JPH0436259Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a plurality of set roll forming apparatuses, commonly called polishing stands, which are applied to a sheet forming section in a plastic sheet manufacturing apparatus.

(Prior Art) Usually, a plastic sheet manufacturing apparatus has a configuration as shown in FIG.

In the figure, numeral 1 melts the plastic raw material supplied by the extruder using an electric heater and a drive motor attached to the outside of the cylinder, and extrudes it.

There is a T-die 2 at the tip of the extruder 1, and the molten plastic raw material extruded from the extruder 1 is discharged from the slit-like gap of the T-die 2 in the form of a sheet with a predetermined width and thickness. .

3 is a forming device commonly called a polishing stand, which is composed of a group of rolls with water or a heat medium flowing inside to keep the surface at a low temperature.
The sheet discharged from the die 2 is simultaneously cooled and pressed by the roll group, and is cooled and solidified to a predetermined width and thickness.

Reference numeral 4 denotes a take-up machine, which is installed on the same pedestal as the polishing stand 3, and presses and takes off the sheet cooled and solidified by the polishing stand 3 between built-in rolls.

Reference numeral 5 denotes a cutting machine, which is placed after the take-up machine 4 and measures the cooled and solidified sheet to a predetermined length, cuts the sheet while moving, and returns to the original position after cutting is completed to perform the same work. is becoming repetitive. The cut sheets are stored in the stocker 6.

Next, a conventional polishing stand to which the present invention is applied will be specifically explained with reference to FIGS. 4 to 7.

In the figure, reference numerals 10, 11, and 12 are polishing rolls arranged in the upper, middle, and lower stages, and their axes are aligned on the same vertical plane.The surfaces of each polishing roll are mirror-finished, and water or a heat medium is passed through the inside. to keep the surface cool. The distances a and b between the three polishing rolls 10, 11, and 12 can be adjusted by appropriate means.

Reference numeral 13 denotes a lower take-up roll, which has a mirror-finished surface and is pivoted to be driven and rotated at a predetermined position. Reference numeral 14 denotes an upper take-up roll, which is usually a rubber roll, and is pivotally supported so that it can forcibly press the lower take-up roll 13.

15 to 18 are each polishing roll 10, 11,
12 and the lower take-up roll 13 each drive motor,
Each one drives each roll via worm reducers 19-22.

Each worm reducer 19-22 is a reducer for the upper, middle and lower polishing rolls 10, 11, 12 and the lower take-up roll 13, and the respective drive motors 15-18
It is connected to each roll through a special joint.

Reference numeral 23 denotes a rotary joint provided on the shaft portion of each polishing roll 10, 11, 12 on the side opposite to the drive motor side, through which water or a heat medium is circulated in order to control the surface temperature of each polishing roll 10, 11, 12. It is something that makes you

In order to manufacture a product using the above plastic sheet manufacturing apparatus, the supplied plastic raw material is melted and plasticized in the extruder 1, and then expelled from the T-die 2 in the form of a sheet. The sheet in the molten state is 3
The book is compressed between book polishing rolls 10, 11, and 12 and simultaneously cooled and solidified, passes through a take-up machine 4, and is cut into a predetermined size by a cutter 5 to become a product.

At this time, each of the polishing rolls 10-12 and the lower take-up roll 13 are driven by independent drive motors 15-18 via respective worm reducers 19-22, as shown in FIG.

By the way, there are several problems when cooling and solidifying molten resin and forming it into a sheet.A representative example is the horizontal striped pattern that appears on the sheet surface at right angles to the discharge direction, and this is generally a gear mark. This is what is called. Other appearance problems that occur during the cooling process in the polishing stand 3 include bank marks that resemble gear marks, adhesive marks, and shrinkage distortion, but these can be resolved by carefully setting the molding conditions. It is something that can be resolved.

However, it is difficult to eliminate the gear mark, and this is considered to be a major problem, especially when it comes to transparent sheets. Transparent sheets are often used for the same purpose as glass, so if the gear mark is strong, the image seen through the sheet will be distorted, significantly weakening the perspective effect, impairing the essential transparency, and reducing the product value. Or the added value will drop significantly.

The occurrence of gear marks is essentially due to the adoption of a gear reduction mechanism as a means for driving the polishing rolls 10 to 12 of the polishing stand 3, and as long as a gear mechanism is used in this way, gear marks can hardly be eliminated. It's impossible.

For example, when a single-stage worm reducer is used as the gear reduction mechanism, the gear mark is
A combination of short-period gear marks caused by rotation and long-period gear marks caused by one revolution of the worm wheel appears on the sheet surface.

Polishing stand 3 shown in Figures 4 and 7
The structure of the drive unit is said to have the least number of gear marks among those on the market, but it is still not completely free of gear marks.

(Problems to be Solved by the Invention) As described above, when a plastic sheet is formed using a polishing stand that employs a conventional gear-based speed reduction mechanism, there is a problem in that gear marks cannot be avoided.

The present invention was made with the aim of eliminating this gear mark, and is intended to provide a polishing stand that employs a transmission mechanism that does not cause bumps.

(Means for Solving the Problems) Therefore, the present invention provides a polishing stand for a plastic sheet manufacturing apparatus, including a drive motor that independently drives each polishing roll of a group of polishing rolls built into the polishing stand, and a drive motor that independently drives each polishing roll of a polishing roll group built into the polishing stand. The present invention is configured to include a planetary roller speed reducer that is connected in series with a drive motor and has no backlash, and is used as a means for solving the above-mentioned problems.

(Function) By adopting a planetary roller reducer in the polishing roll drive system, it is possible to drastically reduce rotational unevenness of each roll, and as a result, the appearance of gear marks on the formed sheet surface is minimized. It's stopped.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG.

FIG. 1 is a drive system diagram of a polishing stand and a take-off machine showing an embodiment of the present invention. Note that the parts using the same reference numbers as those in the conventional device shown in FIG. 7 in the figure are the same parts as in the conventional device, so the differences from the conventional device will be explained here.

In the figure, numerals 30, 31, 32, and 33 indicate planetary roller speed reducers, which are commercially available planetary roller type speed reducers that transmit power without backlash. These planetary roller reducers 30,
Reference numerals 31, 32, and 33 denote drive motors 15, 16, and 1 that independently drive the polishing rolls 10, 11, and 12 in the upper, middle, and lower stages, and the lower take-up roll 13, respectively.
7, 18 and the respective rolls, connecting the three in series. A shaft joint 34 with no uneven rotation is used for this connection.

The operation of this embodiment employing such a configuration will be explained.

Upper, middle and lower polishing rolls 10, 11, 1
2 and the lower take-up roll 13 are connected to respective drive motors 15, 16, 17, 18 via respective planetary roller reducers 30, 31, 32, 33 and shaft couplings 34.
It is driven by extremely reducing uneven rotation.

The cause of gear marks or thickness unevenness on sheet molded products is said to be due to the rotation accuracy of the gear reducer in the drive system of each roll, angular velocity fluctuation rate, backlash vibration, etc. Among these, angular velocity fluctuation rate is the main cause of gear mark occurrence. It is said that

Therefore, an experiment was conducted to compare the amount of angular velocity variation in the conventional worm reducer and the amount of angular velocity variation in the planetary roller reducer used in this embodiment.

Figure 2 shows the results, and as is clear from the figure, the angular velocity variation Δω ₁ of the planetary roller reducer is 1/ of the angular velocity variation Δω ₂ of the worm reducer.
It turns out that it is possible to reduce the number to 10 or less.

(Effects of the invention) As explained in detail above, the present invention is equipped with a planetary roller reducer with no backlash, which is connected in series with a motor that drives each polishing roll independently. By using it for rolls, it has the effect of improving rotation accuracy and completely eliminating gear marks that occur in conventional gear reducers.

[Brief explanation of drawings]

Fig. 1 is a drive system diagram of a polishing stand and take-off machine showing an embodiment of the present invention, Fig. 2 is an oscilloscope showing an example of measured waveforms of rotation accuracy in a worm reducer and a planetary roller reducer, and Fig. 3 is a plastic Figure 4 is a side view of the layout of the sheet manufacturing device; Figure 4 is a side view of a conventional polishing stand and take-up machine;
The drawings are a view taken in the direction of arrow A in FIG. 4, FIG. 6 is a cross-sectional view of a molded portion of a plastic sheet, and FIG. 7 is a drive system diagram of a conventional polishing stand and take-off machine. Explanation of the main parts of the figure, 10, 11, 12...polishing roll, 13...lower take-up roll, 1
5, 16, 17, 18... Drive motor, 30, 3
1, 32, 33... Planetary roller reducer.

Claims (1)

[Scope of utility model registration request] In a polishing stand of a plastic sheet manufacturing device, a drive motor independently drives each polishing roll of a group of polishing rolls built into the polishing stand, and a planetary roller reduction gear with no backlash that connects each roll and the drive motor in series. A polishing stand for plastic sheet manufacturing equipment, characterized by comprising: