JP2877668B2 - Vacuum forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vacuum forming method for forming interior materials for automobiles and the like.
More specifically, the present invention relates to an improvement in a vacuum forming method for transferring a sheet heated in a sheet heating station to a vacuum forming station and performing vacuum forming.

[0002]

2. Description of the Related Art In the above vacuum forming method,
It is inevitable that the heated sheet in the sheet heating station will draw down, but if the drawn down sheet approaches the heater excessively, a problem may occur. Therefore, as shown in, for example, Japanese Utility Model Application Laid-Open No. 59-7814, the approach is prevented by lowering the lower heater in accordance with the draw down amount of the sheet.
A technology has been developed to prevent approach by adjusting the stretch amount of the seat according to the draw down amount of the seat.

However, in such a conventional technique, only the drawdown amount of the sheet in the sheet heating station is controlled, and the holding of the sheet in the middle of transferring the heated sheet from the sheet heating station to the vacuum forming station is carried out. Drawdown by heat is not controlled. For this reason, the draw-down portion of the sheet transferred to the vacuum forming station may adhere to the base material prior to the vacuum forming, and the vacuum forming may not be performed smoothly, and irregularities may occur.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and optimizes not only the drawdown of a sheet at a sheet heating station but also the drawdown of a sheet transferred to a vacuum forming station. The present invention has been completed in order to provide a vacuum forming method capable of performing vacuum forming smoothly by controlling.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vacuum forming method for transferring a sheet heated in a sheet heating station to a vacuum forming station and vacuum forming the sheet. The drawdown speed is detected while performing the primary stretch according to the drawdown amount of the sheet, and the secondary stretch amount in the vacuum forming station is controlled according to the value.

[0006]

According to the present invention, since the primary stretching is performed in the sheet heating station in accordance with the amount of draw down of the sheet, it is possible to prevent the drawn down sheet from excessively approaching the heater. Further, since the drawdown speed in the sheet heating station is detected and the amount of secondary stretching in the vacuum forming station is controlled according to the value, the drawn down sheet adheres to the base material prior to vacuum forming. Therefore, vacuum forming can be performed smoothly.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the illustrated embodiments. FIG. 1 is an overall view of a vacuum forming machine used in the present invention, 1 is a sheet conveying device, 2 is a sheet heating station, and 3 is a vacuum forming station. The sheet S made of synthetic resin is heated at the sheet heating station 2 and then transferred to the vacuum forming station 3 where it is vacuum formed.

FIG. 2 shows a sheet heating station 2 in which a sheet S whose peripheral edge is chucked by a sheet clamp 4 is horizontally held between an upper heater 5 and a lower heater 6 and heated. At this time, the sheet S is softened by heating and draws down. However, a drawdown sensor 7 such as a photoelectric tube is installed below the sheet clamp 4 to detect the drawdown amount.
Then, in order to prevent the drawn-down sheet S from abnormally approaching the lower heater 6, the sheet clamp 4 is moved outward in accordance with the draw-down amount to perform the primary stretching of the sheet S as shown in FIG. Further, the time from the start of heating the sheet S to the detection of the drawdown by the drawdown sensor 7 is measured by a timer, and the drawdown speed is also detected.

When the heating level of the sheet S reaches the target value, the sheet S is transferred to the vacuum forming station 3. At this time, in the present invention, before the sheet S comes into contact with the base material, the sheet clamp 4 is again moved to
Add the next stretch (see Figure 3). This is an operation for removing the influence of drawdown due to retained heat while the sheet S is transferred to the vacuum forming station 3. At this time, the required amount of the secondary stretch varies due to the fluctuation of various conditions.
Control the next stretch amount.

That is, when the drawdown speed detected at the sheet heating station 2 is high, the drawdown amount during the transfer is estimated to be large, and the secondary stretching amount is increased. If the drawdown speed is low, the amount of secondary stretching is reduced by estimating that the amount of drawdown during transfer is also small. By performing the secondary stretching controlled as described above, the drawn-down sheet S does not adhere to the base material prior to the vacuum forming, so that stable vacuum forming can be always performed. Table 1 below shows examples of the secondary stretch amount, and FIG. 4 shows a block diagram of the present invention.

[0011]

[Table 1]

[0012]

As described above, according to the vacuum forming method of the present invention, it is possible to control the draw down of the sheet in the sheet heating station and prevent the drawn down sheet from abnormally approaching the heater. it can. Moreover, according to the vacuum forming method of the present invention, the drawdown of the sheet transferred to the vacuum forming station can also be optimally controlled, and the vacuum forming can be performed smoothly regardless of the material of the sheet. Therefore, the present invention greatly contributes to the industry as a vacuum forming method that solves the conventional problems.

[Brief description of the drawings]

FIG. 1 is an overall view of a vacuum forming machine.

FIG. 2 is a side view illustrating primary stretching in a sheet heating station.

FIG. 3 is a side view illustrating secondary stretching in the vacuum forming station.

FIG. 4 is a block diagram illustrating steps of an embodiment.

[Explanation of symbols]

 2 Sheet heating station 3 Vacuum forming station S sheet

Claims (1)

(57) [Claims] In a vacuum forming method for transferring a sheet (S) heated in a sheet heating station (2) to a vacuum forming station (3) and vacuum forming the sheet (S), drawing of the sheet (S) in the sheet heating station (2) is performed. A vacuum forming method comprising: detecting a drawdown speed while performing a primary stretch according to a down amount; and controlling a secondary stretch amount in a vacuum forming station (3) according to the value.