Textiles: fiber preparation – Working – Carding
Reexamination Certificate
1999-11-18
2001-08-07
Worrell, Danny (Department: 3741)
Textiles: fiber preparation
Working
Carding
C019S102000, C019S104000
Reexamination Certificate
active
06269522
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a carding arrangement which has a drum with a drum fitting and a plurality of card flats. Each card flat is provided with a card flat fitting, wherein the card flat can move relative to the drum along a predetermined path while maintaining a predetermined distance between the drum fitting and the card flat fitting. A running surface of each card flat fitting is in contact along the predetermined path with a guide surface defining the predetermined path. The invention also relates to a card flat for carrying out the method.
Cards operating according to the aforedescribed method are used to orient individual fibers of a raw material, for example material used in the manufacture of yarn. The operation of such a card is as follows: The card includes basically a drum and a several card flats. The second drum is essentially shaped as a circular cylinder and includes a fitting arranged on its outer surface. The fitting of the card is formed of individual wire hooks inserted into a rubber fabric. Alternatively, fittings in the form of saw-tooth wires which helically surround the cylinder axis of the drum, can also be employed. During the operation of the card, the drum is rotated about its cylinder axis.
The card flats are secured to a continuous transport element, such as a transport belt or a transport chain. The transport element can be used to move the card flats relative to the drum along a predetermined path extending approximately parallel to the outer surface of the drum and to then return the card flats above the predetermined path. The transport direction of the card flats along the predetermined path opposes the rotation direction of the drum. The side of each card flat which faces the drum fitting along the predetermined path, has a card flat fitting. The card flat fittings of the card are formed as a wire fabric which is inserted into a rubber fabric.
To orient the individual fibers parallel to each other, raw material provided, for example, in the form of cotton flakes, is supplied to the drum by a taker-in or a supply drum. The taker-in includes a saw-tooth fitting made entirely of steel. The supplied material is captured by the drum fitting and entrained in the rotation direction of the second drum. The fibers entrained by the drum fitting are flattened by the card flats which move along the predetermined path in a direction opposing the rotation direction of the drum. This process produces on the drum fitting a fine pile of oriented fibers which can be removed from the drum with a stripper roller (not shown) for further processing.
For proper carding, the tips of the card flat fittings moving along a predetermined path in the opposite direction of the rotation direction of the drum have to maintain a predetermined distance of approximately 0.15 to 0.18 mm from the tips of the drum fittings. For this purpose, the individual card flats typically have card flat rods supporting the card flat fittings, with hardened guide pins fixedly secured in the card flat rods. The card flat running surfaces formed by the guide pins contact at least along the predetermined path a sliding guide which is typically made of plastic. Card flats of this type are disclosed, for example, in U.S. Pat. No. 5,473,795.
It has been observed that with cards operated in the manner, the carding effect deteriorates with increasing operating time. The drum fittings and the card flat fittings may also be damaged with increasing operating time. These defects are commonly eliminated by applying new fittings to the drum and the card flat, thereby eliminating the defects caused by wear of the fittings. However, it has been observed that even after applying new fittings to the drum and the card flats, the original carding efficiency obtained when the card was first put in service, could no longer be attained and that the fittings were again damaged after operating only for a short time.
SUMMARY OF THE INVENTION
In view of these problems encountered in conventional methods, it is an object of the invention to provide a method for operating a card, wherein short-term damage to the fittings can be prevented and the original carding efficiency obtained at the time, when the card was first put in service, is maintained even after the installation of new fittings. It is a further object of the invention to provide a card flat which can be used for carrying out the method.
According to the invention, the object is solved by improving known methods of operating a card. More particularly, the predetermined distance between the drum fitting and the card flat fittings is adjusted by conditioning the running surfaces of the card flats.
The present invention is based on the observation that the carding effect during long-term operation of a card does not only deteriorate due to wear of the fittings, but also due to contamination and/or wear of the card flat running surfaces. A degradation of the card flat running surfaces can decrease the separation between the fitting tips of the card flat fittings and the fitting tips of the drum fittings to a value of less than 0.15 mm, which can damage the fittings even if new fittings are applied to the card flats and the drum.
The aforedescribed deficiencies can be eliminated with the method according to the invention by conditioning the card flat running surfaces. Conditioning may include removing contamination from the card flat running surfaces in order to counteract an unwanted increase in the distance between the fitting tips of the card flat fittings and the fitting tips of the drum fittings. Conditioning may already be performed when the cards are cleaned.
According to a preferred embodiment of the invention, conditioning may include machining the card flat running surface. In this way, wear of the card flat running surfaces which may cause the card flats to move irregularly along the predetermined path, can be prevented by the method of the invention through remilling or regrinding the card flat running surfaces. According to a particularly preferred embodiment of the invention, a profile milling machine and/or a profile grinding machine may be employed for this operation.
The method according to the invention may be carried out by using—at least in the region of the card flat running surface—card flats made of gray cast iron. Such card flats may advantageously be produced by using card flat rods produced as a single piece which includes the guide elements forming the card flat running surface and the support member forming the contact surface for the card flat fittings.
According to still another preferred embodiment of the invention, to provide excellent wear resistance without increasing the weight of the card flats, the card flat running surface may be formed by at least one running surface member having a fixed position relative to a support member of the card flat and being made of a material which is harder than the material of the support member.
Such running surface member may, for example, have the form of a pin made of hardened steel and inserted into a corresponding aperture in the support member. To precisely guide the card flat along the predetermined path, the card flat for carrying out the method of the invention advantageously comprises at least two running surface sections which are spaced apart from each other in the direction of the predetermined path. The two running section members may advantageously be affixed to the support member of the card flat.
If the pins have a substantially circular cross-section, the card flat running surface and the guide surface can advantageously be prevented from pressing against each other across the entire surface area by flattening the pin, which forms the running surface member, in the region of the card flat running surface, so that the pin has a substantially rectangular surface region. The running surface member may be secured to the support member in a force-transmitting engagement, form-fitting engagement and/or material engagement
Geisser Stefan
Graf Ralph A.
Darby & Darby
Graf & CIE AG
Welch Gary L.
Worrell Danny
LandOfFree
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