WO1998023416A1

WO1998023416A1 - Cutting assembly for removing windshield

Info

Publication number: WO1998023416A1
Application number: PCT/CA1997/000902
Authority: WO
Inventors: Alfred John Ogston
Original assignee: Crystal Glass Canada Ltd.
Priority date: 1996-11-28
Filing date: 1997-11-21
Publication date: 1998-06-04
Also published as: CA2191511A1; CA2191511C; AU5112498A

Abstract

The cutting assembly functions to sever the urethane bed (24) bonding a windshield (23) to a vehicle. The assembly comprises a reciprocating air gun (2) connected with a cutting blade (4) by a shaft (3). The blade (4) has a straight front cutting edge about 4 inches in width. The blade (4) is reciprocated in and out of the bed to sever it.

Description

CUTTING ASSEMBLY FOR REMOVING WINDSHIELD

FIELD OF THE INVENTION This invention relates to an assembly and method for separating a glass windshield from a vehicle urethane bed by severing the bed along its length.

BACKGROUND OF THE INVENTION In the process of securing a glass windshield to a new car or truck, the manufacturer first extrudes a bead or "bed" of urethane onto the "pinch weld" extending around the perimeter of the window opening. The urethane bed bonds to the pinch weld surface. The glass windshield then is seated on the bed and bonds to it, forming a liquid-tight seal. The urethane bed is hard and tough and not easily penetrated. It commonly has a thickness of about 1/4 inch and width of about 1/3 - 3/4 inches, widening to about 3-1/2 - 4" at the corners. If the windshield is to be replaced, an installer severs the bed along its length, just beneath the inside surface of the glass, leaving the base portion of the bed in place. He then primes the cut surface of the bed, deposits a new bead of urethane on the primed surface and seats the replacement windshield onto the fresh bead to bond it in place. Up to about the end of the 1980's installers used a manually operated knife to sever the urethane bed. The knife was generally L-shaped, having a narrow sharpened blade and a shank or handle equipped with hand grips. The installer would first work the point of the blade inwardly to penetrate the bed and would then reciprocate the blade with short in and out strokes while pulling the blade sideways to saw through the urethane bed along its length. Commencing about 1990, two types of powered tools were introduced commercially, to replace the manually operated tools. These powered tools mimicked the manually operated knife in several structural and operational respects. The first type of tool involved an L-shaped blade and shank powered by an electric motor. The blade was oscillated from side to side. The blade was pointed at its end and narrow (about 1/2 inch wide), to facilitate initial manual penetration. The side edge of the blade was sharpened, so that a lateral cutting action was produced. The second type of tool involved reciprocating a blade which would extend in and out of a sleeve. The blade was actuated by an electric motor. Again, the blade was pointed and narrow (about 1/2 inch width), to facilitate initial penetration. The "throw" or distance advanced by the blade was short, about 1/2 inch.

In use, these tools were characterized by several problems. More particularly: • Cutting with them was slow. The depth and width of the cut were small, requiring a great many cuts to complete the job. Typically it would take about 15 - 20 minutes to cut the windshield free; • Using the prior art assemblies was laborious. The installer would have to apply a sideways pull to these tools, particularly when cutting along the horizontal legs of the bed; • It was common to crack the glass when first penetrating the bed. This could leave broken glass on the dash and elsewhere, which was undesirable; • The cuts made by the tools were shallow. One could only cut into the bed with these tools about 1/2 inch at a time. This meant that at the corners, where the bed width was greatest, it would take prolonged cutting to complete severing the bed. In practice, the installer would revert to using a hand knife at the corners or would break off the glass at the corners and have to later complete the cut by hand of the corner urethane with its embedded glass. In the course of hand cutting the corners, the installer would commonly press hard with his head against the windshield to assist his cutting - this was known to lead to neck injuries; • The cut surface produced by the blades of these powered tools was irregular Gagged and undulating). This was undesirable as the newly extruded bead would in part reproduce this underlying irregularity and the new windshield would then not seat flush against the bed surface. This could lead to a poor seal and subsequent leaking; • The electric motor-driven tools of the prior art were generally bulky and difficult to work with in confined space, such as the apex between the vehicle dashboard and the inside surface of the windshield; • The prior art blades were fragile and expensive - breakage was a problem; and - It was necessary to use soapy water as a coolant and lubricant for the narrow, rapidly moving blades. After the cut was complete, the cut surface needed to be carefully washed to remove soap, as it was detrimental to getting a good bond when new urethane was laid on.

SUMMARY OF THE INVENTION The preferred form of the invention involves combining the following features: • using a reciprocating air gun which delivers a high impact blow with a stroke length of about 1/2 inch; • matching the air gun with a wide, flat blade having a transverse, straight front cutting edge which is at least 2 inches wide and preferably is about 4 inches wide. The blade should be stiff but have sufficient lateral flexibility so as to conform to the curvature of the windshield when manually pressed thereagainst - preferably the blade can be about 4 inches in length and formed of about .05 inch thick stainless steel; and • connecting the blade with the gun with a slender, elongate, substantially rigid shaft which will transmit the impact yet can extend into the narrow apex space between the dashboard and the windshield while spacing the gun well away from this confined area. It has been found that this combination provides a cutting assembly having the following attributes: • The air gun is capable of driving the wide blade into the tough urethane bed to make a clean incision without damage to the bed; • The cutting stroke and blade are sufficiently long to enable the blade to cut through even the wide corners of the bed - this can typically be accomplished in 4 or 5 strokes; • No side pull is required - the blade cuts with an in and out stroke. The installer need only support and guide the device and does not need to press with his head against the inner surface of the windshield; • Surprisingly, the cut surface of the bed is found to be smooth and free of irregularities; • Blade breakage is reduced; and • The removal of a windshield is accomplished in about 3 minutes as compared to the 15 - 20 minutes required for the prior art assemblies. In one broad aspect, the invention involves a cutting assembly comprising: a reciprocating air gun; and a tool connected with the air gun for reciprocation thereby; said tool comprising a shaft, having inner and outer ends and being connected at its inner end with the gun for reciprocation thereby.and a flat blade mounted to the shaft's outer end, said blade having a sharp transverse front cutting edge having a width of at least 2 inches and sufficient lateral flexibility to substantially conform with the curvature of the windshield when pressed thereagainst in use. In another broad aspect, the invention involves a method for separating a glass windshield from a vehicle urethane bed, comprising: providing a reciprocating air gun having a cutting tool mounted thereto for reciprocation thereby, said cutting tool comprising a shaft connected at one end with the gun and at the other end with a flat blade having a front cutting edge of at least 2 inches width; reciprocating the blade longitudinally, into and out of the bed, and severing the bed across its width; and progressively moving the blade along the length of the bed to sever it completely and leave a smooth cut surface. DESCRIPTION OF THE DRAWING Figure 1 is an isometric view showing the cutting assembly; Figure 2 is a top plan elevation of the assembly of Figure 1 ; Figure 3 is a side elevation, partly in section, showing the assembly of Figure 1 ; and Figure 4 is a schematic side view showing the cutting assembly in use.

DESCRIPTION OF THE PREFERRED EMBODIMENT The cutting assembly 1 comprises a reciprocating air gun 2, shaft 3 and blade 4. The air gun 2 is commercially available. An Ingersoll Rand Pneumatic model #117 or a Chicago Pneumatic model # CP715 gun is suitable. The shaft 3 is a 3/4 inch diameter steel rod having an inner end 5 conventionally shaped to connect with the air gun 2. At its outer end 6, a slot 7 extends inwardly to receive the shank 8 of the blade 4. The upper surface of the rod end 6 forms a recess 9. The rod end 6 further forms bolt holes 10 extending transversely therethrough. Nuts 11 and bolts 12 are received in the recess 9 and holes 10 to secure the blade shank 8 to the rod end 6. The blade 4 is formed of stainless steel, has a width at the front edge 20 of about 4 inches, a length of 6 inches and a thickness of .05 inches. While it is substantially rigid, it has sufficient flexibility so that it will conform to the windshield curvature when pressed thereagainst. The blade 4 includes a 2 inch long shank 8 which is received in the rod slot 7. The front edge 20 is straight and sharpened. When assembled and operated, the blade 4 reciprocates with a throw or travel of about 1/2 inch. The blade is pressed against the inside surface 22 of the glass windshield 23 and is driven into the urethane bed 24. It severs the bed just beneath the glass. The installer moves the assembly along the length of the bed by withdrawing the blade from the urethane, moving it to the next adjacent cut position and then again driving the blade in.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A cutting tool, to be used with a reciprocating air gun, for separating a glass windshield from a vehicle urethane bed, comprising: a shaft having inner and outer ends, said shaft being connectable at its inner end to the air gun for reciprocation thereby; and a flat blade mountable to the outer end of the shaft, said blade having a sharp transverse front cutting edge having a width of at least 2 inches and sufficient lateral flexibility to substantially conform with the curvature of the windshield when pressed thereagainst in use.

2. A cutting assembly for separating a glass windshield from a vehicle urethane bed, comprising: a reciprocating air gun; and a tool connected with the air gun for reciprocation thereby; said tool comprising a shaft, having inner and outer ends and being connected at its inner end with the gun for reciprocation thereby.and a flat blade mounted to the shaft's outer end, said blade having a sharp transverse front cutting edge having a width of at least 2 inches and sufficient lateral flexibility to substantially conform with the curvature of the windshield when pressed thereagainst in use.

3. The tool as set forth in claim 1 wherein the blade cutting edge is straight and has a width of about 4 inches.

4. The assembly as set forth in claim 2 wherein the blade cutting edge is straight and has a width of about 4 inches.

5. The tool as set forth in claims 3 or 4 wherein the blade has a length of about 4 inches.

6. A method for separating a glass windshield from a vehicle urethane bed, comprising: providing a reciprocating air gun having a cutting tool mounted thereto for reciprocation thereby, said cutting tool comprising a shaft connected at one end with the gun and at the other end with a flat blade having a front cutting edge of at least 2 inches width; reciprocating the blade longitudinally, into and out of the bed, and severing the bed across its width; and progressively moving the blade along the length of the bed to sever it completely and leave a smooth cut surface.

7. The method as set forth in claim 6 comprising: using water without lubricant as a cooling agent for the blade in use.

8. The method as set forth in claims 6 or 7 wherein: the blade has a width and length of about 4 inches; and the blade is reciprocated with a travel of about 1/2 inch.