Title:
CONTROLLING METHOD OF LENGTH OF PARISON IN BLOW MOLDER
Document Type and Number:
Japanese Patent JP2614570
Kind Code:
B2
Abstract:
PURPOSE: To highly accurately control the length of parison and consequently enhance the accuracy of the wall thickness of a product by a method wherein the rotational frequency of a screw is controlled on the basis of the difference between the length of the extruded parison and the target length under the condition that the relationship between the rotational frequency of the screw of an extruder and the length of parison to be extruded is obtained in advance.
CONSTITUTION: By obtaining the difference (t) between the time required by parison for being cut with a cutting device and the time required by the parison for passing through a photoelectric tube, which is provided below the die head of an extruder (or light exclusion time by parison), the value equivalent to the length of the parison can be set. There is a proportional relationship between 1/t and the rotational frequency N of the parison. By changing the rotational frequency by ΔN to the deviation Δt of the light exclusion time, the target length of the parison can be ensured. At this time, the scattering of the length of the parison (or light exclusion time (t)) in the comparatively short period of time (or standard deviation (σ)) is calculated so as to set a dead zone (3σ). When the difference of the light exclusion time by parison falls out of the dead zone, the rotational frequency N of the screw is preferably corrected.
More Like This:
Inventors:
Tokuji Noguchi
Yano Masashi
Akimoto Masayuki
Mitsuo Yamanoi
Minoru Oizumi
Yano Masashi
Akimoto Masayuki
Mitsuo Yamanoi
Minoru Oizumi
Application Number:
JP35817891A
Publication Date:
May 28, 1997
Filing Date:
December 27, 1991
Export Citation:
Assignee:
Kao Corporation
Tahara Co., Ltd.
Tahara Co., Ltd.
International Classes:
B29C49/04; B29C49/78; B29B11/10; B29L22/00; (IPC1-7): B29C49/04; B29B11/10; B29C49/78
Attorney, Agent or Firm:
Shuji Shiokawa