Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/30—Feeding material to presses
  • B30B15/302—Feeding material in particulate or plastic state to moulding presses
  • B30B15/304—Feeding material in particulate or plastic state to moulding presses by using feed frames or shoes with relative movement with regard to the mould or moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
  • B30B11/02—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space
  • B30B11/022—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space whereby the material is subjected to vibrations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B5/00—Presses characterised by the use of pressing means other than those mentioned in the preceding groups

Definitions

• the invention relates to a method for the metered filling of the hatch openings of a press matrix with granulate made of sinterable, with volume contraction sintering powder in a uniform filling density, in which the die openings from a granule storage container are given predetermined amounts of granulate which exceed the volume of the die openings in which the excess amounts of granulate are then drawn off via the die openings.
• the compacts are made of sintered metal powder, hard metal powder, ceramics powder for the production of components for the most diverse applications, such as sealing and sliding rings, capacitors, substrates, insulating parts in electronic electrodes, etc., pressed. It is important in the production of the compacts regardless of the type of pressing process and regardless of the type of filling process that the die openings of the press matrix are filled with metered amounts of granules.
• a method for the metered filling of the matrix openings of a press matrix is known from DE-OS 24 00 791.
• a compact produced has a bulk density (weight / o lumen) which is less than the density of the individual granules.
• the compression of the granulate to form the shaped body depends on many factors, such as the particle size distribution in the granulate, the friction ratio in the press granulate (which depends on the properties of the binder and lubricants added), the type of granulate, the structure, the material , the surface procurement and the geometry of the press tools
• the degree of compression is given either as an absolute value (g / cm 3 ) or as a percentage of the theoretical density, which can take values between 50% and 80%.
• the compact is subjected to a heat treatment at such high temperatures that physical and / or chemical processes take place between the granules, the grains come closer to one another. This process is called sintering. In any case, the volume is reduced. For a certain material and given sintering conditions, this contraction, known as shrinkage, essentially depends on the pressing density.
• the shrinkage is related to the density of the press in such a way that the more the compact is compacted, and the lower it is, and vice versa.
• the molded body produced from a sinterable material therefore has an achievable dimensional accuracy which is dependent on the shrinkage and therefore on the compression density.
• the compression density should not only remain constant within a series of compacts produced, but first of all also within the individual compact. If there are different press densities within a compact, deviations from the original geometric shape (warping) result as a result of the inevitable shrinkage or there are mechanical stresses in the compact which can lead to cracks.
• REPLACEMENT LEAF overall has a constant vibrating density in order to achieve a constant pressing density in the entire volume in the compact produced therefrom.
• This object is achieved according to the invention in that the quantities of granules supplied to the die openings are compressed by means of acoustic waves before being removed. With the acoustic waves, a vibration can be carried out in the granules without causing the press matrix or the device feeding the granules to vibrate.
• the method according to the invention can be implemented with a simple device, since only one generator for acoustic waves, e.g. a loudspeaker or the like, must be arranged over the die openings of the press matrix.
• This device can also be easily used in an existing system, e.g. described in DE-OS 24 00 791, retrofit. The large scattering range of the density between the bulk density and the vibrating density, which occurs without this vibration, is avoided. This leads to a high quality and accuracy of the moldings produced.
• the action of the acoustic waves is carried out on the pre-metered granules according to an embodiment such that the quantities of granules supplied to the die openings are subjected to acoustic waves during the filling of the matrix openings with granules and / or after filling with granules.
• the optimum in terms of the vibratory density can be achieved in that the frequency of the acoustic waves is selected as a function of the density and / or the grain size of the granules.
• the frequency of the acoustic waves is selected in the range from 50 Hz to 2000 Hz, in particular from 60 Hz to 250 Hz.
• REPLACEMENT BLA ⁇ One embodiment provides that the frequency of the acoustic waves is kept constant during the exposure.
• the vibration density can also be achieved by increasing and / or decreasing the frequency of the acoustic waves during exposure to a predetermined frequency range.
• a press table is shown at 10, which has an opening 11.
• the ram 12 is guided adjustable.
• the press die 12 assumes the position shown when the die opening 16 is filled, the top of the press table 10 and the press die 12 with the opening 11 delimiting the matrix opening 16 with a volume which is required for the compact to be produced.
• the matrix opening 16 also determines the shape of the molded body to be produced.
• the filling slide 13, which has an opening 14, can be moved on the press table 10.
• the filler sled 13 is provided with the opening 14 under the run-out opening of the granule storage container 17.
• the granulate 18 fills the opening 14 in the filler sled 13, as shown by the pre-metered amount 15, which shows when the filler sled 13 is moved to the left into the Matrix opening 16 arrives.
• the generator 19 for acoustic waves is located above the opening 14 of the filling sluice 13 and passes through the funnel 20 to the pre-metered amount 15 of the granulate 18 act.
• the pre-metered amount 15 of granules 18 has a volume that is greater than the volume of the matrix opening 16, which is limited by the opening 11 and the press ram 12. The acoustic waves bring in the pre-metered amount
• the frequency of the acoustic waves can be adapted to the flow properties of the granulate 18.
• the frequency is preferably selected in the range from 50 Hz to 2000 Hz. The choice of frequency takes into account the weight and / or the grain size of the granulate.
• the filling slit 13 is adjusted to the right again.
• the excess amount of the granules is drawn off over the matrix opening 16.
• the breakthrough 14 is located under the outlet opening of the granulate storage container
• the application of the pre-metered quantity 15 with the acoustic waves can take place during the filling and / or after the filling of the matrix opening 16.
• the frequency of the acoustic waves can remain constant or can be changed in an increasing and / or decreasing manner in a predetermined frequency range during the application.
• the press table can have several die openings that are filled at the same time.
• the acoustic waves are then fed to all die openings.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Powder Metallurgy (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=6336528

Family Applications (1)

Country Status (2)

Cited By (3)

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Citations (4)

Family Cites Families (3)

• 1987
  • 1987-09-22 DE DE19873731769 patent/DE3731769A1/de active Granted
• 1988
  • 1988-09-16 WO PCT/DE1988/000578 patent/WO1989002820A1/de unknown

Patent Citations (4)

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