JPS61209126A - Blow molding - Google Patents

Abstract

PURPOSE:To obtain a hollow body with no foreign matter by a method wherein laser beams are irradiated to transmit a preformed body or intermediate formed body. CONSTITUTION:A corrugation type blow molding machine 4 moves like caterpillars so as to successively clamp mold by positioning a tubular thermoplastic preformed body 41 between split molds 42a and 42b, both of which repeat their opening and closing. The tubular preformed body 41 is formed into a hollow formed body by jetting pressure fluid in its interior, and cooled down. After that, the pressure fluid in the interior of the resultant intermediate formed body (c) is discharged and said split molds 42a and 42b are open in order to obtain the intermediate formed bodies (c) connected with one another by flashes (d) or surplus portions. During the course of the intermediate formed body (c) in front of a laser detector 6, laser beams repeatedly traverse the surface of the intermediate formed body (c) in the direction normal to the direction of movement of the body (c) by the action of vibrating mirrors. In order to detect foreign mattes or the like, two laser beams are irradiated to the intermediate formed body (c) from the directions intersecting at right angles by means of two laser beam projectors 61 and 61, two vibrating mirrors 62 and 62 and two laser beam receives 63 and 63.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blow molding method for obtaining hollow bodies such as blow bottles for foods, medicines, etc. or tanks for various liquids, and more specifically relates to a method for forming hollow bodies such as blow bottles for foods, medicines, etc. or tanks for various liquids.

The present invention relates to a blow molding method for obtaining a hollow body free of undissolved matter, burnt material, carbonization, stains, etc.

[Conventional technology]

Conventionally, in the hollow molding method to obtain a hollow body free of the above-mentioned foreign objects, the above-mentioned foreign objects are detected with the naked eye after the hollow body is formed, but such work can cause eye strain for the operator if it continues for a long time. This method has the disadvantage of increasing the number of detection errors, and there is also a limit to the throughput of visual detection by humans, so high-speed inspection cannot be expected. In view of the labor and inaccuracy of visual inspection, it has been proposed to use a television camera instead of the human eye.

In addition, the technology for detecting foreign objects using a television camera is disclosed in Japanese Patent Application Laid-Open No. 55-50144, and Japanese Patent Application Laid-Open No. 59-314.
This is shown in Publication No. 37.

[Problem that the invention seeks to solve]

By the way, when analyzing images using a television camera, it is necessary to stop the subject while the shutter of the television camera is open. Generally, a television camera takes 16.7 milliseconds to form one screen, so unless the subject is stopped for at least this time, the image data obtained during this time will be inaccurate. Therefore, in the former technique mentioned above, when the hollow object that is the subject passes in front of the TV camera, the movement of the hollow object itself is stopped mechanically, or the image of the hollow object is stopped optically using a strobe. There are, but
When transporting a hollow body is stopped mechanically, the transport method is extremely complicated and intermittent transport at high speed is virtually impossible.Also, when stopping optically using a strobe, malfunctions due to the light from the strobe may occur. This has the disadvantage that the accuracy decreases.

Furthermore, the latter technique has a drawback in that there is a limit to the size of foreign matter or undissolved matter that can be detected by a television camera, and that foreign matter of a size actually required for molding cannot be detected.

The parison, which is a preform before blow molding, turns into a very large foreign object when it is molded and appears on the surface of the hollow body, so even if it is a small foreign object or is not melted, it becomes a very large object when it is formed and appears on the surface of the hollow body. Therefore, it is necessary to detect more precise objects than detecting the hollow body. However, television cameras have the disadvantage that they cannot be detected.

[Means and effects for solving the problems] The present invention was made in view of the above-mentioned problems, and consists of disposing a preformed body of thermoplastic synthetic resin between molds, and then tightening the mold to remove the preform. In the method of blow molding a hollow body, an intermediate molded body is formed by injecting pressure fluid into the body, and the surplus portion of this hollow molded body is cut off to obtain a hollow body. The gist of this method is a hollow forming method that detects and ejects foreign matter from the hollow body by changing the energy of the transmitted laser, thereby obtaining a hollow body free of foreign matter.By using a laser with a small beam diameter, , extremely minute foreign matter, undissolved matter, scorch, carbonization, dirt, etc. can be detected accurately, and the laser is applied directly to preforms or intermediate molds that are continuously placed under constant conditions. These preforms or intermediate molds can be easily detected continuously without any positional restriction.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

In the figure, 1 is a rotary blow molding machine which is an example of a continuous blow molding machine for molding the intermediate molded product a, and 2 is a surplus portion of the intermediate molded product a, which is disposed adjacent to the rotary blow molding machine 1. A burr removing machine 3 is a conveying machine that conveys the hollow body a from which the burrs b have been removed.

The rotary blow molding machine 1 is a known device, and a main body 10 is attached to the outer periphery of a rotating disk 11 that rotates around a rotating shaft 12.
Multiple sets of split molds 1 consisting of a and a lid 10b that opens and closes
0 is attached facing the rotation direction of the rotating disk 11,
The lid body 10b rotates as the rotating disk 11 rotates.
The tubular preform 15 supplied into the split mold IO is sandwiched between the closed lids at the terminal end of the open lid section, and is hollow-molded in this closed lid section.
The intermediate molded body a is taken out at the starting end of the lid-opening section. At this time, the intermediate molded bodies a are connected by burrs b and are taken out in a continuous state.

The tubular preform 15 supplied into the split mold 10 is obtained by extruding a thermoplastic synthetic resin kneaded and melted in an extruder (not shown) into a tubular shape through an extruder 14. He-
It has a laser projector 16 that projects a laser generated by Ne gas, and the laser generated by the laser projector 16 is reflected by a vibrating mirror 17 and enters the tubular preform 15. After passing through the tubular preform 15, it is arranged so as to advance to a light receiver 18 fixed above the main body 10a by suitable means. This vibrating mirror 17 changes its direction by a minute angle while maintaining the incident angle of the laser, so that the laser penetrating into the tubular preform 15 is oriented relative to the longitudinal direction of the tubular preform 15. The laser returns to its original state by scanning in a transverse manner and shaking the vibrating mirror 17, and this is repeated by vibrating the vibrating mirror 17. The vibrating mirror 17 can be vibrated at high speed by a known method such as using magnetic force.

The burr removing machine 2 is disposed adjacent to the intermediate molded body take-out section of the rotary blow molding machine 1, and is connected to the drive section 23.
The rotational power is transmitted to a rotating disc through a rotating shaft 22, and a separation mold 20 for separating and removing the hollow body a° and the burr b is installed on the outer peripheral surface of this rotating disc as one of the split molds 10 of the rotary blow molding machine l. The mounting is done at the same pitch.

The conveyor 3 is disposed adjacent to the discharge part of the hollow body a' of the deburr removal machine 2, and includes a conveyor 30 that receives and conveys the hollow body a' and a conveyor 30 located on the side of this conveyor 30. An ejector 31 having means for ejecting the upper hollow body a from above the conveyor 30, and a phototube 32 located near the upstream side of the conveyor 30 of the ejector 31 to detect the hollow body a passing over the conveyor 30. (See Figures 1 and 2)
.

The molding method of this example will be explained in order.

A transparent or natural-colored tubular preform 15 mainly made of polyethylene is extruded from the extruder 14.

A laser beam generated by He-Ne gas is projected from a laser projector 16 located parallel to the extrusion 14 in parallel to the extrusion direction of the tubular preform 15, and this laser is reflected at right angles by a vibrating mirror 17. , tubular preform 1
Transmit perpendicular to 5.

The laser beam diameter at this time is φ1mm and φ10mm.
It traverses the inside of the tubular body by vibrating the vibrating mirror 17. The beam width of this laser is φlQmm
The thickness is preferably about 12 mm for the tubular preform 15 of . A laser beam having a beam diameter of 1 mm reciprocates between the beam widths of 12 mm in accordance with the vibration of the vibrating mirror 17. The surface of the tubular preform 15 is covered by a laser that is transmitted across the tubular preform 15 which is successively extruded.

At this time, the electrical flow is as shown in FIGS. 2 and 3. As shown in FIGS.
8, amplified by a light receiving amplifier, level setting and a comparator to detect the sensed laser energy, and output this energy as a voltage. At this time, if foreign matter is included in the tubular preform 15, part of the laser is cut off, the output voltage to be sensed decreases, and whether or not it is acceptable is determined by level setting and a comparator.

The tubular preform 15 through which the laser has passed is placed on a split mold on the outer peripheral surface of the rotary disk machine 1 which is rotated at a constant rotational speed by the drive unit 13, and the tubular preform 15 is sequentially clamped. As the rotation progresses, blowing, cooling,
The blown fluid is sequentially discharged, and finally the mold is opened to obtain intermediate molded bodies a connected by burrs b, which are connected to a burr removing machine 2. In paris removal machine 2, intermediate molded body a
The burr b is separated and removed to obtain a hollow body a', which is conveyed to a predetermined position by a conveyor 3. If the tubular preform 15 contains foreign matter, the transmitted laser will be blocked, and the voltage detected by the receiver will decrease. The hollow body a passes in front of the ejector 31 due to the rotational speed from the drive unit 13.23 of the machine 2 and the photocell 32.
A counter analyzes the time delay based on the information on the number of ``,'' and the ejector 31 discharges the hollow body a'' containing foreign matter. In this way, a hollow body free of foreign matter is obtained.

Defects such as foreign matter, undissolved matter, burnt matter, carbide, and dirt are normally contained in the tubular preform 15 in an extremely small state, but with a laser as in this embodiment, the beam diameter is extremely small. Because it is small, even if the foreign matter contained in the tubular preform is too small to be detected visually, it can be accurately detected and the hollow body containing foreign matter can be properly removed, and only the hollow body that does not contain foreign matter can be detected. can be obtained.

Furthermore, even when the tubular preform is extruded to an endless length at high speed as in the rotary blow molding machine of this embodiment, the vibration of the vibrating mirror 17 can be made extremely fast by using magnetism or the like. The entire preform can be effectively penetrated and judged.

FIG. 4 shows another embodiment.

In the figure, 4 is a corrugated blow molding machine for molding the intermediate molded body C, and 5 is a burr installed adjacent to this corrugated blow molding machine to remove burrs d, which are surplus parts of the intermediate molded body C. The remover 6 is a laser detector which is a feature of the present invention.

This laser detector 6 uses a plurality of lasers, and in this embodiment, two laser projectors 61 each.
．． 61, vibrating mirrors 62, 62, and light receivers 63, 63, and the laser projector 61, 61 is provided at an angle of 90'' with respect to the intermediate molded body C.

The flow of this embodiment will be explained in order.

The corrugated blow molding machine 4 moves in a caterpillar shape,
A tubular preformed body 41 of thermoplastic synthetic resin is placed between the divided molds 42a and 42b, which are repeatedly separated and separated, and the molds are successively clamped. The mold-clamped tubular preform 41 is divided into divided molds 42a and 42b by ejecting pressure fluid into its interior.
It is molded into the shape of a hollow molded body formed inside it.

Then, after cooling and releasing the pressure fluid inside the intermediate molded body C, the split molds 42a and 42b are opened to obtain an intermediate molded body C connected at the surplus portion of the burr d. When this intermediate molded body C passes in front of the laser detector 6, the laser beam repeatedly crosses the surface of the intermediate molded body C in the direction perpendicular to the moving direction due to the action of the vibrating mirror, as in the previous embodiment. Together with the movement of the molded body C, the entire intermediate molded body C is traversed. As shown in FIGS. 4 and 5, two laser beams are emitted from two laser projectors 61.61, a vibrating mirror 62.62, and a light receiver 63.63 to the intermediate formed body C from directions orthogonal to each other. Detect foreign objects, etc.

After passing through the laser detector 6 and detecting the presence of foreign objects,
The bar IJ d at both ends of the intermediate molded body C is cut and removed by a deburring machine 5, and the intermediate molded body C is separated one by one to obtain a hollow body C°. When the laser detector 6 detects foreign matter in the intermediate molded body C, the ejector 7 located downstream of the deburr remover 5 in the moving direction discharges the hollow body C' containing the foreign matter. Finish molding.

In this embodiment, since the intermediate molded body C can pass through the laser detector 6 while connected to the burr d, its position can be regulated in a fixed direction without rotation, and even extremely minute foreign objects can be detected. This makes it possible to easily obtain a hollow body that does not contain any foreign matter, even if it is minute. Furthermore, since the intermediate molded bodies C are connected to each other by the burrs d, there is no need to hold the hollow body C with a holding jig (
Even when the hollow body C° is taken out from the blow molding machine, the position of the hollow body C° can be stably maintained, and the laser beam transmitted therethrough can be maintained in that state without any obstruction.

By the way, as shown in FIG. 5, P t Ql, P
The laser that passes through the edges of the intermediate molded body C represented by zQt, P 3Q3, and P a Qa has a longer transmission distance than other parts, so the energy of the laser that disappears is also large, which reduces the possibility of foreign matter generation. The laser energy will be lost to the parts that are missing.

The laser detector 6 determines the presence or absence of foreign matter based on the degree of energy dissipation when passing through the intermediate compact C, and the degree of dissipation is defined by the level setting shown in the block diagram of FIG. , the material, wall thickness, and other conditions of the intermediate molded body C, and the presence or absence of foreign matter is detected by comparing the set level with the energy level of the laser beam that reaches the light receiver. Therefore, the above p, Ql, P
The transmission laser between gQz, P3 Qa, and P4 Qa requires a low setting level for its disappearance, and in order to accurately detect this part, the overall setting level must be lowered, and a very clear Only foreign objects etc. can be detected. Therefore, the laser is transmitted with the width shown by Ql QzQ, Q in Fig. 5, and the above P+ Ql, Pz
By excluding the Qt, P3 Qa, and Pa Qa portions, the above-mentioned drawbacks are eliminated and the set level can be increased, making it possible to sufficiently detect even minute foreign objects. Above P
+ Ql, P2Qt.

The transmitted portions of the lasers, denoted P*Qx and P a Qa, are each complemented by mutual lasers that are at an angle of 90'' to each other.

In the above embodiment, since the intermediate molded body is a mere cylinder, 2
Although several lasers were used, it is preferable to decide the number of lasers to be used depending on the shape of the intermediate molded product or preformed product.

FIG. 6 shows a third embodiment, in which 81 and 81 are divided molds and have blowing means (not shown) in the mold. A heating means 84.84 is provided above the split mold 81.81, and a sheet-like preform 83 is supplied between the heating means 84.84.

At the lower end of this heating means 84, a laser detector consisting of a laser projector 85 and a light receiver 86 is arranged. This laser projector 85 has a mechanism that swings its direction in the horizontal direction, and traverses the sheet-like preform 83 and transmits light across its entire width.

To explain the flow of this embodiment step by step, the sheet-like preform 83 wound into a roll is placed between the heating means 84 by rotating the drum 82. At the stage where the sheet-like preform 83 is heated by the heating means 84.84 to a temperature at which it can be molded, the split mold 81.
The drum 82 is rotated during 81 to supply at a constant speed.

At this time, the presence or absence of foreign matter is detected by a laser detector provided at the lower end of the heating means 84,84. The sheet-like preform 83 in which foreign matter has been detected is cut off by a cutting means (not shown), and only the sheet-like preform without thermal deterioration is subjected to molding, and the divided molds 81 and 81 are closed to complete the sheet-like preform. Pressure fluid is blown between the bodies to form a hollow body.

According to this embodiment, since the light receiver 86 is inserted between the sheet-like preforms 83 and 83 and the laser beam transmitted through only one sheet-like preform is detected, the detection of the sheet-like preform is extremely accurate. Foreign objects and deterioration can be detected. At this time, if the laser detector and the drum are electrically connected and the drum is rotated to replenish the preform in an amount to compensate for the excised part when the cutting means is used, it is stable and economical. A preformed body is obtained which is heated to . In addition, since a laser is used, even if the Schiff-shaped preform is placed rapidly, it can be sufficiently transmitted through the laser, making it possible to reduce the speed of preform placement for detection, and as a result, the sheet This prevents the shaped preform from cooling and solidifying.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to continuously detect foreign matter, undissolved matter, burnt material, carbonization, dirt, etc. on continuously arranged molded products or preformed products without stopping them. In addition, since a laser with a small beam diameter is used, even extremely small foreign objects can be detected, and a hollow body containing almost no foreign objects can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a reverse mold. FIG. 3 shows a first embodiment of the present invention. FIG. 1 is an explanatory diagram showing an apparatus used for implementation, FIG. is the block diagram of the laser detector,
Figures 4 and 5 show the second embodiment, with Figure 4 being an explanatory diagram showing the apparatus used for the implementation, Figure 5 being a side view of the laser detector in Figure 4, and Figure 6 being a side view of the laser detector shown in Figure 4. FIG. 7 is a conceptual diagram for explaining a third embodiment.

Claims (1)

[Claims] After placing a preformed body of thermoplastic synthetic resin between the molds, the molds are tightened and pressurized fluid is blown into the preformed body to form an intermediate molded body, and the surplus portion of the intermediate molded body is cut off to form a hollow body. In the blow molding method for a hollow body, a laser is applied to a preform or an intermediate formed body, and the foreign matter in the hollow body is detected and ejected by changes in the energy of the transmitted laser, thereby forming a hollow body free of foreign matter. Hollow molding method to obtain the body.