KR20050025140A - A process for producing a high density by high velocity compacting - Google Patents

Abstract

A method of producing a body from a particulate or solid material comprises filling a precompacting mould with the material, optionally vibrating the mould, pre-compacting the material and compressing it by at least one stroke with high kinetic energy in order to cause coalescence or high density of the material.

Description

Densification process by high speed molding {A PROCESS FOR PRODUCING A HIGH DENSITY BY HIGH VELOCITY COMPACTING}

The present invention relates to a method of making a body high density by coalescence or molding.

In WO-A1-9700751, a molding machine and a method for cutting rods using this machine are described. This publication also describes a method of deforming a metal body. The method uses the machine described in this publication, and preferably, a metallic material, preferably in solid form or in powder form, such as grain, pellets, etc., is preferably fixed to the end of a mold, holder, or the like. It is also characterized in that the material is thermally coalesced by a striking unit, such as an impact ram whose movement is influenced by the liquid. This machine is described fully in the above WO publication.

WO-A1-9700751 describes the formation of components such as spheres. The metal powder is fed to a tool divided into two parts, which are fed through a connecting tube. The metal powder is preferably gas automated. In order to affect the material contained in the spherical mold, the rod through the connection tube is susceptible to impact from the percussion machine. However, specifying a parameter as to how the body is made by this method is not shown in any embodiment.

Molding according to this publication is carried out in several steps, for example in three steps. These steps are executed very quickly and three strokes are made as described below.

Stroke 1: A very weak stroke, allowing most of the air to escape from the powder and orienting the powder particles to ensure no large irregularities.

Stroke 2: A stroke with a very high energy density and a high impact rate for local thermal coalescing of powder particles, whereby the particles are molded against each other resulting in a very high density. The local temperature rise of each particle depends on the degree of deformation during the stroke.

Stroke 3: A stroke with medium-high energy and high contact energy for the final formation of the substantial molding material body. After that, the molded body is sintered.

SE 9803956-3 describes a method and device for modifying a material body. This is actually an improvement of the invention described in WO-A1-9700751. The method according to SE 9803956-3 is characterized in that the striking unit is introduced into the material at a rate such that at least one rebounding motion of the striking unit occurs, at which time the rebounding is counteracting and accordingly the striking At least one additional stroke of the unit is generated.

The stroke according to the method described in WO-A1-9700751 causes a very high temperature rise locally in the material, which can lead to a phase change in the material during heating or cooling. When using a rebounding motion that generates at least one additional stroke in accordance with SE 9803956-3, this stroke moves back and forth and is caused by the kinetic energy of the first stroke and causes a continuous wave for longer periods. This causes further deformation of the material with a lower impulse than necessary when there is no reaction.

The machines according to these publications have now been found to not work so well. For example, the time interval between the strokes they mentioned is unachievable. Moreover, these publications do not include any embodiments that show that a body can be formed. Rebound strokes have also been found to cause cracking of the material.

Purpose of the Invention

It is an object of the present invention to achieve a low cost process for the efficient production of high density products from particulate or solid materials by coalescence or molding. Such products may include medical devices such as medical implants or bone cements in orthopedic surgery, tools such as surgical knives, or diagnostic equipment, or ball bearings, cutting tools, sinks, tubs, displays, glazing (especially Airplanes), non-medical devices such as lenses and optical covers. Another object is to obtain a product of this described type.

The purpose for achieving high density is based on the fact that high density is a requirement for high mechanical properties.

This process should not be limited to using the machine described above.

1A and 1B are schematic cross-sectional views of two embodiments of a machine for deformation of materials in the form of powders, pellets, grains, and the like;

2 to 5 are flow charts illustrating the process according to the invention,

6-36 are diagrams showing results obtained in a comparative test described in subsequent examples.

It has surprisingly been found that it is possible to mold different materials according to the new method as defined in claims 1 to 5 of the present invention. This material is, for example, in the form of powder, pellets, grains and the like, filled into the mold, pre compacted and molded by at least one stroke. The machine used in this method can be that described in WO-A1-9700751 and SE 9803956-3 with a vibration device added to obtain vibration of the tool or mold. The material may also be in solid form and inserted into the mold, using two or more strike units to release sufficient kinetic energy to form a body when striking the material and cause a higher density or coalescence of the material, It is susceptible to at least one stroke from two or more sides at the same time. The machine used in this case comprises at least two opposing strike units.

The method according to the invention can use hydraulics in the striking machine and can be constructed on the same principle as the machines used in WO-A1-9700751 and SE 9803956-3. When using pure hydraulic means in this machine, a striking unit may be provided to such machinery to release sufficient energy at a speed sufficient to achieve coalescence when impacting the material to be molded. This coalescence is adiabatic. The stroke is performed very quickly and for some materials, the wave in the material attenuates between 5 and 15 milliseconds. The use of hydraulics results in better sequence control and lower operating costs compared to the use of molded air.

However, the present invention is not limited to using a hydraulic machine. It is also possible to use a spring driven or electrically operated striking machine or machine using shaped air. It is not always necessary to obtain coalescence. In some cases, it is sufficient to carry out the molding to a higher density.

The optimum machine has a large-scale press for preforming and post compacting, and at least one small striking unit that can hit at variable speeds. Therefore, a machine according to this structure is probably more interesting to use. Different machines can also be used, one for preforming and subsequent molding and the other for molding.

The present invention relates to a method of making a body from particulate matter. This method includes the following steps.

a) filling the preform mold with a material in the form of powder, pellets, grains, etc.,

b) vibrating the mold,

c) preforming the material at least once by preforming means, and

d) shaping the material by at least one stroke in the forming mold, wherein the striking unit releases sufficient kinetic energy to form a body when striking the material inserted into the forming mold with the striking means, and coalescing or higher Causes the density of the material.

By using vibration, the particles in the preformed mold move closer to each other to push out air or gas between the particles and orient themselves so that they can be molded more easily. Thus, a higher density is already achieved before the preforming starts. The preforming thus starts not with loosely gathered powder but with more dense powder. Accordingly, less preforming strokes may be required. If vibration continues during the preforming step, higher densities will be achieved using the same preforming pressure.

The higher density achieved during the preform will facilitate the forming step.

Further advantages are obtained when the material is molded in two or more sides at the same time using two or more strike units.

The preform mold may be the same as the mold, which means that the material does not need to move between steps c) and d). It is also possible to use different molds and to move the material between steps c) and d) from the preform mold to the mold. This can only be done if a body is formed from the particulate material in the preforming step.

The present invention also includes the following steps.

a) inserting a solid material into the mold,

b) preforming the material at least once by preforming means, and

d) shaping the material in the mold by at least one stroke at two or more sides simultaneously using two or more strike units that release sufficient kinetic energy to form a body when striking the material,

The preforming means is preferably applied continuously to the material at the same or higher pressure by the strike unit during the forming step d).

By using a machine capable of striking the material in the mold from two opposing directions and shaping from the direction in which the particles in the powder can be more oriented, better contact between the particles is obtained and the particles are more effective Welding is the result. The body obtained is more uniform than the body made under the same energy and pressure applied in only one direction. Advantages arise from pre-molding and double-sided treatment during molding.

According to the present invention, a preferred method of making a body from particulate material can be described in the following manner.

1) The powder is pressed into the green body under vibration, the body is shaped by the impact into the (semi) solid body and thus energy retention in the body is achieved by subsequent molding. This treatment, which can be described as Dynamic Forging Impact Energy Retention (DFIER), involves three main steps.

a) Pressing

This pressurization step is almost the same as the low temperature and high temperature pressurization. This object is to obtain a green body from powder. It has proved to be most advantageous to carry out two moldings on the powder. Only one shaping resulted in a density of 2-3% lower than two successive shapings of the powder. This step is to prepare the powder by evacuating the air and aligning the powder particles in an advantageous manner. The density values of the green body are somewhat the same as for normal low temperature and high temperature pressurization.

b) impact

The impact stage is an actual high speed stage where the strike unit strikes the powder in a defined range. The mass wave starts in the powder and interparticle melting occurs between the powder particles. The speed of the striking unit seems to play an important role only during the first very short time. The amount of powder and the properties of the material determine the degree of interparticle melting that occurs.

c) energy retention

The energy retention step aims to produce the delivered energy in the solid body. This is a molding which has a pressure which is physically almost identical to the preforming of the powder. The result is an increase in density of the resulting body of about 1 to 2%. This is done, for example, by placing the striking unit on the solid body after pressure and impact which are about the same as in preforming, or by releasing the striking unit after the impact step. It is believed that more conversion of the powder will occur within the resulting body.

1a shows a machine for shaping and shaping material from the upper and lower sides. 1B shows a corresponding machine that can be molded and striked only from one side. For similar parts reference numerals are the same in both FIGS. 1A and 1B.

The machine shown in FIG. 1A comprises upper and lower striker devices 1a, 1b. Each striking device has an impact ram 2a, 2b that includes a weight 10 and is aligned within the impact ram housings 11a, 11b. The mass of the impact ram can be varied by adjusting the number of impact ram weights 10 inside the impact rams 2a and 2b. Between the striker devices 1a, 1b is a center comprising support rods 7 which connect the upper and lower static press tables 12a, 12b through which the upper and lower static preform press rams 5a, 5b pass. There is a part. In the figure two support rods 7 are shown. The machine includes two additional front and rear rods 7 (not shown in the figure). Upper and lower punches 9a and 9b are connected to the preformed rams 5a and 5b. The molding die table 13 is connected to the support rod while supporting the mold 8 aligned between the upper and lower punches 9a and 9b. The vibration device 6 is connected to the molding die table 13. There is also a hopper 3 in which the particles come out and are fed into the mold 8.

The machine of FIG. 1B includes the same parts as the machine of FIG. 1A with the following exceptions. The machine does not include the bottom impact device 1b and does not include the bottom static preform press ram 5b or the bottom static press table 12b. The lower punch 9b is connected to a rig fundament 4.

Process steps are shown diagrammatically in FIGS. 2 and 3 show a process without energy retention (using a non-DFIER machine) and FIGS. 4 and 5 show that there is energy retention (using a DFIER machine). 2 and 4 show a single-cycle process and FIGS. 3 and 5 show a multi-cycle process in which several strokes are used.

The upper part of Figs. 2 to 5 represent a time reference, on which different steps are performed. The lower part of the figure contains a diagram showing the change of some parameters during the process. The pressure parameter is the atmospheric pressure in the mold.

In the process shown in FIGS. 2 and 3, particulate material is first filled in the mold. It reaches below atmospheric pressure and the material is shaped by the ram during the preforming step. During the delay, the ram is removed and then the preformed material is forged dynamically by striking once or several times with the impact ram. In this case the material is a resistance heated during the stroke, and the applied current is synchronized with the triggering of the impact. Optionally, after being molded into an additional preformed ram, the vacuum is released and the resulting component is pressed.

In the process shown in FIGS. 4 and 5, subatmospheric pressure is reached and the material is shaped by the ram during the preforming step. The ram is maintained while pressing the particles during the subsequent steps. Vibration of the particulate material is used during the preforming. As in Figures 2 and 3 the material is heated by the current during shocking. The pressure from the preformed ram is maintained even after shock for energy retention, the vacuum is released and the components obtained are pressed.

In the above embodiments the preformed mold is the same as the mold. In addition, the material from which the body is formed is formed in the form of particles. However, it is also possible to use solid materials. In this case it is not necessary to use preforms. Depending on the density of the solid material, the preforming step may be advantageous. After a possible preform, the solid material is shocked simultaneously by two opposing impact rams. The same steps as when forming the particulate material can be used.

Starting with the particulate material and the solid material, the formation process can be performed by using two opposing impact rams. In addition, at least two impact RAMs may be used, for example, to obtain an oblique deformation.

The preforming step may comprise one or more moldings. Since the particulate material is vibrated, only one molding may be required. However, several moldings can yield somewhat higher densities.

By using the preferred properties of the invention it is possible to obtain the same level of material properties as achieved by using forging or by using HIP or HIP + forging.

Modifiable properties within the definition of the process of the present invention are as follows.

1) The direction of the strike. It may be in one or more directions.

2) vibration. During the preforming step and / or during the forming step and / or the energy retention step.

3) number of preforms

4) spacing between preformed strokes

5) temperature during preforming

6) preforming pressure

7) The same parameters can be changed for the impact stage.

8) Impact stroke pressure and energy. It may be the same or different for different strokes.

9) Subsequent molding may or may not be used in one or more steps.

10) Atmospheric pressure in the mold. It may or may not be reduced.

11) Use of gases other than air. For example inert gas or reactive gas.

12) The temperature of the mold and the material. It may be increased, in some cases reduced or may be at ambient temperature.

13) The material to be formed may be particles such as powders, pellets, grains or the like or solids.

14) Current may or may not be used.

15) The vibration can be varied with respect to amplitude, frequency, or direction, and can be vertical and / or horizontal.

16) The preform mold and the molding mold may be the same or may be different.

17) The number of steps can be changed. Some steps may be repeated several times after repeating the previous steps, after which preform or molding may be filled with more material and then the preforming and / or molding may be repeated.

18) The relationship between the mass of the impact ram, the mass of the punch, or the mass of the material to be formed may vary.

19) Energy retention may or may not be used.

The mass m of the strike unit must be greater than the mass of the substance. Thereby, the demand for the high impact speed of the strike unit can be somewhat reduced. When the striking unit strikes the material, this causes local coalescing and thus the resulting deformation of the material. In any case, an increase in density is obtained. Waves or vibrations are generated in the material in the direction of impact, and these waves or vibrations have a high kinetic energy, activate the slip plane in the material and also cause relative displacement of the grain of the powder. The coalescence may be adiabatic coalescence. Local increases in temperature develop spot welding (interparticle melting) in the material and increase density.

Preforming is a very important step. This is done to vent the air and to orient the particles in the material. The preforming step is slower than the forming step and therefore easier to vent air. This can also be made easier by using vibrations during or before the preform. A very fast forming step does not have the same possibility of releasing air. Thus, air remaining even after preforming can be included in the produced body, which is a disadvantage. The preforming is carried out at a minimum pressure sufficient to obtain the maximum degree of packing of the particles resulting in the maximum contact surface between the particles. It is material dependent and depends on the softness and melting point of the material.

The preforming step in the example was performed by molding with an axial load of 117680N. This is done by preforming mold or final mold. In all embodiments where nothing is mentioned, the mold used is a cylindrical mold, which is part of the tool and has a circular cross section with a diameter of 30 mm. The area of this cross section is approximately 7 cm 2. This means that a pressure of approximately 1.7 × 10 ⁸ N / m 2 was used. The material may be preformed at a pressure of at least about 0.25 × 10 ⁸ N / m 2, preferably at a pressure of at least about 0.6 × 10 ⁸ N / m 2. The necessary or preferred preforming pressure used is material dependent and for some materials may be sufficient to mold at a pressure of about 2000 N / m 2. Other possible values are 1.0 × 10 ⁸ N / m 2 and 1.5 × 10 ⁸ N / m 2. Lower pressures may be used if vacuum or heated materials are used. The height of the cylindrical mold is 60 mm.

The forming stroke may release total energy corresponding to at least 100 Nm in the cylindrical tool described at air and at room temperature. Other total energy levels can be at least 300, 600, 1000, 1500, 2000, 2500, 3000, and 3500 Nm. Energy levels of at least 10000, 20000 Nm may be used. Some new machines have the ability to strike with 60000 Nm in one stroke. Of course such high values can be used. And if some such strike is used, the total amount of energy can reach several hundred thousand Nm. The energy level depends on the material used and on which application the body produced is used. Different energy levels for one material will give different relative densities of the body of material. The higher the energy level, the denser the material will be obtained. Different materials require different energy levels to achieve the same density. This depends, for example, on the degree of cure of the material and the melting point of the material.

The energy level needs to be corrected and applied depending on the shape and structure of the mold. For example, if the mold is spherical, different energy levels will be required. One skilled in the art will be able to test what energy level is required for a particular mold. The energy level depends on what the body is used for, i.e. what relative density is needed, and on the geometry of the mold and the properties of the material. The striking unit must release sufficient kinetic energy to form a body when striking the material inserted into the molding mold. With higher stroke speeds, more vibration, increased friction between particles, increased local heat, and increased interparticle melting of the material are achieved. The larger the stroke area, the more vibration is obtained. There is a limit that more energy will be delivered to the tool rather than the material. There is therefore also an optimum for the height of the material.

The more shaped the material is by the coalescence technique, the smoother the surface is obtained. The porosity and the surface of the material are affected by the method. If a porous surface or body is desired, the less porous surface or body should not be shaped to the extent required.

What was described above for energy conversion and wave generation also applies to solid bodies. The solid body in the present invention is the body when the target density for a particular application is achieved.

To give the energy level required for the impact, the strike unit preferably has a speed of at least 0.1 m / s or at least 1.5 m / s during the stroke. Lower speeds may be used than in the prior art. The speed depends on the weight of the strike unit and what energy is required. The total energy level in the forming step is at least about 100 to 4000 Nm. However, higher energy levels may be used. Total energy means energy levels for all strokes added together. The striking unit produces at least one stroke or a plurality of consecutive strokes. The interval between strokes according to the embodiment is 0.4 and 0.8 seconds. For example at least two strikes may be used.

The method also includes preforming the material at least twice. It is shown in the examples that this can be an advantage in order to obtain high relative densities over strokes using the same total energy and only one preform. Two moldings provide about 1-5% higher density than one preforming depending on the material used. This increase may be higher for some materials. When the preforming is done twice, the forming step is performed at small intervals between times such as about 5 seconds. Approximately the same pressure can be used for the second preform.

In addition, the method may also include molding the material at least once after the compacting step. This has been known to produce very good results. Subsequent moldings should be carried out at a preforming pressure, ie at least equal to 2000 N / m ² . Another possible value is 1.0 × 10 ⁸ N / m ² . Higher subsequent molding pressures, such as twice the preforming pressure, are also preferred. Preform values should be tested for all materials. Subsequent moldings affect the sample differently than preforming. The transmitted energy that increases the local temperature between the powder particles from the stroke is preserved for a long time, and can affect the sample to harden for a long time after the stroke. Energy is maintained in the solid body produced. Perhaps the "lifetime" for the material wave of the sample cold is increased to affect the sample for a long time and more particles can melt together. The result is an increase in the density of the produced body of about 1-4%, which is also material dependent.

When using preforming and / or subsequent molding, lighter strokes and higher pre and / or subsequent molding can be used, which saves equipment since lower energy levels can be used. This depends on the purpose of use and the materials used. It may also be a method with a higher relative density.

In order to obtain an improved relative density, the material may be pretreated before the treatment. The powder may for example be preheated to ˜50-300 ° C. or higher temperature depending on the type of material being preheated. The powder may be preheated to a temperature close to the melting point of the material. Suitable methods of preheating can be used, such as general heating of the powder in an oven. Vacuum or inert gases can be used to obtain more dense material during the preforming step. This will have the effect that air is not contained in the material as much during the process.

The polymer may be mixed homogeneously with the additive before treatment.

The body will be heated and / or sintered at some point after compression or subsequent molding in accordance with another embodiment of the present invention.

Common post-processing steps are:

The body produced is a green body and the method may further comprise sintering the green body. The green body of the present invention produces a fully tight body without the use of other additives. Thus, the green body can be stored, handled, for example, and also processed, such as for example grinding or cutting, of unfinished bodies. Green bodies can also be used as final products without intermediate sintering. This is when the body is a bone graft or replacement in which the graft must dissolve in the bone.

It has previously been known that superior results are obtained with particles having an irregular particle structure. The particle size distribution will probably be wide. Small particles will fill the voids between the large particles.

Particulate materials include lubricants and / or sintering aids. Lubricants are useful for mixing materials. Sometimes the material requires a lubricant in the mold to easily remove the body. In some cases this may be optional if a lubricant is used in the material. This will make it easier to remove the body from the mold.

Lubricants cool material particles, fill spaces and smooth them. This is both an advantage and a disadvantage.

Internal lubrication is good. This is because particles can easily slide in space and shape the body to a higher degree. This is useful for pure molding. Internal lubrication reduces the spacing between particles, releasing less energy and reducing interparticle melting. Compression is not good at obtaining higher densities and the lubricant must be removed, for example by sintering.

External lubrication increases the amount of energy delivered to the material and indirectly reduces the load on the tool. The result is more vibration, increased energy, and a greater degree of interparticle melting in the material. Less material adheres to the mold and the body is easily extruded. This is useful for molding and compression.

An example of a lubricant is Accrawax C, but other known lubricants may be used. If the material is to be used in a medical body, the lubricant must be medically acceptable or removable during processing.

Grinding and cleaning of the mold can be omitted if the tool is smooth and the powder is preheated.

In some cases, it is necessary to use a lubricant in the mold to easily remove the body. It is also possible to use a coating in the mold. The coating consists of for example TiNA1 or Balinit Hardlube. If the tool has an optimal coating, the material will not stick to the tool portion and will not consume some of the delivered energy, which increases the energy delivered to the powder. If it is difficult to remove the formed body, it will require time-consuming lubrication.

For example, about once per six strokes may be used. The energy level is the same for all strokes, and the energy can be increased or decreased. The stroke set starts with at least two strokes of the same level and the last stroke has twice the energy. The reverse is also possible.

The highest density can be obtained by transferring the total energy in one stroke. If the same total energy is delivered in multiple strokes, a lower relative density is obtained, but the tool is preserved. Multiple strokes can therefore be used in applications where maximum relative density is not required. However, multiple strokes can produce the same density as one stroke if the time interval between strokes is extremely short.

Through a series of short impacts, the body of material is continuously supplied with static energy which contributes to keeping the traveling wave forward and back active. This supports the generation of further deformation of the material at the same time as the new impact will produce some more permanent deformation of the material.

According to another embodiment of the invention, in addition to the strike unit hitting the material body, the impulse decreases for each stroke in a series of strokes. Preferably the difference between the first stroke and the second stroke is large. It will be easier to make the second stroke with an impulse smaller than the first impulse for such a short period (preferably about 1 ms), for example by an effective reduction of the recoil strike. However, it is possible to apply a larger impulse than the first or preceding stroke if necessary.

If the material inserted into the mold is fused, a hard, smooth and dense surface is obtained on the formed body. This is an important characteristic of the body. Hard surfaces provide the body with excellent mechanical properties such as high wear and scratch resistance. Smooth and dense surfaces make the material resistant to corrosion, for example. The less pores, the greater the strength obtained in the product. This refers to both open pores and the total amount of pores. In conventional methods, the goal is to reduce the amount of open pores because it is impossible to reduce the open pores by sintering. It is important to mix the powder mixture until it is as homogeneous as possible to obtain a body with optimal properties.

The coating can be prepared according to the method of the present invention. When manufacturing a coated device, the device is placed in a mold and can be fixed in a conventional manner. The coating material is inserted around the device to be coded in the mold, for example with gas automation, after which the coding is formed by fusion. The device to be coated may be a material formed according to the present application, and may be a device formed by conventional methods. Such coatings are very beneficial because they can provide specific properties of the device.

The coating can be applied by conventional methods such as dip coating and spray coating to the body produced according to the invention.

It is also possible to first compress the material by at least one stroke in the first mold. The material can then be transferred to another large mold and additional polymeric material can be inserted into the mold and compressed onto the top or side of the first compressed material by at least one stroke. Many other combinations are possible depending on the energy of the stroke and the choice of material.

The present invention relates to a product obtained by the method described above.

By the use of the current process it is possible to produce a large body of one piece. It is often necessary to produce the desired body in several pieces that must be joined together before use in the currently used processes associated with casting. These pieces can be joined using, for example, screws, adhesives, or a combination thereof.

A further advantage is that the method of the present invention can be used for powders that carry charges that repel particles without treating the powders to neutralize the charges. This process can be carried out irrespective of the electrical charge or the surface tension of the powder particles. However, this does not preclude the use of additional powders or additives that carry opposite charges. It is possible to control the surface tension of the body produced by the use of the present invention. In some cases, low surface tensions are desirable, such as wear ring surfaces that require an oil film, while in other cases high surface tensions are desirable.

Some examples illustrating the invention are described below.

The examples illustrate how different parameters can be changed to increase the relative density of the metal, ceramic and polymer samples described and processed according to the present process. Stainless steel is the material tested in all studies except powder height, theoretical density, powder hardness and melting temperature studies. See Table 1 for technical data on the stainless steels used.

The dimension of the sample is the same for all studies except for the collision area study where two sample dimensions were used.

Technical data of stainless steel characteristic Stainless steel 316L 1. Particle size (microns) <150 2. Particle Distribution (microns) 0.60wt%> 15042.70% <45 3. Particle Form irregular 4. powder production Water Automation 5. Crystal Structure FCC 6. Theoretical Density (g / cm ³ ) 7.90 7. Apparent Density (g / cm ³ ) 2.64 8. Melting temperature (℃) 1427 9. Sintering temperature (℃) 1315 10. Hardness (HV) 160-190

The sample produced was in the form of a disc with a diameter of 30.0 mm and a height of 5-10 mm. The height depends on the relative density obtained. If 100% relative density is obtained, the thickness is 5.00 mm.

Holes with a diameter of 30.00 mm are drilled in the molding die (part of the tool). The height is 60mm. Two stamps are used (also part of the tool). The bottom stamp is located at the bottom of the molding die. The powder is filled in a cavity formed between the molding die and the lower stamp. Thus, the impact stamp is located on top of the molding die and the stroke can be performed.

Example

1. powder height research

Metal, ceramic and polymer powders are tested in powder height studies. Powders used are stainless steel, hydroxyapatite and UHMWPE. See Table 2 for the properties of the powders tested.

Technical data for powders tested in powder height studies characteristic Stainless steel316L Hydroxyapatite UHMWPE 1. Particle size (microns) <150 <1 <150 2. Particle Distribution (micron) 0.60wt%> 15042.70wt% <45 <1 - 3. Particle form irregular irregular irregular 4. powder production Water Automation Wet Chemistry Precipitation - 5. Crystal Structure  FCC Apatite 50% amorphous 6. Theoretical Density (g / cm ³ ) 7.90 3.15g / cm ³ 0.94 7. Apparent Density (g / cm ³ ) 2.64 0.6 50 8. Melting temperature (℃) 1427 1600 125 9. Sintering temperature (℃) 1315 900 - 10. Hardness 160-190HV 450HV R50-70 (Rockwell)

metal

6 and 7 show the relative density as a function of the total impact energy and the impact energy per mass, respectively, for samples treated with different powder masses. All samples were tested in the same cylindrical mold but at different powder heights and thus different masses. The reference mass is 28 g.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter Stainless steel Collision area calendar Reference mass 28 g

result

The results show that to reach the same density, a body with a larger powder height, and therefore a higher mass, requires less energy per mass than a body with a smaller powder height. Roughly, the same total energy is needed to achieve the same density regardless of powder mass or height.

ceramic

8 and 9 show the relative density as a function of the total impact energy and impact energy per mass, respectively, for ceramic samples treated with different powder masses. All samples were tested in the same cylindrical mold but at different powder heights and thus different masses. The reference mass is 11.1 g.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter Hydroxyapatite Collision area calendar Reference mass 11.1 g

result

8 shows that the three curves follow each other, meaning that some density is obtained regardless of the shape of the sample for impact energy per weight. This is also shown in FIG. 9 where density is plotted as a function of total impact energy. The curve shifted left on the diagram for low sample mass. It can be seen that higher densities for 11.1 g do not reach stagnant densities as indicated for 2.8 g and 5.5 g samples. The results show that the mass of the sample and the height of the powder in the mold affect the density in relation to the overall impact energy. That is, larger sample masses require more energy to achieve some density. The results also show that as shown in Figure 8, the impact energy per mass has a linear relationship between density and mass up to at least 271 Nm / g.

polymer

10 and 11 show the relative densities as a function of the total impact energy and the impact energy per mass, respectively, for polymer samples treated with different powder masses. All samples were tested in the same cylindrical mold but at different powder heights and thus different masses. Reference mass is 4.2g

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter UHMWPE Collision area calendar Reference mass 4.2g

result

The lower mass curve shifted to the right or higher energy in the density energy graph. Movement towards lower densities was observed for smaller sample masses.

10 shows that higher density is obtained when the powder height is increased for a given impact energy per mass. Thus, the maximum density is reached at lower impact energy per mass for heavy samples. By studying the individual density-energy graphs, it can be divided into three phases. Phase 1 may be specified as a compressed phase, phase 2 may be specified as a stationary phase, and phase 3 may be specified as a reaction phase. In the compressed phase, the density-energy curve follows an initial high compression rate and logarithmic relationship. The slope decreases with increasing energy and eventually the curve reaches a plateau. The stagnant phase is characterized by almost constant gradient and constant density. At some energy level, density begins to increase again. This part of the curve is nonlinear with increasing derivative of the initial amount. The curve derivative eventually decays, and the curve asymptotically reaches 100% relative density. Phase 1 and phase 2 can be seen in the metal control. The samples of phase 1 and phase 2 are characterized by their transparent and brittle properties. Entering phase 3, the sample gradually changes its properties. New material states first occur at the outer edges and top and bottom and end at the surface. This material state is specified as being stronger, transparent and with a plastic and thick surface texture. For smaller mass samples, the reaction does not occur gradually and is direct. In phase 3 the process can be described as a rather dramatic and small explosion. Immediately after the impact stroke, white smoke is observed coming from the sample and the material is released from between the stamp and the molding die. In addition, the pressure occurring in the reaction phase turned out to be very high when the molding die broke open during one test. Larger weight samples are found to be more compact at lower energy per mass levels, and for small samples, reaction shifts of the material state occur rather than directly. The limited test set of 12.8 g is due to the limited powder column height of the tool. The insertion distance was smaller than the predetermined distance of 30 mm (diameter of the stamp). The test thus had to stop at an impact energy of 2100 Nm to eliminate tool failure. At densities for 8.4 g samples the two dents do not stay together and depend on the sample coming out as a powder.

conclusion

The same density was obtained with the same impact energy per mass, regardless of powder height or mass, for the ceramic powder treated according to the invention. In contrast, for the metal and polymer powders treated according to the invention, the same density was obtained with the same overall impact energy regardless of the powder height or mass.

2. Collision Area

12 and 13 show the relative impact as a function of total impact energy and impact energy, respectively, for samples with different impact surface areas.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter Stainless steel Mass (m) M2 / M1 = 25 Collision Surface Area (S) S2 / S1 = 8

result

The curve shows a linear relationship between the impact surface area, shock energy and pressure. Samples with different diameters will reach the same density if they are treated with the same impact energy per mass.

3. Shrink

FIG. 14 shows the relative density as a function of shrinkage in% volume for samples treated according to the present invention as compared to samples treated with conventional powder metallurgy (PM). All samples were sintered separately after the shocking and pressing step. 15 shows a comparison between the density obtained after sintering for samples treated according to the invention (DFIER) and for samples treated by conventional methods, respectively.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter Stainless steel Substance additives Internal Lubricant (1.0wt% Accrawax) After treatment Sintered

result

Samples treated by Method X reach higher densities than conventional PM treated samples. If the sample is sintered after the forming step, the material shrinks due to the internal voids of the material. Shrinkage of the material negatively affects the structural and mechanical properties of the final product.

The curve in FIG. 14 shows that shrinkage volume decreases as the relative density increases for all samples. Samples treated with DFIER shrink more than samples treated with conventional methods. The reason is probably that the samples treated with DFIER have better directivity of the particles and the energy delivered during the shocking state is stored at the grain boundaries and released during sintering. Free energy increases the driving force to solidify the material and collapse the voids during sintering. Samples pressed by conventional methods have less driving force during sintering compared to samples treated with DFIER.

Samples treated with DFIER have a higher raw density prior to sintering, which means less material shrinks and thus better mechanical properties are acquired compared to samples molded using conventional pressurization. Samples with low raw densities require complex and expensive sintering to remove all voids in the material. The high raw density of the sample treated with DFIER makes it possible to use an inexpensive and easy sintering process to reach full density.

4. Speed research

FIG. 16 shows relative density as a function of impact energy for samples shocked at different impact rates of impact ram. Impact speeds for impact ram and punch are shown in FIGS. 17, 18 and 19, respectively. 20 shows the obtained impact velocity of the punch for different impact ram masses for maximum use shock energy, 3000 Nm for all velocity studies.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve none matter Stainless steel Impact speed of impact ram (m / s) V7 <V6 <... <V1 Impact Speed of Punch (m / s) 7> VP6> ..> VP1 Momentum Equation mpact ram * V = Mpunch * VP

result

The curve in FIG. 16 shows that the low impact speed of the impact ram reaches the highest density for a particular shock energy fastest.

The difference between the maximum densities for the seven series run is 10 percent. The results indicate that higher densities are obtained when the impact ram mass is increased or equal to the reduced impact rate for a given energy level per mass. The result decreases with increasing energy. The relative density in the preform is largely dependent on the static pressure.

The mass of the impact ram determines the impact speed of the punch, which is the speed at which the powder is accelerated. The high impact ram mass will accelerate the light punch at a higher speed compared to the impact ram with the lower mass. 18 and 19 show that the highest impact speed is obtained for punches accelerated by the highest and lowest impact rams.

The diagram shows that the impact speed of the ram reaches 0 m / s as the impact ram's mass increases indefinitely, which means that there is a limit to how many impact rams can be used to achieve high punch speeds.

The relationship between the punch and impact ram mass to reach the highest density was 1: 3846 in this study.

The material used in the tool, as well as the material composition of the tool and the powder processed, must be considered to find the optimal mass relationship between the impact ram and the punch.

5. Multiple Shock Studies 1

FIG. 21 shows the relative density as a function of the number of shocks for the sample treated with the total shock energies of 3000 Nm and 4000 Nm, respectively.

Condition pressure Waiting Temperature Room temperature Energy reserve furnace material Stainless steel Full shock energy Schedule for each study

result

The curve in the diagram shows that the highest density is reached for the sample treated as one single shock, compared to the sample treated with the same total energy executed in multiple shock series.

We can note that the distance between the curves increases as the number of strokes increases.

6. Multiple shocks-study 2

Figure 22 shows the relative density as a function of the number of shocks. Four studies were conducted. In each study, the samples were treated with multiple shocks or multiple shocks with a constant energy per shock.

Condition pressure Waiting Temperature Room temperature Energy reserve furnace material Stainless steel Full shock energy Schedule for each study

result

The curve for the sample treated with the highest energy per shock increases most rapidly at a higher density compared to the sample treated with the lower energy per shock. This curve shows that high density is reached for a shock energy of 50 Nm per shock, which means that there is a lower limit to the energy per shock when the total energy is divided into a plurality of shocks.

7. heating research

Condition pressure Waiting Temperature Room temperature Energy reserve furnace material Stainless steel Heating temperature 150 ℃

result

Samples treated at temperatures above room temperature reach a density of nearly 100%. This curve increases faster with higher density compared to the curve showing density results for samples treated at room temperature.

Heating of the powder before and during DFIER treatment increases the initial energy state of the powder. Thus, powder compacting starts from a higher temperature level and results in a higher final density. This means that less energy is needed to reach sufficiently high temperatures in the material to achieve spot welding between powder particles during the shock phase.

Heating the stainless steel powder to 150 ° C. can result in a relative density improvement of ˜2%.

The material properties of the treated powder must be taken into account to find the optimal parameter value for heating.

An electric current can be used to heat the powder during the DFIER.

8. Vacuum Research

FIG. 24 shows relative density as a function of impact energy per mass for samples treated in vacuo.

Condition pressure vacuum Temperature Room temperature Energy reserve furnace material Stainless steel vacuum -100 Pa

result

The curve for the sample treated in vacuo increases faster and the sample reaches a higher density than the sample treated at atmospheric pressure.

When the pressure is reduced between the powder particles, the reactivity is increased in the material and spot welding is achieved with lower processing energy compared to the powder treated at atmospheric pressure.

Samples that are compacted in air have a pore filled with air. If such sample is sintered after DFIER, heating during sintering will expand the air in the closed pore to expand the material. If this pore is at a lower pressure, ie vacuum or quasi-vacuum, the pore will not expand and instead will collapse during sintering and a density of 100% can be obtained.

The material properties of the powder to be treated must be taken into account in order to find the optimal parameter values for processing in vacuum.

9. Impact direction

FIG. 25 shows relative density as a function of impact energy per mass for samples processed in one or two impact directions.

Condition pressure Waiting Temperature Room temperature Energy reserve furnace material Stainless steel

result

Samples processed by impacting in two directions increase in density faster and reach higher densities compared to samples processed in one impact direction for the same energy. This is because powders treated from two directions get a better orientation of the powder particles during DFIER as compared to powders treated from one direction. Good orientation of the powder particles facilitates the solidification process.

The material properties of the treated powder must be taken into account in order to find the optimal parameter values for treating the powder with two impact directions.

10. Time interval study

FIG. 26 shows the relative density as a function of the time interval between two successive shocks. All samples were shocked twice with different time delay between shocks.

Condition pressure Waiting Temperature Room temperature Energy reserve furnace material Stainless steel Shock energy per stroke 800 Nm Number of shocks 2

result

The curve shows that the time delay between the two shocks must be very short in order to properly affect the material.

The optimum time delay between the two shocks depends on the mechanical properties of the treated material. Important material properties to consider are thermal conductivity and sound velocity.

11. Energy Reserve Research 1

FIG. 27 shows relative density as a function of impact energy per mass for shocked samples compared to samples that are post compacted and shocked by energy retention.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve Yes material Stainless steel

result

The curve showing the results for the shocked and post compacted sample only increases faster and reaches a higher density compared to the curve for the shocked sample.

As a result of using the energy retention step, the energy delivered during the shocking phase is retained in the material, affecting the sample and increasing the metal bond and spot welding between the powder particles. Thus, it is possible to increase the relative density by almost 100% by using a post compacting step.

The material properties of the treated powder must be considered in order to find the optimal parameter value for energy retention.

12. Energy Reserve Study 2

FIG. 28 shows relative density as a function of impact energy per mass for samples treated with different time delays between start and shock of energy reclamation.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve Yes material Stainless steel

result

The curve for the sample treated as a direct start of energy retention after the shock phase increases fastest and reaches the highest relative density. This curve shows that the time between the shock process and energy retention should be less than 1 s to get the maximum effect. Energy reserves have a smaller effect if the time delay between shock and energy reserves increases.

The duration of the local increase in temperature between the powder particles after the shock phase is very short. The condition for achieving the effect of energy retention is that the sample is still in an increased energy state, not when the sample is already cooled to room temperature. The material properties of the powder to be treated must be taken into account in order to find the optimal parameter values for energy retention.

13. Energy Reserve Research 3

29 shows relative density as a function of energy retention time for shocked and post compacted samples. The curve shows the effect of sustaining energy retention.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve Yes material Stainless steel

result

The curve shows that the effect of reducing energy retention decreases after a few seconds. The optimal time for energy retention depends on the nature of the treated material, in combination with the sample size. Larger masses will retain heat for longer periods of time, so it is possible to increase energy retention and still benefit.

14. Preformation Study 1

Condition pressure Atmospheric pressure Temperature Room temperature material Stainless steel

result

The curve shows that increasing the preforming pressure increases the density of the preformed sample.

The preforming pressure on the sample before the shock phase is an important parameter to consider because the green density of the sample will affect the final material properties achieved after the complete DFIER process.

15. Preform Study 2

Figure 31 shows relative density as a function of preforming pressure. The curve shows the effect of preforming at different ambient pressures.

Condition pressure Atmospheric pressure: (P = 1) 2. Vacuum: (P = 0) Temperature Room temperature material Stainless steel

result

The curve for the sample preformed in vacuo reaches the highest density.

Instead, the energy needed to remove air from the powder in the preform at normal pressure and overcome the atmospheric pressure can directly affect the powder in the preform in vacuum.

16. Preform Study 3

32 shows the relative density as a function of impact energy per mass. The samples were preformed differently by varying the duration of the preform phase.

Condition pressure Atmospheric pressure Temperature Room temperature material Stainless steel

result

The curve indicates that higher density is reached if the sample is preformed for longer than 1 s.

The material properties of the treated powder must be taken into account to find the optimal parameter values for the preforming step.

Characteristic study

Three characterization studies were performed: density study, powder hardness study and melt temperature study. Powder properties for the powders are described in Table 21 and Table 22.

Powder Properties for Metals Used in Characterization Studies characteristic Ti-6A1-4V titanium Co-28Cr-6Mo Al-alloy Ni-alloy 1. Particle size (microns) <150 <150 <150 <150 <150 2. Particle Distribution (microns) 2wt%> 150 Balance <150 0.1wt%> 2503wt%> 2005wt%> 1605-20wt%> 10020-35wt%> 6310-25wt%> 4535 50wt% <45 6.57wt%> 12550.80wt%> 10624.25wt%> 10012.26wt%> 906.12wt% <90 3. Particle Tissue irregular irregular irregular irregular irregular 4. produce powder Sign Language Water Automation Water Automation Water Automation 5. Crystal Structure Al Stabilizes HCP V Stabilizes BCC HCP 85% alpha phase 15% carbide FCC FCC 6. Theoretical Density (g / cm ³ ) 4.42 4.5 8.5 2.66 8.38 7. Apparent Density (g / cm ³ ) 1.77 1.80 3.4 1.22 2.59 8. Melting point (℃) 1600-1650 1660 1350-1450 658 1645 9. Sintering point (℃) 1260 1000 1200 600 1315 10. Hardness (HV) - 60 460-830 50-100 80-200

Table 21 continued

characteristic Stainless steel Low mild steel Martensitic River Tool steel 1. Particle size (microns) <150 <150 <150 <150 2. Particle Distribution (microns) 0.60wt%> 15042.70wt% <45 3.2wt%> 25079.5wt% <150 1.06wt%> 1504.32wt%> 12512.03wt%> 10623.59wt%> 7519.26wt%> 539.04wt%> 4535.70wt% <45 0.4wt% 150-18024.48wt% 106-15026.68wt% 75-10628.67wt% 45-7519.77wt% <45 3. Particle Tissue irregular irregular irregular irregular 4. produce powder Water Automation Water Automation Water Automation Water Automation 5. Crystal Structure FCC BCC <900 ℃ FCC> 900 ℃ FCC BCC <910 ℃ FCC> 910 ℃ 6. Theoretical Density (g / cm ³ ) 7.90 7.75 7.73 7.75 7. Apparent Density (g / cm ³ ) 2.64 2.87 3.37 2.55 8. Melting point (℃) 1427 1540 1427 1350-1450 9. Sintering point (℃) 1315 1230 1230 1315 10. Hardness (HV) 160-190 130-280 180-330 207-241

Powder Properties for Ceramics Used in Characterization Studies characteristic Silicon nitride Hydroxyapatite Alumina Zirconia 1. Particle size (microns) <0.5 <1 <0.5 0.4 2. Particle Distribution (microns) <0.5 <1 0.3-0.5 <0.6 3. Particle Tissue irregular irregular irregular irregular 4. produce powder Lyophilized Granulation Wet chemical precipitation Grinding Freeze Dry Granulation Spray dry granulation 5. Crystal Structure 98% alpha 2% beta (hexagonal) Apatite Alpha Tetragonal 6. Theoretical Density (g / cm ³ ) 3.18 (batch 1, 2) 3.27 (batch 3) 3.12 (batch 4) 3.15g / cm ³ 3.98 (batch 1) 3.79 (batch 2) 3.98 (batch 3) 3.79 (batch 4) 6.07 7. Apparent Density (g / cm ³ ) 0.38 0.6 0.5-0.8 - 8. Melting point (℃) 1800 1600 2050 2500-2600 9. Sintering point (℃) 1820 900 1600-1650 1500 10. Hardness (HV) 1570 450 1770 1250-1350

17. Theoretical Density Study

33 shows the maximum obtained relative density as a theoretical density function for the other metal powders.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve radish metal Metal powder (see table 3)

conclusion

It can be seen from the diagram that metal powders having a high theoretical density are more difficult to treat at high density by DFIER compared to metal powders having a low theoretical density. In Table 1 the materials used in the study are listed with the theoretical density and the relative density obtained for each material.

It is clear that many parameters are included to determine whether the material is easy to process at high density by the DFIER. Other important powder properties are powder type, alloy element, powder hardness, melting point, particle size and particle structure.

18. Powder Hardness Research

34 shows the maximum obtained relative density as a function of powder hardness for different ceramic and metal powders, respectively.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve radish metal Metallic powder (see Table 3) Ceramic powder (see Table 4)

conclusion

The plot shows that it is more difficult to treat hard powders at higher density than soft powders using DFIER. The test value for the metal powder shown has a small slope relative to the value for the ceramic material. This is because the divergence (400 HV, 70.6%) for ceramic materials is water-based ceramics. This means low powder hardness.

Hard metal or ceramic powders can be processed under vacuum and increased ambient temperature to reach higher densities.

19. Melting Point Studies

35 shows the maximum relative density obtained as a function of melting point for different metal and ceramic powders, respectively.

Condition pressure Atmospheric pressure Temperature Room temperature Energy reserve radish

conclusion

The metal curve shows no clear relationship between the melting point for the metal and its ease of processing at high density with DFIER. Table 26 shows two steels having the same melting point but different powder hardness, which means that one metal property alone cannot determine whether the metal is easy to treat at high density by the DFIER.

Substance type Powder Hardness (HV) Melting Point (℃) Stainless steel 160-190 1427 Martensite River 180-330 1427

Ceramic powders have a higher melting point and are more difficult to treat at higher density than metal powders, which is shown in FIG. 35.

20. Vibration forming study

FIG. 36 shows the relative density as a function of pressure applied to a sample treated by conventional static forming relative to a sample treated by vibration forming (VC) in combination with other processes.

Condition Absin Atmospheric pressure Temperature Room temperature matter Stainless steel Vibration speed 233 oscillation / s Shock energy 300-3000Nm

result

The curve shows that the relative density of the powder vibrated under controlled conditions while in combination with static pressure or / and shock energy is much higher than the sample treated with static pressure alone.

Samples shocked from two directions and by biaxial static pressure, formed by vibratory molding, reach the highest density for the lowest overall pressure.

Claims (19)

In a method of producing a body at a higher density from particulate matter by coalescence or molding, a) filling the preform mold with materials in the form of powder, pellets, grains, etc., b) vibrating the mold, c) preforming the material at least once by preforming means, and d) a striking unit when striking the material inserted into the molding mold by a striking means, comprising molding the material in the molding mold by at least one stroke and coalescing the material into a higher density. Releasing sufficient kinetic energy to form the body. The method of claim 1 wherein the preformed mold and the molding mold are the same mold. The method according to claim 1 or 2, wherein the preforming step c) is performed while vibrating the mold. The method according to any one of claims 1 to 3, d) the material is molded from two opposing sides using two striking units at the same time.  In a method of producing a body at a higher density from a solid material by coalescence or molding, a) inserting said solid material into a mold, c) possibly preforming said material at least once by preforming means, and d) by means of at least one stroke simultaneously from two sides, using two strike units which release sufficient kinetic energy to form the body when striking the material, which coalesces the material or at a higher density; Shaping said material in a mold. 6. The method of claim 1, wherein the material is molded from two opposing sides and at least one other side using at least three striking units simultaneously. 7. 7. A method according to any one of claims 2 to 6, characterized in that the preforming means is continuously applied to the material by the same or higher pressure during the forming step d) by the striking unit or units. Way. 8. The molding according to any one of claims 1 to 7, wherein the energy of the forming step d) is formed by e) holding or reapplying the strike means to pressurize the shaped material after the stroke or strokes. Characterized in that it is retained in the material. 9. A method according to any one of the preceding claims, wherein the temperature of the material in the mold increases or decreases during one or more steps. 10. The method of claim 9, wherein the material in the mold is heated before and / or during the preform c). The method of claim 9 or 10, wherein the material in the mold is heated before and / or during the forming step d). 12. The method of claim 10 or 11, wherein the material in the mold is heated using a current. 13. The method of claim 12, wherein flowing the current occurs concurrently with the preform c) and / or the forming stroke or strokes d). 14. A method according to any one of claims 1 to 13, wherein the material in the mold is placed at a pressure below atmospheric pressure before the preforming c). The method of claim 1, wherein the material in the mold or molds is held in another gas other than air. The method of claim 15, wherein the gas is an inert gas. The method of claim 15, wherein the gas is a reactive gas. 18. The method according to any one of the preceding claims, wherein the vibration b) is held during the forming d) and / or the energy retention e). A body produced by the method according to any one of claims 1 to 18.