JPS62204918A - Plasticization of plastic, rubber or the like and similar device therefor - Google Patents

Abstract

PURPOSE:To obtain a general-purpose machine, capable of coping with various materials and uses by one set of the machine, by a method wherein material supplying holes are provided at two places in the lengthwise direction of a cylinder and the hole at the downstream side of resin is permitted to be blockaded while the internal pressure of the cylinder at said hole can be increased to a set pressure. CONSTITUTION:A single shaft extruder is provided with three sets of holes capable of supplying materials while the material supplying holes (a), (b), (c) are arranged sequentially from the base of a screw 1. In case a material is supplied from the supplying hole (b), the supplying hole (c) is blockaded by a plug 6 and the cylinder is constituted so as to be capable of generating the same pressure as a normal cylinder. The supplying hole (a) at the upstream side is provided with a cover 7 only. When a frictional force between resin and the cylinder 2 is small, the supplying capacity of the resin is small, a discharging amount is very small or the variability or fluctuation of the discharging amount is generated, the material is supplied through the supplying hole (a) nearest to the base end of the cylinder and remaining supplying holes (b), (c) are blockaded by the plugs 6. In a reverse case, the material is supplied through the supplying hole (c) and other supplying holes (a), (b), are closed by the cover 7 so that foreign materials will never invade into the cylinder.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is applicable to injection molding machines, extrusion machines, plasticizing equipment for plastics, rubber, etc. It is related to the device.

(Prior Art) A typical configuration of a conventional plasticizing device for plastics, rubber, etc. is shown in FIG. Conventional devices basically have one raw material supply hole a. As a special example, in an extruder that mixes long fibers such as glass fibers with plastic, as shown in Figure 5, the screw base is The solid phase resin introduced from the mouth is once plasticized and melted.
In addition, there is a method in which a part is created in which the pressure of the molten resin is reduced to approximately normal pressure, and a hole i is provided in this part for supplying another long fiber.

In both figures, 1 is a screw, 2 is a cylinder, 3 is a heater attached to the outer periphery of the cylinder, 4 is a raw material supply hopper, and 5 is a speed reducer for driving the screw.

By the way, in recent years, in the field of plastic processing, with the diversification of raw materials and applications, the conventional specialized processing machines for certain types and specific applications have been replaced by highly versatile molding machines that can be applied to a large number of raw materials and applications with one machine. The demands are changing.

Plastic raw materials vary widely; for example, the melting point ranges from around 100°C to around 300°C, and the melt viscosity ranges from the order of 100 poise to 100,000 poise.
There are a wide variety of resins, up to the order of It is extremely difficult to satisfy the demand for greatly expanding the range of raw materials and uses as described above using equipment.

One major problem with versatility is that the ability to supply phase resin varies greatly depending on the raw material.

In other words, (11) for raw materials with small frictional force with the metal surface, the screw feed portion which is the solid phase resin transport portion (see Figure 4)
or by machining a concave groove (commonly known as a group) (groove as shown in Fig. 2 8) on the inner surface of the cylinder just below the raw material supply hole.
By increasing the coefficient of friction between the cylinder and the resin, the resin supply capacity is expanded and the discharge amount of the screw is increased. However, on the contrary (2) for raw materials such as PC resin that have a large frictional force with metal surfaces, the above-mentioned measures adopted for raw materials with a small friction coefficient as in item (1) will abnormally increase the resin supply capacity. As a result, the discharge amount was too large, resulting in poor homogeneity of the plasticized resin, and the screw driving torque became abnormally large.

Here, the above frictional force refers to the viscous shear force that acts between the solid resin and the cylinder when the resin melts by forming a thin melt fill on the inner surface of the cylinder, and refers to the viscous shear force that acts between the solid resin and the metal surface. Similar to friction, this is called frictional force.

Also, similar to the above problem regarding the magnitude of the friction coefficient between the metal surface and the resin, the Fg between the resin particles! Friction force, resin deformation resistance,
Even when trying to plasticize raw materials with large energy differences required for plasticization using the same device, the screw drive torque for raw materials with large values of these values may be more than twice that of raw materials with small values.

In this way, when trying to plasticize raw materials with significantly different physical properties using the same plasticizing equipment, the machine specifications are increased so that it can be applied to some special resins (for example, resins with large driving torque). It is necessary to keep it. Alternatively, an optimal mechanical device may be created based on a raw material with certain physical properties, and some performance may be unavoidably sacrificed for raw materials with other physical properties.

One measure taken to deal with this problem is to install a quantitative feeder connected to the plasticizing device, which can supply an amount of raw material depending on the raw material characteristics.

Although this method can relatively easily solve the above-mentioned problems, it has drawbacks such as increased equipment costs and increased maintenance work for the machine due to the increased number of mechanical elements to be operated.

In addition, the plasticizing device for mixing long fibers, which has two raw material supply holes as shown in Fig. 5 as a conventional example, is designed to solve the above-mentioned problems related to solid phase resin feeding and resin melting. Rather, the idea is to supply different raw materials through separate raw material supply holes, and to effectively mix and supply the two.

Therefore, although this plasticizing device for mixing long fibers has a plurality of raw material supply holes, each raw material supply hole is always open.

(Problems to be Solved by the Invention) As described above, in the conventional plasticizing apparatus of this type, since the cylinder is provided with only one raw material supply hole, raw materials with different physical properties can be fed into one machine. Even if you try to plasticize everything optimally using a machine like this, it is impossible, and other factors are added to the demand for versatility, making it difficult to realize it.

The present invention was developed to solve the various problems mentioned above, and aims to provide a so-called general-purpose machine that can appropriately handle a variety of raw materials and uses with one machine.

(Means for Solving the Problems) Therefore, the present invention provides a system for plasticizing plastics, rubber, etc., which is composed of an axle or a multi-shaft screw, and similar devices thereof.
Two or more raw material supply holes are provided in the longitudinal direction of the cylinder, and a hole on the downstream side of the resin flow among the plurality of raw material supply holes can be closed, and when the hole is closed, the cylinder internal pressure in the hole increases to a set pressure. The present invention is designed to enable the above-mentioned problems, and is intended to solve the above-mentioned problems.

(Function) The cylinder is equipped with multiple raw material supply holes that can supply raw materials,
By making it possible to select the position of the feed hole depending on the physical properties of the raw material, the feeding capacity of the raw material resin and the actual length of the plasticizing section can be changed, making it versatile for plasticizing, cross-circuiting, etc. for raw materials with various characteristics. It has a sexuality.

Therefore, among the holes that can supply multiple raw materials, those on the downstream side in terms of resin flow are plugged and completely sealed, compared to the supply holes that actually supply raw materials. It makes it possible to set the cylinder internal pressure in the hole to the set pressure, and performs the same function as a normal cylinder.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The present invention is a technology that can be applied to single-screw or multi-screw plasticizing devices in which the screw moves backward, and to extruders that do not have a screw backward movement, and is also applicable to extrusion machines for mixing and cross-tracking in food processing machines. Although this technology can also be applied to extruders, a single-screw extruder will be described here as a typical example.

Figure 1 shows an embodiment of the present invention, with three holes through which raw materials can be supplied.
This figure shows a single-screw extruder. These raw material supply holes are indicated by symbols a, b, and c in order from the base of the screw 1. In Fig. 1, the raw material is supplied from the supply hole located in the middle when viewed in the longitudinal direction of the screw, and all of these supply holes The screw tip side supply hole C on the downstream side in terms of resin flow is blocked by a plug 6, and the structure is such that the same pressure as a normal cylinder can be generated in the cylinder 2 at this part. There is. Regarding the supply hole a on the upstream side, since the raw resin does not pass through this part, there is no need to maintain the internal pressure of the cylinder, and a simple cover 7 is provided to prevent foreign matter from falling from this hole. It's just that.

If the friction force between the resin and the cylinder 2 is small, the resin supply capacity is small, the discharge amount is very small, or there are variations or fluctuations in the discharge amount, the raw material should be supplied from the base end of the cylinder. The supply hole A closest to the cylinder 2 is used, and the remaining supply holes G and C are each closed with a plug 6 so that the internal pressure of the cylinder 2 can be maintained. Also, the resin supply capacity is too strong and the screw drive torque becomes abnormally large.
If the discharge amount is large but the uniformity is poor, feed the raw material from the supply hole C on the screw tip side, and cover the other two supply holes a and b to which no raw material is supplied with a cover 7 to prevent foreign matter from entering. and use it.

Figure 2 shows three supply holes a that can supply raw materials, similar to Figure 1.
, b, and c, but the shape of the inner surface of the cylinder 2 corresponding to each material supply hole a, b, and c is different, and the shape of the inner surface of the cylinder 2 corresponding to each raw material supply hole a, b, and c is different from that shown in FIG. 3 (A
), the supply hole part has a shallow and narrow groove 2b as shown in Figure 3 (B), and the supply hole C part has a groove 2b as shown in Figure 3 (C). As shown in the figure, the structure is a combination of ordinary cylindrical cylinders. In the extruder shown in Figure 1, by changing the length of the raw material supply section (feed section), an attempt was made to expand the range of operable conditions for raw materials exhibiting different frictional force behaviors. The device shown in the figure can be operated even further by not only increasing the length of the feed section, but also by combining cylinders with different groups (concave grooves) on the inside that have a stronger material pushing ability. This is an attempt to expand the range of conditions. In the device according to the present invention having a large number of supply holes capable of supplying raw materials,
The same idea can be used to change the screw length of the actual plasticized part that forms the molten layer of resin on the inner surface of the cylinder. It is also possible to adjust the resin pressure inside the cylinder.

Note that although the shapes shown in FIGS. 3A, 3B, and 3C are examples of the shape of the inner surface of the cylinder shown in FIG.
The shape of this inner surface is not limited to the above shape, but may be formed into another shape, for example, a polygon.

(Effects of the Invention) As described above in detail, according to the present invention, solid phase raw materials can be fed with one machine in plasticizing various types of plastics and rubbers having different physical properties, or in similar equipment. Abnormal increase in torque due to excessive feed capacity, discharge of heterogeneous material, discharge fluctuation due to insufficient feed capacity, and decrease in discharge amount due to dissimilar raw materials, whose capacity can be easily adjusted. In addition, it is possible to obtain a plasticizing or similar device with a relatively simple structure, low cost, and versatility.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a plastic extruder as an embodiment of the present invention, Fig. 2 is a side sectional view of the same extruder showing another embodiment of the invention, and Figs. 3 (A) and (B). (C) is an AA, BB, and CC sectional view of each raw material supply hole in Figure 2;
The figure is a side sectional view of an extruder which is a conventional example with one raw material supply hole, and Figure 5 is the same. FIG. Explanation of the main parts of the diagram 1 - Screw 2 - Cylinder 2a, 2b - Groove 4 - Raw material supply hopper a, b, c - (raw material supply) hole 6 - Plug 7 - Cover

Claims (1)

[Claims] In plasticizing and similar equipment for plastics, rubber, etc., consisting of a single shaft or multi-screw, two or more raw material supply holes are provided along the longitudinal direction of the cylinder, and one of the plurality of raw material supply holes is located downstream of the resin flow. A device for plasticizing plastics, rubber, etc. and similar devices, characterized in that the hole in the hole can be closed, and when the hole is closed, the internal pressure of the cylinder in the hole can be increased to a set pressure.