NZ242872A - Plastics friction pivot joint for window stay - Google Patents

Description

242872 js- >• :■ O \2imwS J ... , * ' PATENTS FORM 5 Number 242872 PATENTS ACT 1953 Dated May 22, 1992 COMPLETE SPECIFICATION A FRICTION PIVOT JOINT I, RONALD PERCIVAL DAVIS, a New Zealand citizen, of 77 Breaker Bay Road, Seatoun, Wellington, New Zealand do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement 242872 TECHNICAL FIELD My present invention comprises a window stay friction pivot joint.

BACKGROUND ART A friction window stay consists of a frame plate, a sash plate, and arms between the frame plate and sash plate. The arms are connected to the frame plate and the sash plate by friction pivot joints, which provide the friction of the stay. Two window stays are used to mount each window sash, either at each side of the sash in an awning hung sash or at top and bottom in a casement hung sash. The frame plate is fixed to the frame of the window, typically by screws, and the sash plate to the sash of the window. The plates and arms of a window stay are conventionally formed of metal such as aluminium or stainless steel, because of the loads which the stay must bear.

A large number of types of friction pivot joint for use between the arms and plates of a window stay are known. European patent 86305014.2/US patent 4,721,406 disclose one form of friction pivot joint known as the button bearing which has been commercially successful. Like most window stay friction pivot joints, this form of joint connects a frame or sash plate and arms of a window stay which are formed of metal and a bushing of nylon or similar is 242872 interposed between the metal frame or sash plate and the arm to prevent metal to metal contact in the joint between moving parts.

DISCLOSURE The present invention alternative form of window stay OF INVENTION provides an improved or at least friction pivot joint.

In broad terms the invention may be stated to comprise a friction pivot joint between an injection moulded plastics frame plate or sash plate of a window stay and an arm of the window stay, comprising an integral annular shoulder projecting from the plastic frame plate or sash plate, an aperture in the arm whereby the arm is located over the plastic shoulder with the plastic shoulder projecting through the arm and the exterior of the annular plastic shoulder forming a bearing surface for pivotal movement of the arm about the shoulder, and a fastener fixing the joint and applying friction creating pressure thereto comprising a shank portion extending through the interior of the annular plastic shoulder and fixed into the plastic material thereof or of a co-axial aperture in the plastic frame or sash plate beneath the shoulder, with plastic material integral with the annular shoulder extending from the shoulder and over the arm about the end of the shoulder, between the arm and a head of the fastener to prevent direct contact therebetween. 242872 Preferably the shank of the fastener is threaded and the fastener is screwed, preferably with a self-tapping thread, into the plastics material of the interior of the shoulder or the coaxial aperture beneath the shoulder.

The invention also comprises a method of forming a friction pivot joint between a frame plate or sash plate of a window stay and an arm of the stay, comprising injection moulding the frame plate or sash plate from a plastics material with an integral annular shoulder projecting from the frame or sash plate, locating the arm over the plastic shoulder with the plastic shoulder projecting through the arm and the exterior of the annular plastic shoulder forming a bearing surface for pivotal movement of the arm about the shoulder and a top part of the shoulder extending beyond the arm, and inserting a fastener to fix the joint and fixing the fastener into the plastic material within the interior of the shoulder or of a co-axial aperture in the frame or sash plate below the shoulder and during inserting and fixing of the shoulder causing the top part of the plastic shoulder beyond the arm to be bent to lie over the arm between the arm and a head of the fastener to prevent direct contact therebetween.

BRIEF DESCRIPTION OF DRAWINGS Preferred forms of the window stay friction pivot joint are illustrated, by way of example, in the accompanying drawings, wherein: 242872 Fig. 1 is a cross-sectional view of a first preferred form of friction pivot joint of the invention between a frame plate and an arm of a window stay (only the end of the frame plate is shown), also showing a mounting screw as would be used in practice for mounting the stay to a window frame, Fig. 2 is a view from above of the first preferred form joint (with no mounting screw shown), Fig. 3 is a cross-sectional view through the end of the frame plate of the first preferred form joint with all other components absent, before forming the joint, Fig. 4 is a view from above of the end of the frame plate shown in Fig. 3, in the direction of arrow A in Fig. 3, Fig. 5 is a cross-sectional view through a preferred form fastener forming fixing means of the joint, Fig. 6 is a view from above of the preferred form fastener, Fig. 7 is a cross-sectional view of a second preferred form of friction pivot joint of the invention between a frame plate and an arm of a window stay similar to Fig. 1 of the first • 242872 preferred form joint, but not showing the mounting screw shown in Fig. 1, Fig. 8 is a view from above of the second preferred form joint similar to Fig. 2, Fig. 9 is a cross-sectional view through the end of the frame plate of the second preferred form joint with all other components absent, before forming the joint, similar to Fig. 3, and Fig. 10 is a view from above of the end of the frame plate shown in Fig. 9, in the direction of arrow B in Fig. 9, similar to Fig. 4.

DESCRIPTION OF PREFERRED FORMS In the first preferred form of friction pivot joint shown in Figs 1 to 4 the injection moulded plastic frame (or sash) plate is indicated at 1. An arm is indicated at 2. An integral plastic annular shoulder 3 surrounds and projects from the periphery of an aperture 4 through the plastic frame plate 1 as shown. Fig. 3 shows the shoulder 3 integrally formed on the frame plate 1 before forming of the joint. In the first preferred form shown in Figs 1 to 4 an annular base 5 to the joint is preferably moulded as shown so that the end of the fastener 6 will not be exposed.

The arm 2 has an aperture whereby the arm 1 is located over the plastic shoulder 3 with the shoulder projecting through the arm so that the exterior of the annular plastic shoulder forms a bearing surface for pivotal movement of the arm. A fastener 6 having a shank and a head extends through the interior of the plastic shoulder 3 and is fixed into the plastic material of the interior of the shoulder and/or in the co-axial aperture through the plate 1 below. The fastener 6 fixes the joint and applies friction creating pressure. The fastener 6 has self-tapping threads and is screw threaded into the interior of the shoulder 3, so that it forms its own thread and bites into the plastic wall.

Using a self-tapping thread is preferred but alternatively a thread may be moulded in the interior wall of the shoulder 3 and/or aperture below.

The fastener 6 may be fixed by other than screw threading, but screw threading is preferred because it enables the friction level to be adjusted during the life of the stay. For example, barbs on the shank of the fastener may bite into the plastic of the interior wall of the shoulder or aperture below to fix the fastener.

As the fastener 6 is inserted and screwed home, the top part 3a (see Fig. 3) of the shoulder 3 is bent over the arm to become interposed between the underside of the head of the fastener 6 and the arm 1 as shown in Fig. 1. This integral material of the shoulder acts as a bushing between the top of the arm and the head of the fastener 6. Figs 1 and 2 show the completed joint, and Figs 3 and 4 show the injection moulded plate component in cross-section and from above before assembly with the arm and button, and the top part 3a of the shoulder preferably has a reduced wall thickness relative to the main body 3b of the shoulder as shown in Fig. 3.

The preferred form fastener 6 is shown in Figs 5 and 6. It comprises a flange-like head portion 6a and a cylindrical shank portion 6b which is screw threaded as shown. The fastener preferably has a hollow interior so that a fixing screw for the stay may be screwed through the joint as shown in Fig. 1. The fastener may have a hex interior to enable screwing home of the fastener with a hex key during manufacture, and friction adjustment after installation.

The second preferred form of friction pivot joint shown in Figs 7 to 10 is similar to that of Figs 1 to 4 except that the frame or sash plate has a dish-shaped annular recess about the shoulder and the arm has a complementary annular depression which engages into the annular recess. In Figs 7 to 10 the same reference numerals as in Figs. 1 to 4 indicate the frame or sash plate 1, arm 2, shoulder 3, aperture 4, and fastener 6. The same fastener as shown in Figs 5 and 6 may be used. Referring to Figs 9 and 10, the shoulder comprises a top part 3a of reduced wall 242872 thickness which is bent over as the fastener 6 is screwed home during forming of the joint and main body 3b of the shoulder. The dish-shaped annular recess 7 surrounds the shoulder 3, as best seen in Figs 9 and 10. The shoulder 3 projects from the bottom of the recess. The arm 2 has a depression 2a which is of a complementary shape to the dish-shaped recess 7 in the frame or sash plate. The aperture through the arm is formed through the depression 2a in the arm. In the completed joint, the depression 2a of the arm engages into the complementary annular recess 7 in the frame or sash plate, as shown in Fig. 7. This further assists in securely locating the arm and provides another friction creating surface. Also, the surrounding part of the arm may make direct contact with the top of the plastic frame or sash plate, providing further support for the arm, particularly where the plate is a frame plate in a casement window situation.

The joint of the invention can be formed with less components than conventional friction pivot joints. Window stays incorporating the joint can be produced more economically. Another advantage of the preferred from pivot joints is that because they include a central aperture the joints in the frame and sash mounting plates can be 'screwed through' with mounting screws,' as well as the mounting holes. The stay is then secured to the frame and sash of the window at the same point that loads are applied by the stay arms, particularly in casement applications, so that distortion of the frame and sash mounting plates is minimised. 242872 The foregoing describes my invention including a preferred form thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof, as defined in the claims.

Claims (9)

242872 WHAT I CLAIM IS:

1. A friction pivot joint between an injection moulded plastics frame plate or sash plate of a window stay and an arm of the window stay, comprising an integral annular shoulder projecting from the plastics frame plate or sash plate, an aperture in the arm whereby the arm is located over the annular plastics shoulder with the annular plastics shoulder projecting through the arm and the exterior of the annular plastics shoulder forming a bearing surface for pivotal movement of the arm about the annular plastics shoulder, and a fastener fixing the joint and applying friction creating pressure thereto comprising a shank portion extending through the interior of the annular plastics shoulder and fixed into the plastics material thereof or fixed into the plastics material of a co-axial aperture in the plastics frame or sash plate beneath the annular plastics shoulder, with plastic material integral with the annular plastics shoulder extending from the annular plastics shoulder and over the arm about the end of the annular plastics shoulder, between the arm and a head of the fastener to prevent direct contact therebetween.

2. A friction pivot joint as claimed in claim 1, wherein the shank of the fastener is threaded and the fastener is screwed into the plastics material of the interior of the annular plastics shoulder or the co-axial aperture beneath the annular plastics shoulder. - 11 - » - /•.- A rv. •114 '7/

3. A friction pivot joint as claimed in claim 2, wherein the fastener is screwed into the plastics material of the interior of the annular plastics shoulder or the co-axial aperture beneath the annular plastics shoulder with a self-tapping thread into the plastic material.

4. A friction pivot joint as claimed in any one of claims 1 to 3, wherein the annular plastics shoulder prior to locating of the arm about the annular plastics shoulder and insertion of the fastener comprises a first annular part projecting from the frame or sash plate of greater wall thickness and a second annular part above the first part of reduced wall thickness, the second part having been bent over to lie between the head of the fastener and the arm (during insertion of the fastener) to prevent direct contact therebetween.

5. A friction pivot joint as claimed in any one of the preceding claims, wherein the fastener has a hollow interior axially through the head and shank portion of the fastener.

6. A friction pivot joint as claimed in any one of the preceding claims, wherein the frame or sash plate comprises a dish shaped annular recess surrounding the annular plastics shoulder and the annular plastics shoulder projects from the bottom of said dish shaped annular recess, and wherein the aperture in the arm is 242872 formed in a complementary annular depression from the arm engaging into the annular recess about the annular plastics shoulder.

7. A method of forming a friction pivot joint between a frame plate or sash plate of a window stay and an arm of the stay, comprising injection moulding the frame plate or sash plate from a plastics material with an integral annular shoulder projecting from the frame or sash plate, locating the arm over the annular plastics shoulder with the annular plastics shoulder projecting through the arm and the exterior of the annular plastics shoulder forming a bearing surface for pivotal movement of the arm about the annular plastics shoulder and a top part of the annular plastics shoulder extending beyond the arm, and inserting a fastener to fix the joint and fixing the fastener into the plastic material within the interior of the annular plastics shoulder or into the plastics material of a co-axial aperture in the frame or sash plate below the annular plastics shoulder and during inserting and fixing of the fastener causing the top part of the annular plastics shoulder beyond the arm to be bent to lie over the arm between the arm and a head of the fastener to prevent direct contact therebetween.

8. A method as claimed in 7, including fixing the fastener by screwing into the plastics material of the interior of the annular plastics shoulder or of the co-axial aperture beneath the annular plastics shoulder. - 13 -

9. A method as claimed in claim 7, including fixing the fastener by screwing into the plastics material of the interior of the annular plastics shoulder or the co-axial aperture beneath the annular plastics shoulder with a self-tapping thread. WEST-WALKER McCABE per: ATTORNEYS FOR THE APPLICANT