JPH0639086B2 - Extrusion molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an extruder, and in particular, a ceramic screw and a resin inner barrel having a self-lubricating property are provided to enhance durability and to improve molding material. The present invention relates to an extrusion molding machine that solves the problem of foreign matter being mixed in.

[Prior Art] Conventionally, an extrusion molding machine having a screw kneading and extrusion molding mechanism such as a clay kneading machine or a vacuum kneading extrusion molding machine has been used for extrusion molding of a clay having plasticity such as ceramics. It has been done. The extruder comprises a barrel and a screw inserted in the barrel, and conventionally,
Cast steel, stainless steel, or the like is mainly used as a material for forming the barrel and the screw.

[Problems to be Solved by the Invention] However, in an extruder formed of a metal material,
Insufficient wear resistance is obtained, which necessitates frequent and frequent replacement of components. For this reason, there are problems such as an increase in cost due to equipment replacement, a decrease in production, and instability of molding conditions (for example, the extrusion pressure fluctuates greatly due to old and new machines due to remarkable wear).

Further, there is a problem that iron and other metals due to abrasion are mixed in the extrusion molding material, which deteriorates product quality.

As a measure for improving the wear resistance of the screw, a screw made of ceramic such as high alumina has been applied for a patent by the present applicant (Japanese Patent Application No. 59-2092).
68), which is being put to practical use.

However, with respect to the barrel with a built-in screw, from the viewpoint of pressure resistance and the like, the metal constituting material is predominantly used, and a proposal for an excellent technique for improving the wear resistance of the barrel has not been made yet. The current situation.

[Means for Solving Problems] In view of the above conventional circumstances, the present invention provides an extrusion molding machine that improves the wear resistance of the extrusion molding machine and solves the problem due to wear.

The extrusion molding machine of the present invention is an extrusion molding machine in which a ceramic screw is inserted in a barrel, and the barrel is formed by internally fitting a resin inner barrel having self-lubricating properties into a metal barrel body. The inner barrel is characterized in that the inner wall surface thereof is provided with a groove and / or a ridge extending in the longitudinal direction of the barrel.

[Operation] A resin having a self-lubricating property has a small dynamic friction coefficient with an extrusion molding material and a low contact resistance with the extrusion molding material, and therefore has extremely high wear resistance. Moreover, it is generally excellent in chemical resistance, physiologically harmless, and excellent in impact resistance.

In the extrusion molding machine of the present invention, the inner surface of the barrel that comes into contact with the extrusion molding material is composed of an inner barrel made of a resin having a self-lubricating property, so that the wear resistance of the barrel is improved and the durability is improved. . Therefore, the wear substance hardly mixes into the product due to wear, but even if it mixes into the product, the non-toxicity and the chemical stability of the resin hardly affect the product quality.

Moreover, the inner wall surface of the resin inner barrel is provided with the groove and / or ridge extending in the longitudinal direction thereof, so that the extrusion molding material can be prevented from idling and the material can be favorably advanced. .

That is, since the resin that constitutes the inner barrel has a small dynamic friction coefficient and a small contact resistance with the material, the kneaded material of the extrusion molding material may spin around and the interior of the barrel may not be efficiently advanced. As described above, by providing the concave groove or the convex strip on the inner wall surface of the inner barrel in the longitudinal direction, the kneaded clay can be prevented from idling and the forward movement can be promoted.

Therefore, the pressure resistance against the pressing force during extrusion molding is sufficiently supplemented by the metal barrel body.

Further, in the extruder of the present invention, since the screw is made of ceramic, there is no problem of screw abrasion.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 are views showing an extruder according to an embodiment of the present invention, in which FIG. 1 is a partial sectional view and FIG.
It is sectional drawing which follows the II-II line of a figure.

The barrel of the extrusion molding machine of the present invention comprises a barrel body 1 made of metal and an inner barrel 2 fitted in the barrel body 1 and having a self-lubricating property. 3 is a ceramic screw.

Examples of the self-lubricating resin forming the inner barrel 2 include nylon, fluororesin, polyethylene, and polyacetal resin. In the present invention, M
A soft plastic material such as C nylon or ultra-high molecular weight polyethylene having self-lubricating property with abrasion resistance and extremely small dynamic friction coefficient is preferable, and ultra-high molecular weight polyethylene is most preferable.

On the other hand, as the metal material of the metal barrel body, cast steel or stainless steel which has been conventionally used as a barrel constituent material can be used.

In the present embodiment, the inner barrel 2 is provided with a plurality of recessed grooves 2a (6 in the figure) extending in the barrel longitudinal direction. By providing such a groove 2a, the extrusion molding material can be prevented from idling and the material can be favorably advanced.

That is, since the resin forming the inner barrel 2 has a small coefficient of dynamic friction and a small contact resistance with the material, the kneaded material of the extrusion molding material may spin around and the inside of the barrel may not be efficiently advanced. As described above, by providing the concave groove 2a on the inner wall surface of the inner barrel 2, it is possible to prevent the kneaded clay from idling and to promote the forward movement.

The size of the concave groove 2a is not particularly limited and may be appropriately determined depending on the scale of the extruder, the purpose of use, etc.
For an inner barrel of about 0 mm, a depth of 3 mm,
It is preferable to provide a groove having a width of about 10 mm in the longitudinal direction of the barrel.

In order to prevent the kneaded clay from spinning and to promote the forward movement, it is sufficient that the inner wall surface of the inner barrel 2 is formed with appropriate irregularities, and not only the concave groove 2a as shown in FIG. It may be an extended ridge.

In this embodiment, the ceramic screw 3 includes the shaft portion 3
a and a screw blade 3b protruding from the peripheral surface of the shaft portion 3a. The shaft portion 3a includes a metal shaft center portion and a ceramic outer portion. The screw blades 3b are made of ceramic, and are integrally formed with the ceramic outer portion of the shaft portion 3a.

Incidentally, in the screw, only the screw blade 3b may be made of ceramic and the shaft portion 3a may be made of metal.
Since the peripheral surface of the shaft portion 3a also comes into contact with the raw material and the labor of attaching the screw blades to the shaft portion can be omitted, the outer portion of the shaft portion 3a and the screw blade portion 3b are made of an integral ceramic. It is preferred that this ceramic monolith be bonded to the shaft center portion.

As the ceramic material forming the screw, a sintered body of alumina, zirconia, silicon nitride, or the like, which has high wear resistance, is preferable, but the AlO ₂ O ₃ content is particularly 80% by weight.
The above alumina-based materials are preferable, and particularly, those having an Al ₂ O ₃ content of 85 to 96% by weight, which are excellent in wear resistance and impact resistance, are preferable. If the Al ₂ O ₃ content is less than 80% by weight, wear resistance is poor, and conversely, if the Al ₂ O ₃ content is too high, impact resistance and moldability thereof are difficult.

In addition to Al ₂ O ₃ , SiO ₂ , CaO, MgO, T
It may include various oxides such as iO ₂ and ZrO ₂ that are contained in ordinary oxide sintered bodies. Further, a small amount of nitride or boride may be contained.

This alumina-based sintered body preferably has a water absorption of 1% or less, particularly 0.1% or less. If the water absorption is greater than 1%, the phenomenon of winding of the raw material around the screw surface occurs, which causes heat generation and an extreme deterioration of the extrusion function, which is not preferable.

Hereinafter, experimental examples will be described.

Experimental Example 1 Ultra high molecular weight polyethylene ("New Light" Sakushin Kogyo
Abrasion resistance test was performed on the extrusion molding machine of the present invention equipped with an inner barrel manufactured by Co., Ltd. and having an average molecular weight of 3.5 million or more) and the conventional extrusion molding machine equipped with a SUS304 stainless steel barrel.

That is, α-Al ₂ O ₃ having an average particle diameter of about 35 to 50 μm.
An extruded kneaded material having (calcined alumina) particles as a main component (96% by weight) and having a water content of about 25 to 30% by weight,
Extrusion molding was performed into a tube shape with a diameter of 7 to 10 mmφ under the following operating conditions, and the wear amount (wear thickness) of the barrel of each extrusion molding machine was examined with respect to the amount of the kneaded clay (calculated as the alumina dry powder amount). It was Note that the wear amount is measured at an auger barrel (inner diameter 50) close to the discharge port where the wear amount is maximum.
mmφ) inner surface.

Operating conditions Auger screw rotation speed: 20-25 r.p.m. Extrusion: Water content 29-31 kg / hr The results are shown in FIG.

As shown in FIG. 3, the extruder of the present invention has an extremely small amount of wear of the barrel, and is 8 to 1 compared with the conventional barrel made of stainless steel.
It is clear that the wear resistance is remarkably improved with 0 times.

Experimental Example 2 Abrasion of an extruder according to the present invention equipped with an alumina ceramic screw and an inner barrel made of ultra-high molecular weight polyethylene (Newlite) and a conventional extruder provided with a SUS304 stainless steel screw and a SUS304 stainless steel barrel I investigated the adverse effects on the product.

That is, the kneaded material used in Experimental Example 1 was extruded by each extruder in the same manner as in Experimental Example 1, and the extruded tube obtained was
A porous body was obtained by firing at 500 ° C. The color tone and whiteness of this porous body were measured with a color difference meter for comparative examination.

The results are shown in Table 1.

As is clear from Table 1, the conventional stainless barrel and stainless screw extruders are
It has a pale pink color (this was found to be due to the higher contents of Cr and Ni of the stainless steel component from the results of the emission light analysis), and the one according to the present invention gives a white smoky feeling. Gave.

As a result, it is clear that the extruder of the present invention does not adversely affect the product due to the wear of the barrel and the screw.

[Effects of the Invention] As described in detail above, the extruder of the present invention includes a barrel including a ceramic screw, a metal barrel main body, and a resin inner barrel having a self-lubricating property fitted therein. In addition to having excellent abrasion resistance of the screw, it can improve the lubricity of the inner wall surface of the barrel that comes into contact with the extrusion molding material, and the contact resistance is extremely small, resulting in significant barrel wear. Will be reduced.

Therefore, the life of the barrel is extended and the replacement frequency is reduced, so that efficient extrusion molding can be performed under stable extrusion molding conditions.

The resin that makes up the inner barrel is lighter than metal, and the entire barrel can be made thinner due to improved wear resistance, so the weight and size of the extruder can be reduced. You can Therefore, workability and handleability at the time of disassembling, assembling, maintenance and the like of the extruder are also improved.

Since the inner barrel is chemically stable and made of non-toxic resin in addition to less abrasion, even if an abrasion substance is mixed into the product, it does not adversely affect the product.

It is possible to produce a high-quality extrusion-molded product at low cost with good working efficiency.

Moreover, since the inner wall surface of the inner barrel is provided with the concave groove and / or the ridge extending in the longitudinal direction of the barrel, the extrusion molding material can be efficiently extruded, which saves power. This is possible and the running cost can be significantly reduced, which is extremely advantageous.

[Brief description of drawings]

1 and 2 are views of a barrel portion of an extruder according to an embodiment of the present invention, in which FIG. 1 is a sectional view and FIG.
It is sectional drawing which follows the II-II line of a figure. FIG. 3 is a graph showing the results of the abrasion resistance test obtained in Experimental Example 1. 1 ... Barrel body, 2 ... Inner barrel, 3 ... Screw.

Claims (3)

[Claims] 1. An extrusion molding machine in which a ceramic screw is inserted in a barrel, wherein the barrel comprises a metal barrel main body and a self-lubricating resin inner barrel fitted in the metal barrel main body. An extrusion molding machine provided with the resin inner barrel, wherein an inner wall surface of the resin inner barrel is provided with a groove and / or a ridge extending in the longitudinal direction of the resin inner barrel. Extruder. 2. A resin having self-lubricating property is ultra-high molecular weight polyethylene.
An extruder according to item. 3. The ceramic screw has a shaft portion and a screw blade projecting from a peripheral surface of the shaft portion, and at least the screw blade is made of ceramics. The extruder according to item 2.