JPH0371011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting pinholes in blow-molded containers.

[Prior Art] The wall thickness of blow-molded containers such as plastic bottles has become thinner with advances in blow-molding technology. For this reason, the incidence of pinholes in molded products is also increasing. As a result, the conventional pinhole inspection after taking out the molded product has become indispensable.

[Problems to be Solved by the Invention] However, in the conventional pinhole inspection, the molded product is once taken out of the mold and is performed off-line, so there is a problem that productivity is significantly reduced. Furthermore, since a place for pinhole inspection and independent equipment for inspection are required, there are problems in that space cannot be used effectively and it is extremely uneconomical.

The present invention has been made in view of the above, and provides a pin for blow-molded containers that allows pinhole inspection of molded products to be performed in-line, thereby improving the effective use of production line space and improving productivity and economic efficiency. A hole detection method is provided.

[Means for Solving the Problems] The present invention provides a molded product having a predetermined shape by inserting a parison extruded from a die head into a mold and blowing gas into the parison in a sealed state from a predetermined gas blowing nozzle. When the mold is opened, a pressure sensor built into the gas blowing nozzle is inserted into the hollow part of the molded product to measure the internal pressure, and this measured value is compared with a reference value. This is a pinhole detection method for blow-molded containers that detects the presence or absence of holes.

Here, the molded products to be inspected by the present invention are:
Any material may be used as long as it can be molded by blow molding.

Moreover, any type of blow molding such as rotary blow molding may be used.

Further, the reference value is the pressure value in the hollow part of a complete product without any pinholes.

Any pressure sensor may be used as long as it can be easily moved in and out of the molded product from the gas blowing nozzle and can detect pressure changes due to gas leakage from pinholes.

Further, it is preferable that the gas supplied from the gas blowing nozzle into the parison is appropriately set to air or the like depending on the properties of the molded product.

[Operation] According to the method for detecting pinholes in a blow-molded container according to the present invention, when the molded product is removed from the mold, a pressure sensor built in the gas blowing nozzle is inserted into the hollow part of the molded product to measure the internal pressure. By comparing this measured value with a reference value, the molded product is inspected for pinholes in-line. As a result, it is possible to effectively utilize production line space and improve productivity and economy.

[Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of an embodiment in which the method of the present invention is applied to pinhole inspection of a product molded with a rotary blow mold. In the figure, reference numeral 1 denotes an extruder that supplies a parison 2, which is the basis of a product to be molded by blow molding, to a mold 4 via a die head 3. The mold 4 includes a mold clamping part 5 that engages the parison 2 into the mold 4, a blow molding start part 7 that blows air, for example, into the parison 2 by a gas blowing nozzle 6 (described later), and a molded product. A plurality of them are arranged on a wheel so as to rotate continuously at predetermined intervals so that they successively pass through a take-out part 8 to be taken out from the mold 4 and return to the mold clamp part 5 again. As shown in FIG. 2, the gas blowing nozzle 6 is attached to the tip of an air cylinder 11 that is connected to an air supply source (not shown) via an air supply pipe 9 and a supply valve 10 in that order. As shown in FIG. 3, the interior of the gas blowing nozzle 6 is comprised of an air supply path 12 for supplying air and a movement path 14 for the pressure sensor 13. Travel route 1
A pressure sensor 13 is attached to a cylinder 15 and is provided inside the cylinder 4 so as to be freely accessible.

First, the extruder 1 is driven to feed the parison 2 from the die head 3 into the mold 4 in the mold clamping section 5. Next, when this mold 4 reaches the blow molding start section 7, the tip of the gas blowing nozzle 6 described above is inserted into the parison 2, and the mold 2 is closed and sealed to allow air to flow from the air supply path 12. is supplied and blow molding is performed. When the mold 4 containing the blow-molded product reaches the take-out part 8, the mold 4 is opened and the product is taken out. When the mold 4 is opened, the cylinder 15 is driven and the gas is The pressure sensor 13 is inserted into the hollow part of the product from the movement path 14 of the blowing nozzle 6. Next, the pressure sensor 13
to measure the pressure inside the product. That is, since the mold 2 is open, if a pinhole is generated in the product, the pressure measured by the pressure sensor 13 does not reach a predetermined value. Therefore, when compared with a reference value measured in advance for a perfect product with no pinholes, the pinholes can be easily discovered since they are smaller than the reference value. Moreover, this pinhole detection can be performed in-line just before the product is pulled out from the mold 2. Therefore, there is no need for a separate location and equipment for pinhole detection. As a result, it is possible to effectively utilize production line space and improve productivity and economy.

[Effects of the Invention] As explained above, according to the method for detecting pinholes in blow-molded containers according to the present invention, pinhole inspection of molded products can be performed in-line, resulting in effective use of production line space, productivity, and economy. It is something that can improve your sexuality.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment in which the method of the present invention is applied to pinhole inspection of products molded with a rotary blow mold, Fig. 2 is an explanatory diagram showing the structure of the same pinhole detector, and Fig. 3 FIG. 2 is an explanatory diagram showing the operation of the present invention. DESCRIPTION OF SYMBOLS 1... Extruder, 2... Parison, 3... Die head, 4... Mold, 5... Mold clamping part, 6... Gas blowing nozzle, 7... Blow molding starting part, 8... Taking out part, 9... Air supply pipe, 10... Supply valve, 11...
...Air cylinder, 12...Air supply path, 13...
...Pressure sensor, 14...Movement path, 15...Cylinder.

Claims (1)

[Claims] 1. Insert the parison extruded from the die head into a mold, blow gas into the parison in a sealed state from a predetermined gas blowing nozzle to mold a molded product of a predetermined shape, and when the mold is opened, the Pinhole detection in blow-molded containers involves inserting a pressure sensor built into the gas blowing nozzle into the hollow part of the molded product to measure the internal pressure, and comparing this measured value with a reference value to detect the presence or absence of pinholes. Method.