JPS61175008A - Apparatus for controlling wall thickness of parison in blow molding machine - Google Patents

Abstract

PURPOSE:To make it possible to control precisely the wall thickness of a parison, by providing a controller for sending a command to a driving apparatus based on a signal from a comparator for comparing a set signal with a signal from a thickness meter for measuring the thickness of a parison extruded from an outlet slit. CONSTITUTION:As plungers 10 are gradually lowered by the operation of an injection cylinder 9, a parison 20 is extruded from a slit 7 between a mandrel 6 and a flexible plate 36. When the parison 20 has been extruded, an air cylinder 23 is actuated to cause a detecting head 22 to abut against the surface of the parison 20 slightly to determine the thickness of the parison 20 by a thickness meter 21, and its signal is sent to a comparator 25 to be compared with a set signal. When there is a difference between the signals compared in the comparator 25, based on it a driving signal is sent to a servo-valve 27 from a controller 26 to cause a control cylinder 37 to operate so that the width of the slit 7 may be corrected through the introduction of a flexible plate 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the wall thickness of a parison in blow molding.

[Conventional technology]

In recent years, many plastic blow-molded products having a flat shape, such as heat collecting plates and pallets for solar water heaters, have been seen. An example of a conventional blow molding apparatus for molding this type of molded product is shown in FIGS. 6 and 7.

In other words, the Rokususon head body (
A nozzle (2) having an opening similar to the hollow part of the head body (1) is attached to the lower end of the head body (1), and a parison control cylinder (31K) is installed above the head body (1). ), a sheet-like passageway (5α) is arranged between the inside of the nozzle (2) and the lower position of the head body (11) and the lower position of the head body (1). the nozzle (2) so as to form a confluence passage (5b) and a flat annular passage (5c) therebetween.
A mandrel (6) extending in the width direction (horizontal direction in FIG. 7) of the opening is attached, and the mandrel (6) is raised and lowered via the mandrel shaft (4) by operating the parison control cylinder (3) to open the passage. (5G) The width of the exit slit (7) at the lower end can be adjusted.

Further, inside the head body (1), the head body (11
Flat partition wall extending in the width direction of the inner hollow part +s) i
8) A mandrel (6) is erected to sandwich the 'ft mandrel shaft (4), and a resin accumulation chamber α9α9 is formed between each of the partition walls (8) and the inner wall of the head body (1); A flat plunger fiI (11) connected to the injection cylinder +91 installed above the head body +11 is vertically slidably inserted into the storage chamber α9α.
is a guide key when the plunger αl slides.

The plunger α1 has a head body (1
) A vertical groove σ having a required length extending in the vertical direction so as to communicate with the resin population 0υ provided on the upper side of the groove 07J, and a distribution groove a′3 in the width direction (horizontal direction) communicating with the lower end of the vertical groove 07J. The outer surface of the distribution groove (I3) is engraved, and the outer surface of the distribution groove (I3) is formed so that the outer surface of the distribution groove (I3) forms a throttle passage α fathom between the outer surface of the distribution groove (I3) and the inner wall of the head body (1). Further, in the opening surface of the nozzle (2), choke bars αI (II) are buried facing each other in the width direction, and each choke bar αQ is connected to the nozzle (2). The configuration is such that each choke bar 09 can move in and out of the flat annular passage (5G) by being connected to a threaded adjustment bolt α9.

Now, by operating the injection cylinder (9), each plunger α0
is raised by the required amount to form a predetermined accumulation chamber αU!9 at the bottom of each plunger 11 (I), and then the extruder (
When the molten resin is extruded from the head body (1), the resin flows through the longitudinal groove α of each plunger α1 and further into the widthwise distribution groove (13). The resin that has flowed into the distribution groove 03 of α1 is further pushed and flows into the accumulation chamber α9, but at this time, the flow rate is adjusted when passing through the throttle passage I, and the flow rate is uniform in the width direction into each accumulation chamber ←9. When the resin in each storage chamber reaches the required amount, operate each injection cylinder (9) to release each plunger a [
lower. Then, due to the pressure, the resin in each accumulation chamber α9 passes through the sheet-like passage (5α), the merging passage (5b), and the flat annular passage (5G), and becomes flat annular before being pushed out from the outlet slit (7). It is forcibly extruded as a part integrated with the material.

Then, the extruded parison wire is sandwiched between molds and blow molded.

[Problem that the invention seeks to solve]

However, in the conventional blow molding apparatus described above, the flow rate of the resin is adjusted by operating the adjustment bolt α1 to move each choke bar αa into and out of the flat annular passage (5G), thereby achieving uniformity in the circumferential direction. Although it is possible to obtain high-precision flat-shaped products,
There was no means for accurately controlling the thickness of the parison.

The present invention makes it possible to control the thickness of the parison in the longitudinal direction with high precision.

[Means for solving problems]

In the present invention, a hollow flat nozzle is attached to the lower end of a parison head body equipped with a flat plate plunger, and a mandrel is disposed within the nozzle to form an exit slit between the mandrel and the nozzle. A required recess is provided in the inner corner of the lower end of the nozzle, and in the recess,
In a blow molding device, a slit width adjusting flexible plate is attached to adjust the width of the exit slit, and the flexible plate can be operated by a drive device, and the wall thickness of the parison extruded from the exit slit is A configuration comprising: a thickness gauge that measures the thickness, a comparator that compares a signal from the thickness gauge with a setting signal, and a controller that sends a command to the drive device based on the signal from the comparator. has.

[For production]

Therefore, the measured parison thickness is compared with a set value and the width of the exit slit is controlled based on that value.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. 1st.
Figure 3.4 shows an embodiment of the present invention. In Figure 1, (2υ is an ultrasonic thickness gage for measuring the thickness of the parison, which is held by an air cylinder (c) and connected to a slit (c). The signal from the detection head disposed at the outlet of 7) can be processed and displayed on, for example, a digital display 24). (C) is a comparator that compares the signal from the thickness gauge Qυ and the setting signal from the controller (A);
The signal obtained from the comparison is sent to the controller (a). The controller (a) drives a servo valve based on the signal from the comparator, and is capable of operating the control cylinder 67). In addition, the control cylinder C37) and the injection cylinder (9) are each equipped with a position detector f.
IC31 is provided, and a detection signal is sent to the controller (to). (To) in Figure 1 is Air Units),
C31) indicates a hydraulic unit.

As shown in FIGS. 2(A) and 2(B), the thickness gauge measures the time between the echo S reflected on the surface of the object to be measured (in this case, the parison) and the echo B1 reflected on the back surface of the object to be measured. Measure T, multiply by 1/2 as a one-way value, further multiply by the preset sound speed value V of the object to be measured, and calculate the thickness D by D:= T
It is calculated as x 1/2 x V. αD is a transducer and 10υ is a delay member.

In FIG. 1, the same reference numerals as in FIG. 6 indicate the same parts.

In such a configuration, when each plunger Ql gradually descends due to the operation of the injection cylinder (9), the mandrel (6
) and the flexible plate (7), the parison is extruded from the slit (7). When the parison ■ is pushed out, operate the air cylinder (c) to move the detection head @ to the parison (
) Lightly touch the surface and measure the thickness of the parison with a thickness gauge Q.
υ is obtained, and the signal is sent to the comparator (c) and compared with the setting signal. Note that this setting signal corresponds to the position of the flexible plate (to) and the plunger α1 detected by the detector @c31. If there is a difference in the signals compared by the comparator (c), a drive signal is sent from the controller (2) to the servo valve (5) based on that signal, and the control cylinder c3η is actuated. The width of the slit (7) is adjusted by moving the flexible plate in and out.

In the blow molding equipment shown in the conventional example, if the shape of the molded product has irregularities, the parison control in the vertical direction by raising and lowering the mandrel (6) alone cannot correspond to the shape and control within the cross section cannot be achieved. In this embodiment, the thickness of the parison in the cross-sectional direction can be changed arbitrarily in accordance with the uneven shape of the molded product, and the thickness can also be controlled with high precision. be.

That is, as shown in Fig. 5, a convex portion (
), the wall thickness of the molded product r33 becomes thinner, so in order to compensate for the wall thickness, when the mandrel (6) is lowered, all parts in the same circumferential direction, including the part indicated by (to) on the opposite side, are On the other hand, if there is a recess in a part of the molded product 33, the wall thickness of the molded product 32 will increase, so in order to reduce the wall thickness, the mandrel (6) is raised. However, contrary to the above, there was a problem in that the entire wall thickness in the same circumferential direction including the portion indicated by (b) on the opposite side became thinner.

In the present invention, in the blow molding apparatus shown in FIG. A slit width adjustment flexible plate (to) for adjusting the width of the exit slit (7) is attached to the nozzle (2).
A hydraulic cylinder c37) is installed on the outer side of the cylinder, and its rond is connected to the back surface of the flexible plate through the nozzle (2).

To attach the flexible plate, as shown in detail in FIG.
6a) is inserted from the axial direction into the correspondingly shaped nozzle (2) side, so that the flexible plate (to) can move freely by sliding between the shaft part (36α) and the nozzle (2) side. It's Nishide.

In addition, in FIG. 1.3.4, the same reference numerals as in FIG. 6 indicate the same parts. However, the thickness gauge Qυ and its detection head (2
) are arranged in parallel corresponding to the number of cylinders C371 shown in FIG.

Now, when the servo valve f41 is driven by a command from the controller (A) and the cylinder t3D is actuated to cause each rond (to) to move in and out by a controlled stroke, the flexible plate (t)
is pushed or pulled, widening or narrowing the width of the exit slit (7). This control is performed using the flexible plate (
) to the desired position.

Therefore, the flat annular parison (1) has an outlet slit (the wider the width of the force, the thicker the width, and the narrower the width of the force, the thinner it becomes.) Not only the direction but also the thickness in the cross-sectional direction of the flat annular parison can be freely controlled.In addition, by using this together with the vertical parison control by vertical movement of the mandrel (6), Further, it becomes possible to carry out more detailed control.In addition to the above-mentioned blow molding apparatus that molds the flat annular parison, the present invention can also be applied to a blow molding apparatus that controls the thickness of the annular parison in the cross-sectional direction. It is possible to implement it.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied not only to single-layer but also to multi-layer blow molding machines such as two-layer, three-layer, etc., and other gist of the present invention. Of course, various changes can be made without departing from the above.

[Effects of the Invention] As explained above, according to the wall thickness control device for the blow molding apparatus of the present invention, the slit width is controlled based on the signal from the thickness gauge, so that the longitudinal direction of the parison is controlled. 0, which has the excellent effect of being able to control the wall thickness with high precision.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the parison wall thickness control device in the blow molding apparatus of the present invention, and Fig. 2 shows the measurement principle of the ultrasonic thickness meter. B) is a diagram showing the echo, Figure 3 is a view from the ■-■ arrow in Figure 1, and Figure 4 is a diagram showing the echo.
The figure is a partially enlarged view of Fig. 1, Fig. 5 is an explanatory diagram of a conventional molded product, Fig. 6 is an explanatory diagram of a conventional blow molding device, and Fig. 7 is a view taken along the ■-■ arrow in Fig. 6. be. (1) 7d head body, (2) nozzle, (3) parison control cylinder, (6) mandrel, (7
) is the exit slit, (21) is the ultrasonic thickness gauge, (to) is the comparator, (a) is the controller, (to) is the recess, (to) is the flexible plate, and 0η is the cylinder.

Claims (1)

[Claims] 1) A hollow flat nozzle is attached to the lower end of a parison head body having a flat plate plunger, and a mandrel is disposed within the nozzle to form an exit slit between the mandrel and the nozzle, and the nozzle A required recess is provided in the inner corner of the lower end, a flexible plate for adjusting the width of the exit slit is attached to the recess, and the flexible plate is driven by one or more driving devices. one or more thickness gauges for measuring the wall thickness of the parison extruded from the exit slit, and comparing the signal from the thickness gauge with a set signal; A parison wall thickness control device in a blow molding apparatus, comprising a comparator and a controller that sends a command to the drive device based on a signal from the comparator.