JPH036201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cylindrical molded product such as a cylinder lighter material for an internal combustion engine.

As a conventional method for manufacturing a cylindrical molded product, there is a method using a mold shown in FIGS. 1 and 2, for example. That is, FIG. 1 shows a rear extrusion mold 1 for producing a cylindrical molded product from a solid cylindrical material. In the figure, numerals 2 and 3 are pressure receiving plates attached to a slide (not shown) of a press machine via an attachment plate 4, and 5 is a punch attached to the pressure receiving plate 3. 6 and 7 are pressure receiving plates provided on a polster (not shown) of the press machine, and 8 is a die attached to the pressure receiving plate 7. A reinforcing ring 9 is fitted around the outer periphery of the die 8 by shrink fitting or the like. 10 is an ejector provided through the pressure receiving plate 67;
A counter punch 12 is attached to the head 11 of 0. Extrusion mold 1 with such a configuration
After inserting a cylindrical material into the die 8, the punch 5 is press-fitted into the die 8, and the material is pushed out behind the punch 5, that is, in the opposite direction to the press-fitting direction of the punch 5, as shown in the figure. A cylindrical molded product 13 with a bottom is obtained. Next, after raising the punch 5, the ejector 10 is pushed and the formed cylindrical molded product 13 is pushed out from the die 8 and taken out.

On the other hand, FIG. 2 shows a forward extrusion type extrusion mold 14, which extrudes a hollow cylindrical material to produce a cylindrical molded product. In the figure,
15 and 16 are slides of the press device (not shown)
18 is a punch attached to the pressure receiving plate 16, and 19 is a mandrel. 20 and 21 are pressure receiving plates provided on the bolster (not shown) of the press device, and 22 is a die attached to the pressure receiving plate 21. 23 is a reinforcing ring fitted to the outer periphery of the die 22 by shrink fitting or the like;
Reference numeral 4 denotes an ejector provided to penetrate the pressure receiving plates 20 and 21. After inserting a cylindrical material into the die 22 of the extrusion mold 14 having such a configuration and fitting the mandrel 19 into the central hole of the material, the punch 18 is press-fitted into the die 22, and the punch 18 is removed from the die 22. , that is, the press-fitting direction of the punch 18,
The material is extruded while being squeezed to obtain a flanged cylindrical molded product 25 as shown in the figure. Next, the punch 18 and the mandrel 19 are raised to extract the mandrel 19 from the center shaft hole of the cylindrical molded product 25, and then the ejector 24 is pushed up to push out the cylindrical molded product 25 from the die 22 and take it out.

However, among such conventional manufacturing methods for cylindrical molded products, in the backward extrusion method shown in Fig. 1, the extruded molded product has a cylindrical shape with a bottom, so it does not fit into containers, etc. This is convenient when used as raw material for cylinder liners in internal combustion engines, but the bottom part must be removed by punching or cutting, which requires one extra process and reduces the material cost. There are problems such as poor yield. In addition, in the method shown in Fig. 2, the extruded molded product has a cylindrical shape with flanges, so it is fine in the case of flanged cylinder liner rough material, but in the case of straight cylinder liner rough material, the flange Since cutting is required for this part, one extra step is required.
In the case of thin-walled products such as raw material for cylinder liners, deformation of the raw material for cylinder liners may occur due to the pressure applied when extruding them with the ejector. There were problems such as the need to remove excess thickness by cutting.

On the other hand, cast iron is currently the most widely used cylinder liner rough material for internal combustion engines, but in recent years, powder cylinder liner rough material has been studied in order to provide wear resistance and low friction properties. ing. However, when trying to manufacture thin-walled long products such as cylinder liner blanks using powder materials, lamination occurs when molding is performed using the commonly used die-setting method, which is highly productive, so cold isostatic pressing or other methods are required. It was necessary to use a molding method with relatively low productivity, and it was difficult to sinter a thin-walled, long object without distorting it.

This invention was made by focusing on such conventional problems, and includes an inner circumferential surface of a die having an inner hole,
A gap is formed between the die and the outer circumferential surface of a core rod disposed concentrically and movably relative to the die, and a punch that can be inserted into and separated from the gap is provided, and the inner circumferential surface of the die or Inserting the core rod into the die into the die, the core rod having a forming mold formed by providing a tapered surface toward the gap on the outer peripheral surface of the core rod or on both the inner and outer peripheral surfaces thereof to form a constricted part. a step of inserting a heated cylindrical powder molding material; a step of inserting the punch into the void and press-fitting the cylindrical powder molding material halfway into the constricted portion with the punch; and inserting the punch from the void. A step of inserting a new heated cylindrical powder forming material into the gap while being separated from the die and the core rod, and inserting the punch into the gap and using the punch to form the new cylindrical powder. a step of press-fitting the molding material halfway into the constricted part and completely extruding the cylindrical powder-forming material previously press-fit halfway through the new cylindrical powder-forming material from the constricted part; This method attempts to solve the above-mentioned problems by providing a method for producing a cylindrical molded product, which includes a step of extracting the product from a die.

The present invention will be explained below based on the drawings. FIG. 3 shows an example of an extrusion mold for carrying out the method according to the invention. To explain the structure, 31 is a base block provided on a base (not shown) of a press machine, and 32 is a base plate fixed to the base block 31. A die 33 is fixed to the center of the base plate 32, and a part of the inner circumferential surface 34 of the die 33 has a tapered surface 35 that protrudes toward its axis as it goes downward (downward in the figure). The tapered surface 3
A first tapered portion 38 is provided, which is comprised of a flat surface 36 continuing from the flat surface 36 and an opposite tapered surface 37 continuing from the flat surface 36. The taper angle α of the tapered surface 35 is 5
The angle is preferably 70 degrees or more, and most preferably 10 to 30 degrees. Reference numeral 39 denotes a molded support that is attached across the base plate 32 and the lower end surface of the die 33. This molded product receiver 39 is provided with holes 40a and 40b that pass vertically through its center and are coaxial with the center axis of the die 33, and furthermore, holes 40a and 40b are provided in the center of the molded product receiver 39, and the holes 40b are concentric with the central axis of the die 33. A hole 41 for taking out items is provided. 42 is a lower ram of the press machine, and this lower ram 42 has a core rod pressure receiving plate 43 and a core rod pressure receiving plate holder 44.
It is fixed by. 45 is erected on the core rod pressure receiving plate 43 by a core rod cover 46, concentrically with the central axis of the die 33, and is connected to the lower ram 42.
holes 40a, 4 of the molded product receiver 39 as the
It is a core rod that penetrates through 0b and can be inserted into and extracted from the die 33 concentrically. This core rod 45
The main part 47 has a cylindrical shape with an outer diameter smaller than the inner diameter of the die 33, and when inserted into the die 33, its outer peripheral surface 48 and the inner peripheral surface 34 of the die 33
A gap 49 is formed between the two. Further, a part of the outer circumferential surface 48 of the core rod 45 has a tapered surface 50 that protrudes toward the gap as it goes downward, and a flat surface 51 that continues to the tapered surface 50.
and a tapered surface 52 opposite to the flat surface 51. When the core rod 45 is at its upper limit as shown in FIG. is the inner peripheral surface 3 of the die 33
4 and cooperates with each other to form a constricted portion 54 in the gap 49. The taper angle β of the second tapered portion 53 is preferably 5 degrees or more and 70 degrees or less, and most preferably in the range of 10 to 30 degrees. Reference numeral 55 designates a guide rod erected at the upper end of the core rod pressure receiving plate 43, and a guide rod 55 provided at a position opposite to the base plate 32.
6 and provides guidance for concentrically inserting the core rod 45 into the die 33. On the other hand, 57 is a punch pressure receiving plate fixed to the upper ram 58 of the press machine, and a punch 59 is attached to this punch pressure receiving plate 57 by a punch cover 60. As the upper ram 58 moves up and down, the punch 59 can fit into and come out of the gap 49 formed by the die 33 and the core rod 45, and is located at the bottom dead center. When the punch 59 is opened, the tip of the punch 59 is located within the gap 49 and approaches the constricted portion 54. Reference numeral 61 designates a guide rod erected at the bottom end of the punch pressure receiving plate 57, and
The punch 59 is slidably fitted into a guide bush 62 provided at a position opposite to the punch 59 to guide the punch 59 to fit into the gap 49 accurately.

FIG. 4 shows a thick and short cylindrical powder molding material (hereinafter simply referred to as the material) used to carry out the method according to the present invention. This material is a molded body made into a cylindrical shape by processing and molding a composition such as metal powder or wax, or a sintered body by sintering the molded body. These materials are much thicker and shorter than the cylinder liner rough material that is the final product, so they can be easily molded and sintered with extremely little deformation.

Also, this material is aluminum (AI)
It is preferable to use those of the same type. The reason is as follows. That is, in the method according to the present invention, as will be described in detail later, processing of a material is temporarily stopped in a semi-processed state, and after a new material is placed on top of the material, processing is resumed. There is a time loss between temporary suspension and restart. Due to this time loss, for materials that need to be heated to 700℃ to 1200℃ during processing, such as Fe-based molded bodies and sintered bodies, the temperature decreases significantly, and the deformation resistance becomes too high, making it difficult to extrude. However, even if extrusion is possible, the extrusion pressure becomes extremely high, and if the materials of the die and core rod are not carefully selected, their lifespan will be extremely shortened. However, in the case of Al-based molded bodies and sintered bodies, the heating temperature during processing is 300°C to 550°C.
℃ is sufficient, it is possible to process the die or core rod without a significant temperature drop by heating it with a well-known appropriate means, and even if there is a slight temperature drop, Fe-based molded products can be Since the deformation resistance is lower than that of sintered bodies and sintered bodies, the life of dies and core rods cannot be significantly shortened. FIG. 9 shows an example of a mold equipped with a heating means, in which a die 33 and a base plate 3
2, and a heater 72 is built into the space 71. Also, Bushiyu Stay 56
a, 62a are erected on the base plate 32, and the bushes 56b, 62b are driven into the inner surface of the stay.
Avoid being affected by heat.

Next, an example of the method of the present invention using the press machine and mold will be described.

First, the lower ram 42 is raised to the top dead center, and the core rod 45 is raised to its upper limit by the guidance of the guide bar 55 and the guide bush 56, and the die 3 is moved so that its upper end almost coincides with the upper surface of the die 33.
Insert into 3. After the lower ram 42 is stopped, the material 30 heated to 300 DEG C. to 550 DEG C. is inserted into the gap 49 between the die 33 and the core rod 45, as shown in FIG. If the heating temperature of the material 30 is below 300°C, the deformation resistance will become too high and the extrusion pressure will increase, which may shorten the life of the die 33 and the core rod 45, or in extreme cases, it may become impossible to extrude, which is undesirable. Moreover, if the heating temperature is higher than 550° C., crystal grains become coarse, a liquid phase occurs partially, and so-called sweat beads occur on the surface of the material 30, which is not preferable. The material 30 inserted into the gap 49 comes into contact with the upper end of the constricted portion 54 and stops. Next, when the upper ram 58, which had been stopped at the top dead center, is lowered, the punch 59 along with the upper ram 58 is guided by the guide rod 61 and the guide bush 62, and moves the die 33 and the core rod 45.
The material 30 is pressed into the constricted portion 54 by fitting into the gap 49 . The state when the upper ram 58 and punch 59 reach the bottom dead center and stop is the fifth state.
It is shown in the figure. At this point, the material 30 is press-fitted into the constriction part 54 with a little of its upper end remaining, and the lower end that has passed through the constriction part 54 is inserted into the constriction part 54.
4 into a cylindrical shape with predetermined dimensions.
Next, after raising the punch 59 together with the upper ram 58 to the top dead center and stopping, the punch 59 is heated to 300°C in the cavity 49.
Insert a new material 30a heated to ~550°C.
The new material 30a is inserted into the drawing section 5 as shown in FIG.
4 is placed on top of the material 30 that has been press-fitted into the material 30. Next, the upper ram 58 is lowered again and a new material 30a is press-fitted into the constricted portion 54 until the punch 59 reaches the bottom dead center in the same manner as described above. As a result, as shown in FIG. 7, the material 30 that was previously press-fitted halfway into the constricted portion 54 is pressed by the punch 59 via the new material 30a, and is completely inserted into the constricted portion 54.
The molded product 30b is formed into a cylindrical molded product 30b having a predetermined size and placed on the bottom surface 39a of the molded product receiver 39. Next, the upper ram 58 is raised to the top dead center and stopped, and then the lower ram 42 is lowered to the bottom dead center to raise the upper end surface 45a of the core rod 45 to approximately the same level as the bottom surface 39a of the molded product receiver 39 or Lower it to a lower position. Then, the cylindrical molded product 30b is taken out from the take-out hole 41 of the molded product receiver 39. At this time, the material 30a press-fitted into the constricted part 54 is held in the constricted part 54 as it is. Next, the lower ram 42 is raised again to the top dead center and stopped, and the core rod 45 is inserted into the die 33 and positioned at the upper limit.
Next, a new material is inserted into the gap 49 and molded in the same manner as described above. In addition, during the forming process, the temperature drop of the previous material is avoided as much as possible between the time when one material is press-fitted into the constricted part 54 and the time when the next material is press-fitted and the original material is pushed out from the constricted part 54. Therefore, it is desirable to heat the die 33 or the core rod 45 by an appropriate means such as using a plug-in burner or installing a heater adjacent to the die 33 or the core rod 45.

FIGS. 8a and 8b show the strain distribution inside the material 30 during molding by the method according to the present invention. Figure 8(a) shows the strain distribution when the taper angle α of the tapered portion 38 of the die 33 and the taper angle β of the taper portion 53 of the core rod 45 are larger than 70 degrees (in the illustrated example, both α and β are 90 degrees). FIG. 8(b) shows the strain distribution state when α and β are 70 degrees or less and 5 degrees or more (in the illustrated example, both α and β are 15 degrees). As is clear from Fig. 8a, when α and β are 70 degrees or more, the flow in the center becomes large due to the change in the direction of the structure of the material 30, and the die is formed before the structure is sufficiently consolidated. Pushed out from 33. In other words, a large tensile stress is applied to the tissue in the center. If the material 30 is a wrought aluminum material with a large elongation, this tensile stress can be sufficiently followed, but if the material is a sintered aluminum powder with a relatively small elongation or an aluminum powder molded material with almost no elongation. In the case of the body, the tissue cannot fully follow this tensile stress and is sheared, resulting in the so-called center bursting phenomenon (severon crack). On the other hand, α,
When β is less than 70 degrees and more than 5 degrees, as is clear from FIG. 8b, the structure of the material 30 is
5, 50, the flat surface 3
It reaches maximum density at positions 6 and 51 and is pushed out of the die 33. That is, until it reaches the position of the flat surfaces 36, 51, most of the compressive stress is applied to the structure of the material 30, and only a small amount of tensile stress is applied. After being extruded from the die 33, a certain amount of tensile stress is applied, but since the tensile stress is applied after the structure of the material 30 is sufficiently consolidated and retains a large elongation, center bar staying occurs in the center. will never occur. Furthermore, when α and β are 5 degrees or less, the tapered surfaces 35 and 50 must be lengthened to obtain the necessary cross-sectional reduction rate, which makes the die 33 and core rod 45 longer than necessary, resulting in a reduction in the contact area. Due to the increase in frictional force, the resistance to extrusion and deformation increases. It is preferable that α and β be at the same angle, but if it is necessary to create a difference in the density distribution of the tissue between the inner and outer peripheral surfaces of a cylindrical molded product, α and β should be set at the same angle. You can do it at a different angle.

Examples are shown below.

Example 1 Al/25Si atomized alloy powder, electrolytic Cu powder, flame spray Mg powder, atomized Al powder, and wax were added to 22% Si, 3% Cu, 1% Mg, and 1.5% wax.
The powder was weighed so as to have a significant percentage of remaining Al, and mixed for 20 minutes using a V-blender. The Al-25Si atomized alloy powder was annealed in _N2 gas at 400°C for 1 hour. After mixing, the mixed powder is pressurized with a pressure of 5 tons/cm ² to form a powder with an outer diameter of 90 mm and an inner diameter.
A powder compact with a length of 64 mm, a height of 29 mm, and a density ratio of 93% was produced. After applying Datsuku Dispersion No. 2412 (graphite powder dissolved in petroleum solvent) manufactured by Nippon Acheson Co., Ltd. to this green compact, it was dried and heated at 450℃ for 30 minutes in purified _N2 gas. and charged into a mold,
A cylinder liner rough material having an outer diameter of 80 mm, an inner diameter of 74 mm, and a height of approximately 125 mm was manufactured by the method described above. A cross-sectional reduction rate of 77% and a density ratio of nearly 100% were obtained. The mold is heated with a burner so that the temperature does not drop, and the surface temperature of the part in contact with the charged material is 300℃.
Ensured that the temperature did not drop below ℃.

The taper angle of the die was 18°, the taper angle of the core rod was 18°, and the maximum extrusion pressure was 9 tons/cm ² . The cylinder liner rough material manufactured in this way does not deform or crack, and has high tensile strength.
T6 treated material showed 45Kg/ ^mm2 .

Example 2 Al-20Sig atomized alloy powder, electrolytic Cu powder, pulverized Mg powder, Cu coated graphite powder (Cu coating amount 30% by weight), atomized Al
The powder was weighed so as to have 17% Si, 4% Cu, 0.5% Mg, 3% graphite, 1.5% wax, and residual Al parts by weight, and was mixed in a V-blender for 20 minutes. In addition, the Al-20Si atomized alloy powder was heated to 400% in _N2 gas.
It was used after being annealed at ℃ for 1 hour. The mixed powder that has been mixed is charged into a mold and pressurized with a pressure of 3.5 tons/ ^cm2 .
A powder compact with a height of 45 mm and a theoretical density ratio of 93% was manufactured.

Next, this powder compact was heated at 400°C for 1 hour in purified N ₂
After heating in gas and volatilizing the wax content,
A powder sintered body was produced by sintering at 550°C for 1 hour in _N2 gas with a dew point of -40°C.

Next, after coating the surface of this powder sintered body with Datsuku Dispersion No. 2412 manufactured by Nippon Acheson Co., Ltd.,
The dried and heated material was charged into a die equipped with a heater as shown in FIG. 9, and a cylinder liner rough material having an outer diameter of 80 mm, an inner diameter of 74 mm, and a height of about 125 mm was produced by the method described above. The cross-sectional reduction rate was 66.7%. The temperature of the mold was maintained at 400°C, and the taper angles of the die and core rod were set to the following three types.

Die taper angle 15°, core rod taper angle
15° Die taper angle 15°, core rod taper angle
0゜ Die taper angle 0゜, core rod taper angle
15° That is, in this embodiment, either the inner circumferential surface of the die or the outer circumferential surface of the core rod is apertured by providing one (corresponding to the above) or both (corresponding to the above) with a tapered surface toward the gap between both surfaces. It forms a part.

The maximum extrusion pressure was approximately 7 tons/cm ² in the case of , and approximately 6.5 tons/cm ² in the case of , and no deformation or cracking occurred in either case.

The density distribution is the density ratio over the entire surface in the case of
In the case of 100%, the density ratio near the outer peripheral surface was 100%, but the density ratio near the inner peripheral surface was 98%, and some pores were observed. In contrast to the case of , the density ratio near the inner peripheral surface was 100%, but the density ratio near the outer peripheral surface was 98%, and some pores were observed. However, even in this case, the pores could be removed through final machining, so it could be used satisfactorily as a raw material for cylinder liners.

As explained above, according to the present invention, there is provided a method for manufacturing a cylindrical molded product, and a method for manufacturing a cylindrical molded product, in which the inner circumferential surface of a die having an inner hole and a core rod arranged concentrically with the die and movable relative to the die A gap is formed between the die and the outer circumferential surface of the die, and a punch that can be inserted into and separated from the gap is provided, and a punch is provided on the inner circumferential surface of the die, the outer circumferential surface of the core rod, or both of these inner circumferential surfaces and outer circumferential surfaces. Inserting the core rod of the mold, which has a tapered surface toward the void to form a constricted portion, into the die and inserting a heated cylindrical powder material into the void, and inserting the punch into the void. and press-fitting the cylindrical powder molded material halfway into the constricted part with the punch, and pulling out the punch from the gap and separating it from the die and the core rod, and inserting a new heated cylindrical material into the gap. a step of inserting a powder molding material, and inserting the punch into the gap, and using the punch to press the new cylindrical powder molding material halfway into the constricted part, and inserting the new cylindrical powder molding material through the new cylindrical powder molding material. The process of completely extruding the cylindrical powder molded material, which has been press-fitted halfway through, from the constriction part, and the process of extracting the core rod from the die, makes it easier to manufacture conventional cylindrical molded products. As a result, a molded product having no bottom or flange like the molded product produced can be obtained. As a result, processes such as punching and cutting are not necessary, and the yield of material is improved, and even thin-walled and long cylindrical molded products can be manufactured without deformation. Furthermore, since a relatively thick and short powder compact or powder compact is used as the powder compact material, it is easy to manufacture.

Furthermore, the method for manufacturing a cylindrical molded product according to the present invention has the following effects. That is,
In all cylindrical molded products manufactured by conventional methods, the part that is extruded first is in a free extrusion state, so the density of the tissue at the tip is low, and the tip also has a rounded shape. If a material with low ductility is used, such as a powder compact or a powder sintered compact, cracks will occur at the tip and the cracks will have to be removed, further reducing the yield. In order to prevent this, it is necessary to apply back pressure to the extruded material, and a means for that purpose is required, but according to the method according to the present invention, the material is first inserted halfway into the die. Since the material is pushed out while pressing against the material, it is essentially the same as applying back pressure. As a result, the distal end of the newly inserted material has a higher tissue density and a flat shape, and no cracks occur.

Furthermore, even if a cylindrical material manufactured by a method other than powder material is extruded by the method according to the present invention,
The characteristics of the obtained cylindrical molded product are hardly improved due to the characteristics of the material, whereas when a powder molded product is extruded, the powders are physically bonded together and the overall strength and wear resistance are improved. Improves sex. Further, when a powder sintered body is extruded, the structure is compacted, so the strength is improved, and the retention of additive substances (for example, graphite) is improved, so the wear resistance is improved.

[Brief explanation of drawings]

Figure 1 is a front cross-sectional view of a backward extrusion type extrusion molding apparatus for carrying out the conventional method for manufacturing cylindrical molded products, and Figure 2 is a front sectional view of a front extrusion type extrusion molding apparatus for performing the conventional method for manufacturing cylindrical molded products. 3 is a front sectional view showing an example of an extrusion molding apparatus for carrying out the method for manufacturing a cylindrical molded product according to the present invention; FIG. 4 is a front sectional view of an extrusion molding apparatus according to the present invention. Perspective view of a cylindrical powder molding material used to carry out the method for manufacturing the product, No. 5
6 and 7 are a front cross-sectional view and FIG. 8a, respectively, showing a state in which each step of the method for manufacturing a cylindrical molded product according to the present invention is carried out by the extrusion molding apparatus shown in FIG. 3. , FIG. 8b are schematic explanatory diagrams showing the strain distribution inside the cylindrical powder molding material during molding by the method for manufacturing a cylindrical molded product according to the present invention, and FIG. 9 is a portion of the mold equipped with heating means. FIG. 30... Cylindrical powder molding material, 33... Die,
34... Inner circumferential surface of die, 38... First tapered part, 45... Core rod, 48... Outer circumferential surface of core rod, 49... Gap, 53... Second tapered part, 54... Squeezed part , 59...Ponchi.

Claims (1)

[Scope of Claims] 1. A gap is formed between the inner circumferential surface of a die having an inner hole and the outer circumferential surface of a core rod that is arranged concentrically with the die and capable of being inserted into and separated from the die. A punch that can be inserted into and separated from the cavity is provided, and either or both of the inner peripheral surface of the die and the outer peripheral surface of the core rod are provided with a tapered surface facing the cavity to form a constricted part. Inserting the core rod of the mold into the die and inserting the heated cylindrical powder molding material into the cavity, and inserting the heated cylindrical powder molding material into the cavity of the punch and using the punch to punch the cylindrical powder molding material. a step of press-fitting the punch halfway into the constricted portion; a step of extracting the punch from the cavity and separating it from the die and the core rod; and inserting a new heated cylindrical powder molding material into the cavity; and a step of inserting the punch into the cavity. Cylindrical powder molding is performed by inserting the new cylindrical powder molding material into the cavity and press-fitting the new cylindrical powder molding material halfway into the constricted part with the punch, and first press-fitting the new cylindrical powder molding material halfway through the hole. A method for manufacturing a cylindrical molded product, comprising the step of completely extruding the material from the squeezed portion. 2. The method for manufacturing a cylindrical molded product according to claim 1, wherein the cylindrical powder molded material is made of an aluminum-based material.