine through the anchoring section aperture and extruding it from the die along with the formed weatherstrip so that it forms an integral part of the anchoring section of the weatherstrip.

19. A system for producing an extrudate having a cross-section which is varied along the extrudate's longitudinal axis comprising:

an extrusion die defining an extrusion aperture, at least two cross-sectional aspects of which are variable; means for varying said cross-sectional aspects of said extrusion aperture; and

means for automatically controlling cyclically said means for varying said cross-sectional aspects so that an extrudate can be produced the cross-section of which has a periodicity along the extrudate*s longitudinal axis, thereby allowing said extrudate to be divided into a plurality of identical extrudates each of which has a cross-section which is varied along its longitudinal axis.

20. A system as set forth in claim 19 wherein said means for automatically controlling cyclically said means for varying said cross-sectional aspects of said extrusion aperture is a programmable controller.