US 3126332 A
Description (OCR text may contain errors)
March 24, 1964 F. sALETE SIFTING FRAME Filed May 19. 1961 Magik United States Patent Of ice 3,126,332 Patented Mar. 24, 1964 3,126,332 SIFTING FRAME Felipe Salete, Mexico City, Mexico, assignor to Refaccionaria de Molinos, SA., Mexico City, Mexico Filed May 19, 1961, Ser. No. 111,296 1 Claim. (Cl. 209-408) rThis invention relates to a clamping device for use in securing a sifting cloth in a frame for purifiers and classiers of various types.
More specically, this invention relates to a sifting frame with a special device for xng and tightening the sifting cloth for use in special machines for classifying ground materials. The sieve frames known at the present time have serious drawbacks, for instance, when placing the sifting cloth in the frame since there the frames are of wooden construction where the sifting cloth is tacked or nailed, and in addition to the excessive work involved, it is difficult to achieve a uniform tension, and also, if a cloth is taken oi from a sieve frame it will become useless for further service.
There are other types of sifting frames which have cloth stretching systems and devices with steel rods of round section that are introduced in seams previously made on the cloth to be stretched and secured by screws.
The main inconvenience of the systems used heretofore is that it is required to make a special manufacture of the cloth With seams on its four sides which makes it imperative to have a constant stock on hand to change the ones that are torn or worn out, or when it is desired to use a cloth of a diierent mesh number. Also the previous systems have a further disadvantage that the steel rods of round section become bent between the points where the screws are placed, resulting in the creation of zones of less tension and with the danger of tearing the cloth unless special care is taken when stretching it. Another disadvantage is that the screws push the steel rod through the cloth which deteriorates and tears result due to the direct contact of the screws. The present invention eliminates the various drawbacks mentioned in the foregoing.
It is therefore an object of the invention to provide a sifting frame in which the fixing and tightening of the cloth is evenly achieved as to the entire surface using any type of cloth and preventing every possible risk of tearing or damage.
A further object of the invention resides in the structure of the sifting frame which has a section resembling a hook with at least four channel bars one at each side of the frame on which the sifting cloth is placed, guided, and held by four bars of rectangular or square section, located inside the channels bars. The sifting cloth is wrapped around the bars in such a way that when adjusting the bars the wrapped cloth is tightened from its initial position and secured against the hook sections by two edges of the rectangular section bars which are pressed by means of screws to thus maintain the cloth aligned and with the required tension.
Further objects and advantages will be apparent from the following description when considered in connection with the accompanying drawings, in which:
FIGURE 1 is a side elevation,
FIG. 2 is a cross sectional view of the frame of FIG. 1,
FIG. 3 is a sectional view of the details of one frame side showing the placing of the sifting cloth on the frame,
FIG. 4 is a sectional View similar to FIG. 3 showing the cloth clamped in the securing means, and
FIG. 5 is a sectional view similar to FIGS. 3 and 4 showing the sifting cloth secured in stretched condition.
Referring now more particularly to the drawings and especially to FIGS. 1 and 2, a cloth holding device consists of a frame 1 having a section like a hook 7 around which the siftting cloth 6 is provided and is introduced into the channel member 2, pushed by a bar 3. Channel 2 receives the end of the cloth 6 and the bar 3, after which the channel member 2 is elevated as pressed and guided by screws 5 which are threaded in caps or plugs 4 which are secured to the frame, thereby placing the cloth under tension.
In securing the sifting cloth the latter as in FIG. 3 is placed over the empty channel frame 1 with the channel member 2 in its lowered position and the bar 3 is out of the channel. With the cloth in the position or FIG. 3, the bars 3 are pushed into the respective channel members to force the cloth ahead and in position as shown in FIG. 4 which is the second placing stage of the sifting cloth wedged in channel 2 wherein in this position the screws 5 are now rotated to thereby stretch the cloth by forcing the channel member 2 with its bar 3 upwardly to pull the cloth 6 tightly across the frame 1. Thus the action rmly presses the cloth against the sides of the channel 2 through one upper and lower edge of bar 3 as the bar cannot slip out of the channel since the hook frame will not permit such movement. FIG. 5 therefore shows the cloth firmly clamped in position.
By rotating the screws 4 in the opposite direction, the channel members 2 and its bar 3 will be lowered to the position of FIG. 4 to permit the removal of the bars 3 so that the cloth or fabric sieve may then be removed.
A sifting device for sifters and classifiers comprising a rectangular frame having a U-shaped part in cross-section in one end thereof, a U-shaped channel member positioned adjacent and being slidable along a long side of the frame and into a pocket of the U-shaped part, a rectangular bar adapted to be inserted into the U-shaped channel member to clamp and hold a fabric cloth stretched over the frame, and means in the form of a threaded plug member connected to the other end of the frame and a screw in threaded engagement with the threaded plug member and rotatably mounted in the U-shaped channel member to force the channel member and its bar with the fabric clamped therein into the pocket of the U-shaped part of the frame to stretch the fabric over the frame and hold it in tight stretched condition.
References Cited in the file of this patent UNITED STATES PATENTS 129,665 Howard July 23, 1872 1,897,418 Carlson Feb. 14, 1933 2,702,633 De Kanski Feb. 22, 1955 2,808,880 Frick Oct. 8, 1957 FOREIGN PATENTS 724,985 Great Britain Feb. 23, 1955 1,056,460 Germany Apr. 30, 1959