JPH02208015A - Heating cylinder - Google Patents

Abstract

PURPOSE:To reduce material cost, and to facilitate machining by diffused-joining both sections, a polymer powder transport section of which is formed of a low-strength steel and another section of which is shaped of a high-strength steel, through hot isotropic pressure treatment. CONSTITUTION:A polymer powder transport section 2 to which a polymer powder supply hole 5 is formed is shaped of a low-strength steel such as carbon steel for mechanical structure, and another section (a melting section) 3 is formed of a high-strength steel such as Cr-Mo steel, Ni-Cr-Mo steel, high Mn steel, 12 Cr group stainless steel, an Ni base alloy, etc., and the two members 2, 3 are diffused-joined through HIP treatment and shaped integrally. The polymer powder transport section to which the high pressure of a cylinder body does not work is formed of the low-cost low-strength steel, and another section to which high pressure works is shaped of the high-strength steel, thus reducing material cost. The powder transport section is formed of the low-strength steel, thus easily allowing machining, then curtailing the cost of machining.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heating cylinder for an injection molding machine or an extrusion machine for various plastics, rubbers, ceramics, etc.

(Prior Art) Conventionally, an injection molding machine used for injection molding of plastics, etc. has a nozzle part 52 and an outer periphery for injecting molten polymer into a mold, as shown in FIG. The heating cylinder 53 includes a heating cylinder 53 equipped with a heater 60 for melting polymer powder, a screw 55 inserted into the cylinder 53, and a screw drive unit that rotates and drives the screw 55 forward and backward. The drive unit includes a hydraulic motor 18 and an injection hydraulic cylinder 1.
It consists of 9. In addition, the heating cylinder 53
On the side of the screw drive section, a polymer powder supply hopper 57 and a polymer powder supply hole 56 for supplying the cylinder heliumer powder from the hopper are provided.

The polymer powder, which is the raw material for the molded body, is supplied from the powder supply hopper 57 to the heating cylinder 53 through the supply hole 56, while being heated and melted by the heater 60 in the cylinder 53, and is transferred to the nozzle section by the rotation of the screw 55. Sent to the side. Then, as the screw 55 moves forward, it is injected (injected) into a molding die to form a molded body.

Therefore, as described above, the heating cylinder 53 is divided into a polymer powder transport section B including the powder supply hopper 57 on the screw drive section side, and a polymer powder melting section C on the nozzle section 52 side. be able to.

On the other hand, the inner surface of the heating cylinder 53 may be abraded by the plastic material or the mixture in the plastic material transferred through the cylinder 53 by the screw 55, or by thermal decomposition of additives contained in the plastic material, etc. Easily corroded by substances that cause For this reason, the cylinder body is made of nitrided steel and the inner surface is nitrided, and the inner layer of the cylinder made of high-strength steel is coated with an inner layer made of a high-alloy material with excellent wear and corrosion resistance using a centrifugal force casting method. It is formed by melting or by sintering by hot isostatic pressing treatment (hereinafter referred to as rHIP treatment).

(Problem to be Solved by the Invention) During injection molding using the above-mentioned injection molding machine, the polymer melting part C1 of the heating cylinder, especially near the nozzle part, is exposed to high temperatures of 200 to 400°C, and the temperature inside the cylinder is Since the pressure is also high, exceeding 2500 kg/cil, the cylinder body is usually made of high-strength steel.

However, the above-mentioned high pressure acts only on the part near the nozzle part of the cylinder, and the parts of the polymer powder transport part B and the melting part C near the transport part mentioned above are not subjected to high pressure. . Therefore, conventional heating cylinders are made entirely of expensive high-strength steel, including parts where high pressure is applied and parts where only low pressure is applied.
The disadvantage was that the material cost was high. In addition, the shape of the powder transport section B is complicated due to the formation of the powder supply hole 16 and attachment to the drive section frame, and since high-strength steel material has poor machinability, it takes a long time to process. It also had the disadvantage of high processing costs.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a heating cylinder that reduces material costs and is easy to machine.

(Means for Solving the Problems) The present invention, which has been made to achieve the above-mentioned object, is a cylinder for inserting a screw of an injection molding machine or an extruder, and the inner surface of the cylinder body l has a wear-resistant material. In the heating cylinder, the inner layer 4 is formed of a high-alloy material with excellent strength and corrosion resistance. The structure of the invention is that it is made of high-strength steel, and that both parts are diffusion bonded by hot isostatic pressing.

(Function) In the present invention, at least the polymer powder transport portion of the cylinder body on which high pressure does not act is formed of inexpensive low-strength steel, and the other portions on which high pressure acts are formed of high-strength steel. Material costs can be reduced. Furthermore, since the powder transport section is made of low-strength steel as described above, it can be easily machined, and processing costs can be reduced.

Furthermore, since the two members are diffusion bonded by HIP processing, there are very few defects in the structure at the bonded portion, and the bonding portion has strength equal to or greater than that of conventional integrally formed products.

Furthermore, during the HIP process, the inner layer made of the high-alloy material mentioned above is also sintered and formed at the same time. Therefore, manufacturing costs can be further reduced.

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

FIG. 1 shows a heating cylinder according to an embodiment.

The main body 1 of the cylinder has at least a polymer powder transporting part 2 in which a polymer powder supply hole 5 is formed, which is made of a low-strength steel material such as carbon steel for mechanical structures, and other parts (melting part).
3 is, for example, Cr-Mow4, N i -Cr -
The two members 2 are made of high-strength steel such as Mo steel, high Mn steel, 12cr stainless steel, and Ni-based alloy.
．． 3 is integrally formed by diffusion bonding by HIP processing.

In the illustrated example, the joining position A of the two members 2.3 is located adjacent to the powder transporting part and the melting part in the heating cylinder described above, but the polymer powder is partially melted in the melting part 3. (preferably in a range of about 1/3 of the length of the melting section). This is because the pressure acting on the heating cylinder is relatively low in the partial melting range.

Further, as described above, the two members 2.3 are diffusion bonded by HIP processing. When joining by other joining methods, such as welding, it is necessary to form a deep groove at the joint between the two in order to obtain sufficient strength, and welding defects are likely to occur at the joint, resulting in mechanical damage to the joint. inferior in nature. On the other hand, HIP treatment is extremely unlikely to cause defects in the joint, and mechanical properties equivalent to or better than those of an integrally molded product can be obtained.

An inner layer 4 made of a high alloy material with excellent wear resistance and corrosion resistance, such as a Ni-based alloy material or a Co-based alloy material, is formed on the inner surface of the cylinder body 1 described above. The inner layer 4 can be formed on the inner surface of the cylinder body 1 by melting the high-alloy material after forming the cylinder body 1, and then melting the inner layer 4 by centrifugal casting.

Alternatively, the high-alloy material powder may be formed into a high-density sintered body by HIP processing and then diffusion bonded to the inner surface of the cylinder body 1. In particular, if it is formed during the HIP processing amount of the cylinder body 1 mentioned above, -
This is preferable because the cylinder main body 1 and the inner layer 4 can be formed at the same time in one HIP process, and processing costs can be reduced.

An outline of the method for manufacturing the heating cylinder of this example will be described below.

First, as shown in FIG. 2, a lower cylindrical member 7 made of the aforementioned low-strength steel material and an upper cylindrical member 6 made of high-strength steel material are prepared, and the axial end faces of both are concentric. While in contact with the cylindrical material 8, the material is joined at the welding portion 9 to temporarily secure the two. The above-mentioned welding is a temporary fixing process until the above-mentioned two members are diffusion-bonded by IIP processing, and the depth of the groove of the welded part 9 is completely removed by machining after joining the cylinder body 1. depth.

This is to avoid leaving a welded part with poor mechanical properties in the joint.

Next, as shown in FIG. 3, the lower lid 11 is fixed to the lower end of the lower cylindrical member 7, and the lower end is mounted.

Then, a cylindrical or cylindrical insert member lO made of ordinary steel or the like is concentrically inserted into a hole formed along the axis of the cylindrical material 8. Incidentally, the insertion member 10 is fitted into the lower part 1 [11 and supported concentrically.

The gap between the outer circumferential surface of the inner member 10 and the inner circumferential surface of the cylindrical material 8 is equal to the thickness of an inner layer to be formed in the gap portion by HIP processing in a later step and an alloy powder layer for forming the inner layer. This is the contraction amount.

Next, the gap between the cylindrical material 8 and the inner member is filled with the high alloy powder 12 having excellent wear resistance and corrosion resistance, and then a degassing pipe 13 is inserted into the end of the upper cylindrical material 6. The upper lid 14 provided with the above is fixed by welding.

After vacuum degassing is performed through the degassing pipe 13, the degassing pipe 1
3. Seal and HIP. By the HIP process, the cylindrical material 8 is joined and fixed together, and an inner layer is formed on the inner surface of the material 8.

After the HIP process, the insert member 10 is cut and removed, and the inner peripheral surface is honed to a predetermined inner diameter of the cylinder. In addition, the outer peripheral surface of the cylindrical material 8 is also machined to a predetermined dimension, and polymer powder supply holes etc. are formed in the lower cylinder 7.
A cylinder body is obtained by forming into parts. Although the shape of the vicinity of the powder supply hole is complicated, this part is made of low-strength steel material as described above, so it is easy to machine.

Of course, the inner layer may be formed by centrifugal casting, HIP processing, etc. after the cylindrical material 8 is joined by HIP.

Further, although this embodiment describes a heating cylinder of an injection molding machine, the present invention is not limited to this, and can also be applied to a cylinder of an extruder.

A specific manufacturing example of the cylinder body will be described below.

(1) Inner diameter 57mmφ, outer diameter 145ttmφ, length 700mmjl! Cr-Mo rope material (SCM440)
An upper cylindrical member made of the same size and a lower cylindrical member made of a carbon steel material for mechanical structure (S25C) having the same dimensions were manufactured.

(2) With one end of the two members in the axial direction concentrically touching each other as shown in FIG. 2, they were temporarily joined by TIG welding to obtain a cylindrical material.

(3) After fixing the lower cover to the lower end of the lower cylindrical material by welding, insert a cylindrical inner member with an outer diameter of 40 Mφ into the hole in the axial center of the cylindrical material, and fit it into the lower cover. They were supported concentrically. The lower cover and the insert were made of carbon steel (S25C) for mechanical structures.

(4) The gap between the cylindrical material and the inserted member was filled with Ni-based alloy powder, and the top cover provided with the degassing pipe was fixed by welding.

The chemical composition of the Ni-based alloy is Cr: 16% in weight%.
, C: 0.7%, Si: 4.2% Fe: 4
%, B: 3.3%, the remainder was substantially Ni.

(5) After vacuum degassing the alloy powder layer using the degassing tube, seal the degassing tube and apply 1000℃, 1000kg/d
HIP treatment was performed for an hour.

(6) The insert member was cut and removed, and the inner diameter was set to 45 mmφ by honing.

(7) The outer periphery was also machined, and polymer powder supply holes were formed in the lower cylindrical part, with an inner diameter of 45 mm, an outer diameter of 140 mm, and a length of 1255 mm. , got a cylinder of.

In the cylinder body obtained above, no defects were observed in the structure of the joint between the upper cylindrical material made of Cr-Mo steel and the lower cylindrical material made of mechanical structural carbon steel, and HI
It was confirmed that the bonding was completely fixed by the P treatment.

When the cylinder was assembled into an injection molding machine and used, no abnormality was observed in the heating cylinder under the operating conditions of 250°C and 2000 kg/cii (7) until it was replaced due to wear of the inner layer.

(Effects of the Invention) In the present invention, at least the polymer powder transporting part of the heating cylinder body to which high pressure does not act is formed of low-strength steel, and the other parts to which medium to high pressure acts are formed of high-strength steel. Therefore, material costs can be reduced. Furthermore, since the polymer powder transport section formed of the low-strength steel material can be easily machined, processing costs can also be reduced.

Further, since the low-strength steel material and the high-strength steel material are diffusion-bonded by HIP processing, it is possible to obtain a heating cylinder main body having a joint portion with few defects and excellent mechanical properties.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a heating cylinder according to the present invention, and FIG.
3 and 3 are explanatory diagrams showing a method of manufacturing a cylinder body, and FIG. 4 is a partially sectional explanatory diagram showing an example of a conventional injection molding machine. DESCRIPTION OF SYMBOLS 1... Cylinder body, 2... Polymer powder transport part, 3... Other parts (melting part), 4... Inner layer.

Claims (1)

[Claims] (1) A cylinder for inserting the screw of an injection molding machine or an extrusion machine, with an inner layer (4) made of a high alloy material with excellent wear resistance and corrosion resistance on the inner surface of the cylinder body (1). In the formed heating cylinder, in the cylinder body (1), at least the polymer powder transport part (2) is made of low-strength steel material, and the other part (3) is made of a low-strength steel material.
A heating cylinder, characterized in that the cylinder is made of high-strength steel, and both parts are diffusion bonded by hot isostatic pressing.