US3455367A

US3455367A - Screen assembly

Info

Publication number: US3455367A
Application number: US646013A
Authority: US
Inventors: Frank M Le Tarte
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-06-14
Filing date: 1967-06-14
Publication date: 1969-07-15
Anticipated expiration: 1986-07-15

Description

July 15, 1969 F. M. LE TARTE 3,455,367

' SCREEN ASSEMBLY Filed June 14, 1967 2 Sheets-Sheet l INVENTOR. .FPANK M. 1172mm:

F. M. LE TARTE SCREEN ASSEMBLY July 15, 1969 2 Sheets-Sheet 2 Filed June 14, 1967 m 6G R. ME O SON M M ,3 A E s w W4 5 M L 7 H F W Um o A 0 0 d W M Y u B 0 L 0 United States Patent 3,455,367 SCREEN ASSEMBLY Frank M. Le Tarte, P.0. Box 68, Smith Creek, Mich. 48074 Filed June 14, 1967, Ser. No. 646,013 Int. Cl. A47g /00; A47h 13/00 US. Cl. 160371 6 Claims ABSTRACT OF THE DISCLOSURE BRIEF DESCRIPTION OF THE INVENTION Briefly, a precut section of screening material of the approximate size of a screen frame ismounted in a screen frame by tucking the edges of the screen material into a recess or channel of the metal frame member, thus eliminating the labor involved in trimming and/or dressing the screen material to a specific size. The term approximate size refers to a screen material having dimensions of the order of i625 inches relative to a predetermined line at or near the centerline of the frame member. The next steps are to melt a portion of the thermoplastic strip and press the screen into softened plastic. U

It is an object of this invention to provide an inexpensive frame construction that increases the structural rigidity of the thermoplastic-metal extrusion combination.

Another object of this invention is provision of a method for mounting a precut section of screen on the frame which is more economical and simpler than methods known in the art because it eliminates the step BRIEF DESCRIPTION OF THE DILAWINGS FIGURE 1 is a perspective view of a completed screen assembly made in accordance with this invention;

FIGURE 2 is a cross-sectional 'view, to a greatly enlarged scale, of the thermoplastic strip of FIGURE l;

FIGURE 3 is a cross-sectional view, to a greatly enlarged scale, taken along the line 33 of FIGURE 1, of the U-shaped extruded metal frame strip with the dashed line indicating the position of the thermoplastic strip in the complete frame assembly;

FIGURE 4 is a view of the assembled screen showing the frame, plastic strip, screening material and assembling tool;

FIGURE 5A is a cross-sectional view of the metal frame and showing the position of the tool in fabricating the completed screen assembly with a cutaway view of the roller showing a Teflon or similar material coated on the metal roller;

FIGURE 5B is a fragmentary side view of FIGURE 5A looking in the direction of arrow 5B; and

FIGURE 6 is a cross-sectional view of the completed frame assembly, to an enlarged scale, taken along the the arrows.

2 DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing, a screen 10 is secured to a rigid metal frame 11 by means of an elongated thermoplastic strip 12.. Frame 10 may be formed from a notched single piece metal extrusion as disclosed in my patent No. 3,097,684. The complete assembly is shown in perspective in FIGURE 1. The structural details, the manner of assembly of the plastic and metal-strips, and the mounting of the frame aredescribed in conjunction with FIGURES 2 through 6. FIGURES 2 and 3 are views in section, to a greatly enlarged scale, of the plastic strip 12 and frame 11, which is advantageously: formed from a generally U-shaped metal extrusion.

Frame 11 and strip 12 are each cut to a predetermined length. The frame 11 is preferably formed by notching the elongated metal with four notches toeleave' one uncut extrusion wall at each notch. Corners are formed by bending each uncut wall of the extrusion at each notch and joining the ends of the extrusion by means-of a gusset 13. The corner may be strengthened by welding the abutting edges of each notch. The gusset is preferably secured to the extrusion 11 by means of spot welding, as I each length of frame section. The plastic strip issnapped' into place in the channel of the frame 11 in a manner shown in dotted outline in FIGURE 3. Alternatively, a single length of plastic equal to the perimeter of frame 11 may be snapped into the metal channel member before the channel member is notched. The stripwill then be mitered in four segments. The mitered ends will abut each other when the frame is bent at the notches.

Strip 12 is preferably formed of any convenient thermoplastic material, such as Cycloac, which is sold by Marbon Chemical Div. This material is a styrene-type, rigid, thermoplastic resin which softens gradually as the temperature is increased beyond 185 F. The-particular strip 12 includes a main body portion 15 from which three longitudinal ridges 16 pr0ject.-A longitudinal tongue or lip 18 projects from the main body portion 15 at an angle of relative to ridges 16 and secures one edge of strip 12 in frame 11, as will be subsequently described.

The plastic strip 12 also includes, as viewed in section in FIGURE 2, a leg 23 depending from the main body portion 15 and having three

portions

24, 25 and 26. These portions are integrally formed with each other and with main body portion 15.

Portions

24, 25 and 26 preferably define a series of right angles. Leg 23 terminates in a foot 28, and leg 23 has sufficient resilience so that the foot 28 can snap into a slot in the metal extrusion to lock the strip in the metal frame in a manner to be described.

Frame 11 is preferably formed from a soft metal extrusion 20, such as aluminum. Extrusion 20 includes a base portion 29 and a pair of

arms

30, 31 extending substantially perpendicularly from base 29.

Arms

30 and 31 define the inner and outer walls, respectively, of the frame. A ledge or lip 32 projects toward the outer wall 31 from the end of inner wall 30. A relatively wide lip 34 projects perpendicularly from wall 31'toward wall 30. A tongue or shelf 35 projects perpendicularly from the inside wall 31. Shelf 35 supports plastic strip 12 in a manner shown in phantom outline in FIGURE 3 and shown in full lines in FIGURES 4, 5 and 6. In assembling the plastic strip on shelf 35, the plastic strip is first moved in the channel of member 20 in the direction of arrow 36. After leg 23 passes shelf 35, the plastic strip is moved in the direction of arrow 37 until lip 18 engages the inner surface of wall 30 and the inner surface of ledge 32 and until the foot 28 snaps into a longitudinal groove 40. Member 20 also includes a pair of opposed ridges 38, 39 Ridge 39 projects perpendicularly from base 29 toward top ledge 34. Ridges 38 and 39 and wall 31 define a substantially enclosed rectangular channel to receive gusset 13.

The engagement of foot 28 in a groove 40 in base portion 29 prevents movement of the thermoplastic strip 12 in the plane of the base 29 in a direction opposite to arrow 37. The motion of strip 12 in a direction opposite to arrow 36 (as might be otherwise produced by pressure upon screen 10 in a direction upward, as viewed in FIGURES 3 and 6) is prevented by the engagement of tongue 18 with the inside surface of ledge or lip 32 and the engagement of leg 25 with the lower surface of shelf 35.

After the plastic strip 12 is mounted in the frame 11, a precut area of screen 10 is placed upon the frame and strip with the edges of the screen overlapping the plastic strip in a manner shown in FIGURE 4. Screen 10 may be of conventional metal such as aluminum or it may be formed of suitable thermoplastic material. Roller 41 may be heated, as will be subsequently described, or heat sufficient to soften strip 12 and screen 10 may be provided in the form of a hot gaseous blast from a suitable nozzle 42. The overlapping edges of the screen are tucked into the channel of the frame member 20, as shown in FIG- URES 3 and 6. The longitudinal ridges 16 are subsequently melted and the screen is pressed into the softened plastic material by means of a single tool, such as the roller 41. By using precut screen sections, a substantial savings (approximately 25%) is obtained in the purchase price of screen, when screen is sold in rolls, and a portion of the roll is damaged during production or handling. The roll cannot be sold hence an appreciable loss occurs. However, if screen is purchased in precut, fiat sections, only the damaged sections need be returned. Further, fiat sections may be palletized to facilitate handling without damage.

Roller 41 is rotatably mounted on a suitable bifurcated handle 44 by an axel 45, journaled in the bifurcated portion bf the handle 44. The roller 41 is preferably electrically heated by passing an electrical current through a resistive material 48 beneath the Teflon coating 49 of the roller 41.

Contacts

46 and 47, appearing on the lefthand fork of the bifurcated handle 44, as viewed in FIGURE 4, provide a means for conducting electrical current to the resistive coating on roller 41. Resistive coating 48, shown in FIGURE 5, is preferably covered by a,Tefion or other suitable coating 49, which Teflon coating prevents the heat softened plastic material of the plastic strip 12 and/or screen 10 from adhering to the roller 41.

FIGURES A and 5B show the melting and fusing of the longitudinal ridges 16 into the screen 10. As best shown in FIGURES 5A and 5B, the roller 41 rests upon the outer top ledge or rail 34, which rail projects above the inner rail 32 to act as a gauge to limit the amount of pressure and the depth of penetration of the roller 41 into the longitudinal ridges 16. After the roller 41 is passed along two adjoining sides of the frame 11, a suitable tool, not shown, preferably having the saw-tooth end, is inserted into the screen adjacent the channel at the corner diagonally opposite the corner connecting the two portions of the strip 12 to which the screen has been fastened. By applying pressure at this diagonally opposite corner, any sag is removed from the screen and the heated roller or roller and hot gas tube 42 may be passed along the two remaining sides of the plastic strip 12 to thus complete the mounting of the screen on the plastic strip 12.

The structural details of the resulting junction of the screen and plastic strip are best shown in FIGURE 6 which is similar to FIGURE 5A except that the roller 41 has been removed. The pre-cut screen 10 has been bonded to the longitudinal ridges 16 of the strip 12, as best seen in FIGURE 6.

Typical dimensions for the channel member 20, expressed in inches, are as follows:

Wall 30 0.245 Base 29 0.750 Wall 31 0.275 Inner ledge 32 0.093 Outer ledge 34 0.312

The width of shelf 35, measured from the outside of wall 30, is 0.280 while the height of the gusset channel, formed by the opposed

arms

30, 31, is 0.185. The groove 40 is of the order of 0.040 in Width and 0.015 in depth. Strip 12 may be relatively rigid, such as being within the range of 65 to on the D scale, as measured on a Shore Durometer. Typical dimensions for a strip 12, in inches, are:

Width of body 15 .225 Height of body 15 .070 Overall height .250 Overall width .270 Width of ridges 16 .045 Width of tongue 18 .045

In summary, structural rigidity is accomplished by means of a design which prohibits motion of the thermoplastic in any direction in which a tension on the screening material could force it to move, while increasing the economy of construction by eliminating the necessity for trimming the screening material. In particular, a novel feature includes the engagement of foot 28 with groove 40 for prohibiting movement of the thermoplastic away from sidewall 30 of the U shaped extrusion 20 without increasing the complexity of the construction. Also, the engagement of tongue 18 under shelf 32 prevents strip 12 from being pulled out when pressure is applied to the screen 10 upwardly, as viewed in FIGURES 3 and 6.

In accordance with the patent statutes, the principles of the present invention may be utilized in various ways, numerous modifications and alterations being contemplated, substitution of parts and changes in construction being resorted to as desired, it being understood that the embodiment shown in the drawing is given merely for purposes of explanation and illustration without intending to limit the scope of the claims to the specific details disclosed. For example, the step of heating the plastic strip and the plastic screen may be performed by dielectric high frequency heating. In this manner, the roller acts as one electrode and the screen frame acts as the other electrode when a high frequency signal is applied to these electrodes.

I claim:

1. A screen assembly comprising:

a polygonal frame formed of a substantially U shaped channel member having in cross-section a base portion,

a pair of arms extending from said base portion and a longitudinal shelf extending from one arm toward the other arm,

an elongated thremoplastic strip having a longitudinal slot therein said strip being mounted in said channel with said shelf extending into said slot, and

a screen member, said thermoplastic strip being fused around said screen member.

2. A screen assembly according to claim 1 wherein said channel member includes means for retaining said strip on said shelf.

3. A screen assembly according to claim 1 wherein said shelf extends from the inner wall of said frame toward the outer wall of said frame and wherein said channel member includes means for preventing movement of said strip transversely relative to said shelf.

4. A screen assembly according to claim 3 wherein said channel member has a longitudinal ledge projecting from the end of one arm toward the other arm and wherein the edge of said screen projects into said channel member and beneath said ledge, said one arm being longer References Cited stag; said other arm to act as gauge for said thermoplastic UNITED STATES PATENTS 5. A screen assembly according to claim 1 wherein 1,794,956 3/1931 Heath 160 "395 said frame includes a lip projecting from one of said 5 2,126,544 8/1938 Everhal'd 160 395X arms toward the other of said arms and wherein said 2,325,500 7/1943 FosPerg 16O 383 plastic strip includes a longitudinally extending tongue 2,335,361 11/1943 Schlner 16O395 portion extending beneath said lip whereby said lip pre- 2,783,834 3/1957 Brame 160 395 vents said screen from pulling said strip from said shelf 3,097,684 7/1963 Le Tarte 160381 X when pressure is applied to said screen. 3,214,314 10/1965 ROW Bottam 160 371 X 6. A screen assembly according to claim 5 10 3,273,633 9/1966 Seidmon et wherein said tongue portion is positioned between said shelf and said lip and REINALDO P. MACHADO, Primary Examiner wherein said channel member includes a locking groove P. C. KANNAN, Assistant Examiner facing said shelf and opposed thereto, said strip in- 15 eluding a portion projecting into said groove to retain US. Cl- X.R.

said strip on said shelf. 160383, 395