JPS645932B2 - - Google Patents

Description

Claim 1: A closure member having a flat surface including a strip around the entire periphery; a screen covering the closure member such that an edge is close to the strip; A continuous weld bead made of the same material as the screen whose edge is adhered to the strip.

2. the screen has a side facing the closure, the edge surrounds the side, and the screen is flat, and the weld bead extends to the edge of the screen without connecting the side of the screen to the closure. 2. A filter leaf according to claim 1, wherein the edge is adhered to the strip.

3. The closure member comprises a closure frame having an inner periphery forming a space therein, an outer periphery, and a flat side surface extending between these peripheries, and the screen has an outer periphery that is connected to the frame. The filter leaf according to claim 1, which covers the open space so as to overlap and adjoin the sides of the filter leaf.

4. Claim 3, wherein the frame is annular, and the edges of the weld bead and screen are circular.
The filter leaf described in section.

5. The closure member includes a flat circular plate, the strip includes an annular surface on the plate, and the filter leaf connects the screen and the closure member to space the screen from the closure member in an area bounded by the edge of the screen. The filter leaf according to claim 1, comprising a plurality of ribs arranged between the filter leaves.

6. The closure member consists of a pan (pot-shaped body) having a flat bottom surrounded by an upwardly projecting peripheral wall;
2. A filter leaf according to claim 1, wherein the peripheral wall has an edge surface forming a band and the screen is flat.

7. The filter leaf according to claim 1, wherein the screen and closing member are made of stainless steel.

8. A filter leaf according to claim 1, having a liquid outlet formed in the closure member.

9. A filter leaf according to claim 1, wherein the weld bead has a flange projecting from the edge of the screen toward the center of the closure member.

10. The screen is a three-layer diffusion bonded thin layer consisting of an outer layer of a fine-mesh screen, an intermediate layer of a coarse-mesh screen, and an inner layer of a perforated plate that is more rigid than these screens. filter leaves.

11. The filter leaf according to claim 10, wherein the intermediate screen and perforated plate are entirely contained within a frame.

12. The filter leaf of claim 1, wherein the weld bead has a continuous flange projecting toward the center of the screen and into the closure member.

13. The filter leaf of claim 12, wherein the flange projects into the closure member at an angle of about 30 degrees to about 50 degrees relative to the flat surface.

14. Claim 13, wherein said angle is approximately 40°.
The filter leaf described in section.

15. A method for manufacturing a filter leaf having a screen welded around the entire circumference to a continuous, elongated closure member having a main plane, the screen covering one side of the closure member and forming part of the closure member. clamping the closure member and the screen together such that a portion of the screen overlaps; and clamping the overlapping portion of the closure member and the screen together with a welding beam selected from the group consisting of an electron beam and a laser beam; irradiation, melting and fusing them together in a weld bead, and clamping the closure member and screen together while directing the area around the area where the closure member and screen overlap to the beam. A method of manufacturing comprising: moving the screen to form a continuous weld of the screen to the closure member around the entire circumference of the screen.

16. The manufacture of claim 15, wherein all steps are performed to weld the first screen around its periphery to one side of the closure member, and then all steps are repeated to weld the second screen to the other side of the closure member. Method.

17. According to claim 15, said melting and fusion produces a continuous, elongated weld bead having an annular portion extending inwardly into the closure member and away from the side of the closure member to which the screen is welded. Production method.

18 The clamping step includes clamping the closure member and the screen, which are circular, together between two plates, and the moving step includes rotating the plates about their centers to separate the closure member and the screen. 16. The method of claim 15, comprising moving the welding beam past the welding beam.

19. The method of claim 15 or 18, including the step of moving the closure member and screen relative to the beam at a speed of at least 20 in/min (0.5 m/min).

20 Said speed is at least 40 in/min (1.0 m/min)
20. The manufacturing method according to claim 19, wherein: min).

21. A method according to claim 15 or 18, wherein the beam is inclined at an angle of 40° from the main plane of the closure member.

22. The method of claim 21, wherein said angle is about 30° to about 50°.

23. After the screen is welded to the closing member, the center of rotation of the plate is moved away from the position where the beam contacts the screen, and then the plate is rotated relative to the beam to polish the outer periphery of the weld. 19. The manufacturing method according to claim 18.

24. Cutting a portion of the overlapping portion of the screen and leaving the remaining portion on one side of the closure member, and the irradiation step then irradiating the remaining overlap portion to weld the screen to the closure member. 19. The manufacturing method according to claim 15 or 18, characterized in that:

25. The manufacturing method according to claim 15 or 18, wherein the irradiation step includes irradiating and cutting the screen along a line spaced from the outer periphery of the screen and simultaneously welding the screen to the closure member.

26 the screen has an inner portion covering the closure member and an outer portion surrounding the inner portion, the inner portion of the screen being welded to the closure member;
26. The method of claim 25, wherein the outer part remains free.

27 If the welding beam is approximately
Claim 2 tilted at an angle of 30° to about 50°
The manufacturing method according to item 6.

28 The screen is an outer layer of a three-layer laminate having a screen as an intermediate layer having a coarser mesh than the outer layer and a perforated plate as an inner layer, and the screen is an outer layer of a three-layer laminate having a screen as an intermediate layer having a coarser mesh than the outer layer, and the intermediate and inner layers of the laminate are cut. 19. A method as claimed in claim 15 or claim 18, including the step of ensuring that these are completely within the closure member.

FIELD OF THE INVENTION The present invention relates to a filter leaf and a method of manufacturing such a filter leaf.

PRIOR ART DISCLOSURE Filtration devices have traditionally been used to filter a wide variety of materials such as water, oil, juice, syrup, and beer beverages. The most effective filters have a closed chamber in which the liquid to be filtered is discharged under pressure and forced to pass through a plurality of parallel filter leaves feeding a common outlet. The interior of each filter leaf communicates through a common outlet, into which the filtrate is discharged.

A typical filter leaf includes a pair of screens secured to one or both sides of a closure ring. The material to be filtered is forced through the screen and into the filter space within the ring and screen.
There are two types of filter leaves: rotating type and stationary type. US Patent No.
No. 3542205 discloses a rotating filter leaf.

For many years the industry has investigated the production of stationary filter leaves with stainless steel screens welded around the periphery on both sides of a stainless steel closure ring. Such attempts were unsuccessful because welding was slow and the temperature of the closure ring rose too high during the welding process, causing it to stretch inappropriately. When the ring shrinks after cooling, the screen welded to it becomes slack. A loose screen will be precoated, but will pop and cause the precoat to crack.

Even with slight slack, the screen "bulges" when subjected to different fluid conditions. For example, if a filter screen is precoated with a thin coating of filtration enhancer, the coating will crack as the screen snaps back into its original position due to the loss of liquid pressure thereon. This occurs during the subsequent filtration step.
Contaminate the filtrate. As the screen becomes looser, it becomes wrinkled, and the repeated cycles between high and low pressure during filtration cause the wrinkled screen to flex back and forth, work harden, and eventually break.

The present invention overcomes the drawbacks of the prior art by manufacturing the filter leaf from a closure member to which a screen is welded, whereby the screen tensions on the closure member and tends to bulge or wrinkle, leading to premature failure. Never. Furthermore, welding is performed ten times faster than prior art welding.

SUMMARY OF THE INVENTION The present invention provides a filter leaf that includes a continuous, elongated closure member having a major plane. A first and a second screen are secured on both sides around the entire circumference of the closure member by a welding process selected from the group consisting of electron beam welding and laser beam welding, with a filtrate extraction between the two screens and the ring. Limit your space. Also provided is a member for removing the filtrate from the extraction space.

The heating for welding is always limited to a small area,
Also, the total temperature change of the closure member is limited in time during welding so that the closure member does not undergo undesirable expansion and contraction. Therefore, the screen adheres tightly to the closure member under tension during welding, and after welding, the screen remains taut and does not wrinkle. Additionally, the method of the invention prevents the release of internal stresses within the closure member, which is sometimes formed by bending. If the closure member is unstressed by excessive heating, it will warp out of its predetermined shape.

In a preferred embodiment, the closure member and screen are made of stainless steel, and the screen is simultaneously cut to size and welded to the closure member by laser welding.

In some embodiments, a separate perforated steel plate underlies each screen and an open screen is disposed between the perforated plate and the filtration screen. Desired embodiments also include a rigid and permeable support between the two perforated steel plates. Preferably, in each group of these elements, the steel plate, the open screen and the outer filtration screen are fixed together by diffusion bonding, and the permeable steel support between the two permeable plates has a ring around it at intervals. Tack welded to the inside of the In a desirable embodiment of the filter leaf,
The welding is carried out such that an annular inwardly extending weld bead is formed in the closure member below the periphery of the screen where the screen is welded to the closure member.

In a method of manufacturing a filter leaf having first and second screens welded on opposite sides of a continuous and elongated closure member, the present invention comprises clamping the closure member between two plates and one of the screens. , the screen covering one side of the closure member such that the closure member and an outer portion of the screen project outwardly from one of the plates. The outwardly projecting portions of the screen and closure member are irradiated and welded together with either a laser beam or an electron beam. The perimeter of the outwardly projecting portion of the closure member and screen is moved relative to the laser beam or electron beam, while the closure member and screen are clamped together to form a continuous weld bead of screen around the entire perimeter of the closure member. .

When manufacturing circular filter leaves, the plate is preferably rotated about the center of the filter leaf, while the beam remains stationary. When using a laser beam, the beam should be rotated from approximately 30° outside the major plane of the filter leaf.
towards the workpiece at an angle of 50°, preferably 40°. After the screen is welded to the circular closure member or ring, the center of rotation of the plate is moved slightly from the point where the beam contacts the workpiece, the plate is rotated through 360°, and the beam is attached to the remaining protruding wire or weld of the screen. ``Flame sand'' other rough areas. Alternatively, the second welding beam may be arranged to act on the workpiece after the first beam has performed the welding operation as described above.

In a preferred method, the screen is initially oversized when clamped between the plates. The perimeter of the screen is then cut so that the perimeter of the screen remains protruding from the perimeter of one of the plates. The outer edge of said periphery is then welded to the closure member.

In the device, the invention includes a bottom plate on which the closure member rests. A presser plate is located above and spaced apart from the bottom plate. A member is provided for actuating the presser plate toward and away from the bottom plate, the lower surface of the presser plate contacts one of the screens on the closure member, and the screen and closure member are moved relative to the two plates. Clamp in a fixed position. A portion of the ring and screen protrudes outward from the holding plate. A high energy welding beam, such as an electron beam or a laser beam, is positioned to impinge on the closure member and the outwardly projecting portions of the screen to melt and weld them together.

Desirably, the weld is close to the inner edge of the closure to minimize the tendency for material to become trapped between the closure and the screen when the filter leaf is used for filtration.

A preferred embodiment of the apparatus also includes a member for flowing an inert gas into the space between the plate and the closure member during the welding operation. A member is also provided for moving the circumference of the plate relative to the beam so as to weld the screen around the entire circumference of the ring. When manufacturing circular filter leaves, the plate is preferably rotated about the center of the filter relative to the welding beam.

In one embodiment of the invention, a clamp ring presses down on the outer edge of the screen while the screen is cut by a beam and welded to the closure member.

In another aspect of the invention, a hold-down member adjacent where the beam impinges on the screen and closure member holds the screen against the ring during welding.

Preferably, after the welding operation is completed, a member is included to move the center of rotation of the plate away from the point of contact with the beam, so that the periphery of the weld screen is "flame polished". In some embodiments, the plate is supported on a frame pivotally mounted to a support, and the plate can be moved toward and away from the location where the welding beam impinges on the workpiece.

In a preferred embodiment of the invention, the bottom plate has an annular step on which the closure member rests, which formally positions the closure member relative to the bottom plate, and which is pre-welded to the bottom side of the ring placed on the bottom plate. Provide space for a screen.

Another aspect of the invention includes a member for cutting the projecting outer portion of the screen prior to welding, leaving a narrow annular periphery projecting outwardly from the backing plate. The periphery is then welded to the closure member.

Said plate is made of a material having a substantially higher thermal conductivity than the screen and closure member. For example, if the screen and closure member are made from stainless steel, the plate may be made from aluminum, copper, silver or other suitable material with relatively high thermal conductivity.

[Brief explanation of drawings]

FIG. 1 is a front view showing a stationary filter leaf manufactured according to the present invention. 2 is a view taken along line 2-2 in FIG. 1, FIG. 3 is a perspective view of an apparatus for manufacturing a circular filter leaf according to the present invention, and FIG. 4 is a partial cutaway of the apparatus shown in FIG. 3. 5 is a plan view of the device shown in FIG. 4, FIG. 6 is a view taken along line 6-6 in FIG. 5, and FIG.
Figures 3 to 5 are enlarged cutaway perspective views showing one end of the frame on which the illustrated device is placed, Figure 8 is an enlarged sectional view of the area indicated by arrow 8 in Figure 4, and Figure 9 is an enlarged sectional view of the area indicated by arrow 8 in Figure 4. 6 taken along line 9--9; FIG. 10 is an enlarged cut-away partial front view showing a device for cutting the screen before welding it to the closure member; FIG. 11 is a view taken in accordance with the invention; FIG. 12 is a longitudinal sectional front view of a bread-shaped filter leaf manufactured according to the present invention. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 1 and 2, a stationary circular filter leaf includes a circular closure ring having an outlet 22 through the lower portion of the periphery of the filter leaf. The outlet of the filter leaf is connected to a conventional header tube 24 for moving filtrate from inside the filter leaf. The major plane of the closure ring defines the major plane of the filter leaf. The diameter of the filter leaves is of some suitable size, for example 48 inches (1.2 m), and the closure ring is rectangular or of any other desired shape in cross section. In a typical 48in (1.2m) circular stationary filter leaf, the cross section of the closure ring would be 1/2in x 1/2in (1.27cm x 1.27cm).

As shown in Figure 2, the first three-layer diffusion adhesive thin layer 2
6 is welded around the entire circumference of the upper side of the closure ring 20 (in FIG. 2). 2nd three-layer diffusion adhesive thin layer 2
8 is welded around the entire circumference of the lower side of the closure ring (in FIG. 2). Circular slit between two thin layers
A single circular piece of screen or coarse mesh screen (e.g. 1 mesh screen) 3
0 is secured around its periphery to the inner surface of the closure ring by welds 31 at approximately 45° intervals on each side of the tubular slit screen.

Each tri-layer laminate includes an outer filtration screen 32, which has a circular shape and is e.g. 24 x 110
It has a relatively fine mesh, comparable to a "Dutch" or HF75 stainless steel screen, and is welded to one side of the closure member around its entire circumference by a continuous weld bead 33. For example, a circular coarse screen 34 of 16 mesh stainless steel wire underlies each fine screen, and perforated plates 36 are mounted on each side of the tubular slit screen. Preferably, the perforated plate is made of 20 gauge stainless steel drilled with 3/16 inch (4.8 mm) holes spaced 1/4 inch (6.4 mm) on centers. As mentioned above, the outer filtration screen, coarse screen and perforated plate of each trilaminar layer are diffusion bonded together to form a relatively rigid structure. The fine screen and perforated plate each have a diameter slightly smaller than the inner diameter of the closure ring. The diameter of the coarse screen is slightly larger than the inner diameter of the closure ring and overlaps the inner edge of the ring.
Installed here is a specific screen approximately 1/8in (3.2mm) providing material for welding. In practice, the overlap should be as small as possible to minimize the space between the fine screen and the non-welded parts of the closure ring. This portion of conventional filter leaves provides an undesirable trap for solid debris filtered from the liquid, inhibiting proper purification of the filter leaf. This problem is reduced by the present invention.

As described in more detail below, the three-layer diffusion adhesive thin layer secured to the closure ring as shown in FIG. 2 forms a tight "coat" on both sides of the closure ring. Each "coat" is relatively rigid due to the diffusion bonding of the three layers and their placement on a tubular slit screen which itself provides rigid support. There are no wrinkles or sag in the thin layer, and the metal screen does not work harden even when the filter leaves are reused through various stages of the filtration process. The filter leaf therefore has a long and reliable service life even under harsh conditions of use. The apparatus for manufacturing the filter leaves shown in FIGS. 1 and 2 is shown in FIGS.
It is shown in Figure 0.

The device includes an upright frame 40 supported on supports 42. The frame includes on its underside a pair of elongate, parallel, horizontal channel beams 44, each beam welded at each end to a corresponding foot 46,47. Each leg consists of a horizontal grooved beam resting on a support 42. Each integral vertical leg 49 is secured at its lower end to a foot 46,47. An upper pair of elongate, parallel, horizontal channel beams 52 are secured at each end to the upper end of each leg 49.

A rotatable circular horizontal bottom plate 60 is supported at the upper end of a vertical drive shaft 62 journalled in a thrust bearing 64 supported by a bracket 66 from the lower channel beam 44. The lower end of the drive shaft supports a pulley 68 driven by a belt 70;
Belt 70 is driven by a drive pulley connected to variable speed motor 76 via shaft 74 . As shown in FIG. 8, the bottom plate 60 includes an annular upright wall 80 around its entire periphery. An annular inwardly extending horizontal step 82 at the bottom of wall 80 terminates in a circular upwardly open cavity 84 .
During the welding operation, the closure ring 20 rests on the step 82. The outer surface 86 of the ring abuts the inner surface of the upright wall 80 and is centered relative to the center of the base plate and the axis of rotation of the drive shaft 62. As shown in FIG. 8, the first three-layer diffusion adhesive thin layer 26 is already welded to the bottom side of the closure ring, and the outer filter screen 32 is already welded to the bottom side of the closure ring.
fits tightly within the circular cavity 84 adjacent to the inner edge of the horizontal step 82 . The second three-layer diffusion bond thin layer 28 is in the process of being welded to the upper side of the closure ring by a high energy welding beam 90, such as a gas or crystal laser, or an electron beam, provided by a source 92. Of course, if an electron beam is used, the entire apparatus is preferably enclosed within a vacuum chamber (not shown).

As shown in FIG.
extends substantially completely across the upper side of the closure ring 20 to ensure suitable material is welded to the ring.
However, in practice, welding is carried out as close as possible to the inner surface of the ring. For example, the weld preferably extends 0.1 to 0.2 inches (2.54 to 5.08 inches) from the inside surface of the ring.
mm). As a result, the outer filtration screen 32 has a downwardly extending annular wall 96 on the underside of a circular backing plate 98 that is supported concentrically above the bottom plate 60.
is clamped against the upper side of the closure ring (in FIG. 8).

The outer diameter of the holding plate is 1/8in than the inner diameter of the closing ring
(3.2mm) larger, so the overlap is about 1/16in (1.6mm)
becomes.

The presser plate has a spider 10 fixed to the upper surface of the plate.
0, the spider is supported by the upper beam 5
The air cylinder 104 is supported via a vertical piston rod connected to a piston (not shown) in an air cylinder 104 secured between the two. Compressed air is supplied to both ends of the cylinder by known members (not shown);
The piston, piston rod, spider, and retainer plate are movable up and down relative to the bottom plate to clamp the closure ring and outer filter screen as shown in FIG. As mentioned above, the diameter of the retainer plate is only slightly larger than the inner diameter of the closure ring. For example, if the closure ring has a content of 47 inches (1194 mm), the outer diameter of the retainer plate will be 47 1/8 inches (1197 mm). As shown in FIG. 8, the thickness of the downwardly extending annular wall 96 on the lower surface of the retainer plate is equal to the amount that the retainer plate overlaps the inner edge of the closure ring. If desired, the annular wall 96 can be removed so that the bottom surface of the retainer plate is flat. This provides firm contact of the bottom surface of the backer plate against substantially the entire outer filter screen when the backer plate is lowered into the clamped position as shown in FIG. This creates a smooth working edge on the screen and eliminates wrinkles that would appear before welding.

As shown in FIGS. 5, 6, and 9, a curved leaf spring blade 110 extends downwardly from a fixed bracket 112 that is supported adjacent the top surface of the bottom plate periphery. The blade extends generally tangentially downward toward the bottom plate and curves upwardly in a concave manner. The lower end of the curved plate blade contacts the upwardly facing outer filter screen and is adjacent to the periphery of the retaining plate 98 and against the upper surface of the closure ring at a location just before the screen passes below the welding beam 90. Hold the screen to make firm contact. As shown in FIG. 6, the lower plate 60, the closure ring 20, the outer filter screen 32, and the retainer plate 98 move from right to left as indicated by the arrows, and the weld bead is formed at the position where the welding beam 90 hits the screen and closure ring. 33 is formed. At this location, the beam cuts the screen by melting. The beam also at the same time immediately penetrates and dissolves the part of the ring lying below the cutting screen. The molten metal from the two parts melts, cools, and solidifies;
A weld bead is formed that adheres the inner portion of the screen to the ring, and the outer portion of the screen remains without removal.

As best shown in Figures 4, 8 and 9,
The welding beam is inclined at an angle A with respect to the main plane of the filter leaf, so that the angle between the beam and the main plane of the filter leaf is approximately 40°. It has been found that this angle is actually convenient for cutting the screen and creating a weld bead that simultaneously dissolves the ring and leaves the outer portion 13 of the screen. If this angle increases above about 50 degrees, inadequate welding and incomplete cutting of the screen will result. If this angle is reduced to 30°, the bead will bounce on the workpiece and will not melt the metal.

Also, by arranging the outer filter screen as shown in FIG. 8, i.e. by using a substantial portion projecting outwardly from the retainer plate and beyond the top surface of the closure ring, it is possible to press the outer edge of this projecting screen. This is advantageous and ensures contact between the screen and the closure ring at the locations where they are impacted by the welding beam.

Finally, an annular clamp ring 120 (only shown in FIG. 8) attaches bolts 122 to the top surface around the bottom plate.
Fixed by The retainer ring includes an annular inwardly and downwardly extending flange 124, the outer end of which has a horizontal surface 126 on the underside and contacts the outer filtration screen slightly outside the path followed by the welding beam as the apparatus is rotated. do.

Desirably, the bottom plate, retainer plate and clamp ring are all made of a material that has a higher thermal conductivity than the material to be welded, which typically consists of stainless steel.
For example, the thermal conductivity of stainless steel is 113 BTU/
ft ²・hr・〓・in (27kcal/m ²・hr・℃・cm), whereas aluminum is 1390 (2674), copper is 2700 (5139), and silver is 2900 (5578) (each value The unit of thermal conductivity is the same as for stainless steel above. Aluminum, copper, silver, or alloys of these or similar metals are used for the bottom plate, holding plate, clamps, etc.
When used for rings and retainer blades, heat can be quickly dissipated from the weld area to prevent overheating, overstretching, and stress relief of the closure ring.

To protect the metal during welding, an inert gas, such as argon or helium, is injected through a flexible gas tube 130 connected to a vertical cavity 132 extending through the hold-down plate. An inert gas is forced into the space between the holding plate, the annular ring and the bottom plate. Gas escapes through the unwelded portion of the outer filter screen. The screen and closure ring are therefore flooded with an inert gas from the inside out to isolate oxygen from the molten metal during the welding operation. This reduces sputtering of the molten metal, produces a better weld, and prevents contamination of the lens (not shown) used to focus the welding beam when a laser source is used. Inert gas is also supplied to the welding area outside the holding plate.

As previously mentioned, high energy welding beam 90 can be provided from a variety of suitable sources.
Ordinary carbon dioxide or YAG (yttrium)
The leather (aluminum-garnet) heats up a very small area and the closure ring is not overheated during the welding operation, resulting in good welding. this is,
In conjunction with the heat transfer provided by the aluminum enclosure, amazing results have been obtained in welding the screen to a continuous closure over its entire circumference;
Even after welding, the closure member does not shrink and the screen does not wrinkle. This provides a filter leaf that has a long life even under harsh conditions of use.

During the welding operation shown in FIG. 8, the high energy welding beam 90 cuts by melting the screen and penetrates the upper surface of the closure ring or member just outside the perimeter of the backing plate. The result is an annular weld bead 33 shown in FIG. Surprisingly, the weld beads adhere to the closure ring around only the inner part of the screen, leaving the outer part of the screen free. The bead has an inwardly and downwardly extending annular flange 134 such that the inner portion of the screen is not only sealed against the closure ring around the entire perimeter of the screen, but also has an inwardly and downwardly extending annular flange embedded within the closure ring. It is mechanically secured to the closure ring by an elongated flange 134.

An important advantage of the present invention is that the screen can be cut and welded simultaneously at 20% per minute using known laser equipment.
This can be done at a relatively high speed of 80 inches (0.5 to 2 m). This is substantially faster than acetylene oxide gas or inert gas arc welding, which is limited to speeds on the order of about 2 to 3 inches (5 to 7.6 cm) per minute. Additionally, acetylene oxide gas or inert gas arc welding overheats the ring, causing the screen to wrinkle as the ring cools.

Once welding is complete, the clamp ring is removed and the cut area of the outer filter screen is removed. If the wires are cut incompletely, they will break when bent back and forth. The unmelted wire is then "flame polished", e.g.
By moving the rotation center of the lower side and the holding plate to the right in the figure so that it is about 0.020 inch (0.51 mm) away from the position where the welding beam hits the processed part, it fuses with the weld bead. The process is then repeated and the welding beam impinges on the protruding wires, melting and fusing them together with the welding beam.

To move the center of rotation as described above, a vertical pivot pin 140 attaches the foot 47 to the support 42, and the frame 40 can pivot in a horizontal plane about the upright axis of the pivot pin. The other foot 46 can slide on the support 42 and be moved from side to side (in FIG. 4) by means of an adjustment nut 144 welded to the foot 46 and threaded onto a horizontal screw 146 on the opposite side of the vertical plate 148. Ru. One end of screw 146 is secured to a bracket 150 welded to support 42, and the other end extends through an opening (not shown) in plate 148. Therefore, when the nut 144 is rotated, the frame will rotate against the pivot pin 14.
It can be positioned accurately by rotating around 0. Alternatively, legs 46 and 47 can be supported to slide in spaced paths on their respective supports, so that the center of rotation moves along a straight line rather than a curve.

FIG. 10 shows a modified embodiment of the invention in which a cutting wheel 16 is disposed adjacent the periphery of a backing plate 98.
0 is supported and rotates about a horizontal shaft 162 on the lower end of an upwardly extending bracket 164 secured to the support by suitable members (not shown). A normal adjustment member (not shown) is attached to bracket 1.
64 and shaft 162 are provided to move the shaft 162 up and down relative to the bottom plate 60 so that the cutting wheel engages an outer filtration screen that rests on the closure ring 20. The bottom plate is rotated at a suitable speed and a cutting wheel cuts through the outer filter screen.
The cut portions of the screen are removed and the remaining screen is then welded to the closure ring as described above. The advantage of the device shown in Figure 10 is that a high-energy welding beam does not have to be used for the cutting operation, and therefore less time and force are required, melting only the parts of the screen and closure ring that form the weld bead. In addition, it is sufficient to concentrate the beam on melting.

Although the present invention has been described in detail with respect to stationary filter leaves, it is understood that rotating filters can also be made in accordance with the present invention. In fact, the filter leaves can be of various shapes, such as square, rectangular, triangular, oval, etc.
It is also possible to have only one screen. For example, FIG. 11 shows a pan-shaped filter leaf that includes a narrow pan 170 (closure member) having a flat, square or rectangular bottom 172 and an upwardly extending wall 174 around the perimeter of the pan bottom. The outer filtration screen 176 is used to operate the processing section or laser source according to the invention described above.
The Y-table is used to form a continuous weld bead 180 around the entire perimeter of the screen that is welded to the top edge of wall 174 and adheres the screen to the top edge of wall 174. A filtrate space is thus formed between the screen and the closure member or pan 170. A drain pipe 182 in the center of the pan removes the filtrate. If desired, a coarse screen 184 may be disposed within the pan to
76 is supported.

FIG. 12 is a longitudinal sectional front view of a plate-type filter leaf 190, which includes a plurality of radially extending ribs 194 on the upper surface.
It includes a circular plate 192 (closing member) having a circular plate 192 (closing member). The ribs converge at the center of the plate and have transverse drain holes 196 extending through them to allow filtrate (not shown) passing through a filtration screen 198 on the ribs to flow to a common outlet 200. The filter screen 198 has weld beads 20 around its entire circumference.
2 around the periphery of plate 192, defining the filtrate collection space between the filter screen and the plate or closure member. The plate includes as many ribs as are necessary to support the screen, depending on the conditions in which the filtration device is used.

From the foregoing description, it is apparent that the present invention provides an improved filtration screen that is quickly and easily manufactured by welding the components together with a high energy welding beam, wherein the filter leaves are welded together. The surrounding closure does not shrink after the welding operation, thus preventing the formation of wrinkles that can lead to premature damage under severe loading conditions. Additionally, the weld bead is proximate to the inner edge of the closure member, substantially eliminating dead space that could trap and retain undesirable material during filtration and cleaning.

Although the invention has been described in a manner in which the welding beam is stationary while the workpieces to be welded are rotated, the opposite configuration is also possible, where the workpieces are stationary while the beam is moving. For example, the source of the welding beam may be supported on an X-Y mathematical control table to cause the welding tangent to follow a desired trajectory. Alternatively, the bottom plate and the hold-down plate can be supported on an X-Y table for control actuation in a manner known to those skilled in the art.