Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Reshaping running or indefinite-length work
Patent
1981-01-22
1984-02-21
Czaja, Donald E.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Reshaping running or indefinite-length work
26 186, 162111, 162280, 162281, B31F 114, D06C 2100
Patent
active
044329270
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the creping (especially microcreping) of sheet material and especially of fibrous sheet material e.g. paper. The invention involves a departure from prior microcreping apparatus and methods such as the commercial "MICREX" machine and process as taught, for example, in U.S. Pat. Nos. 3,260,778 and 3,426,405.
A cross-section of the treatment zone of such a prior machine is illustrated in simplified and schematic form in FIG. 1 of the accompanying drawings. The machine has a driven rotary roll 1, a retarder blade 2 with blade edge 3 and retarding working surface 9, and a covering resilient spring blade 4 projecting from a blade assembly 6. The roll rotates in the direction of the arrow. The sheet to be micro-creped is pressed onto the roll by means of blade assembly 5 via the blade assembly 6 and leaves at 7 after going through cavity 8 and between blades 2 and 4. The sheet itself is not shown in this Figure. The area inside the dotted rectangle of FIG. 1 is shown on a more enlarged scale in FIG. 2 of the accompanying drawings.
According to U.S. Pat. No. 3,260,778 (column 7, lines 42-66), the retarding working surface 9 is disposed with its edge 3 adjacent the roll 1, so that an acute angle .alpha. is included between the retarding surface 9 and the direction of movement of the portion of the roll surface passing under the retarder edge 3. The angle must, according to this U.S. patent, be acute, and not closely approach a right angle, as the latter would cause jamming of the machine. Moreover, according to this U.S. patent, the angle must be substantial, in order to create resistance forces and to obtain disengagement of the sheet material from the roll 1 without contact with the retarder edge 3.
Because of this requirement that the sheet material should not contact the retarder edge 3, a machine based on these U.S. patents is not so much a creping machine, but relies more on a stuffer box effect between blades 2 and 4.
The present invention, in contrast, obtains creping by purposely directing the sheet into impingement against a transverse upstream-facing wall of the retarder--which may be a blunt upstream edge 3 of the retarder or a step in its upper surface 9--the dimensions of the treatment cavity immediately upstream of the transverse wall being such that said impingement and creping occurs.
The present invention provides a creping machine comprising a driven rotary carrier roll; a stationary blade assembly which is positioned to press sheet material into entrained engagement with the circumferential surface of the carrier roll and which includes a resilient spring blade projecting downstream from the immediately adjacent portion of the assembly; and a stationary retarder extending downstream from the circumferential surface of the carrier roll adjacent to the projecting resilient spring blade and over which the sheet material passes on disengagement from the said surface; the retarder having a transverse upstream-facing wall extending downwardly from its upper surface whereby a cavity constituting a creping zone is defined upstream of the said wall and beneath the projecting resilient spring blade.
The said transverse upstream-facing wall may constitute the upstream extremity of the retarder, or an intermediate step interrupting the upper surface of the retarder. In the latter case, the retarder may be an integral body or a composite of a base member having a plate or blade secured to its upper face to provide the step.
Since the machine and method according to the invention involve a true creping action, rather than relying mainly on pressure and friction between blades 2 and 4 and the sheet material, they permit working at lower pressures and friction than necessary heretofore (thus satisfactory microcrepes have been obtained according to the invention, with paper about 0.1 mm thick, using a pressure as at P, FIG. 1, of less than 100 g/cm). Lower operating pressure and friction can have the advantage of less heat generation (avoiding problems when heatsensitive binders are us
REFERENCES:
patent: 1751471 (1930-03-01), Campbell
patent: 2567967 (1951-09-01), Rowe
patent: 3426405 (1969-02-01), Walton
patent: 4078958 (1978-03-01), Patin
patent: 4142278 (1979-03-01), Walton et al.
van Tilburg, administrator by Yolande E.
van Tilburg, deceased Jan
Czaja Donald E.
Housel James C.
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