Powder dispenser and method for dispensing powder inside cylindrical mold

Abstract

Components, systems, assemblies, and methods related thereto for dispensing powder in a mold (12) are described. These include: a bridge (14) removably mountable on the mold and spanning an interior (47) of the mold when the bridge (14) is mounted on the mold (12); a shaft support (24) connected to the bridge (14) wherein the height of the shaft support (24) is adjustable relative to the interior of the mold (12); a shaft (32) rotatably mounted to the shaft support (24) and movable with the shaft support (24) when the height of the shaft support (24) is adjusted. The shaft (32) includes blades (34) extending from a distal end of the shaft (32), where the height of the shaft support (24) is adjusted to place the blades (34) in contact with the powder, and the shaft (32) is rotated to spread the powder in the mold (12).

Description

Technical Field

[0001] This invention relates to the field of manufacturing parts by sintering powder in a heat-resistant stamping die assembly under uniaxial pressure, and more particularly to an apparatus for spreading ceramic powder in the die prior to sintering. Background Technology

[0002] Sintering is a process in which heat and, optionally, pressure are applied to particulate matter, such as powder, causing the particles to adhere to each other to form a solid mass, or sintered body. The particulate powder is typically placed in a mold that confines the particulate matter to the shape inside the mold. After sintering, the sintered body is removed from the mold and processed into its final shape.

[0003] When placing powder into a mold, it is desirable to ensure that the powder is distributed substantially evenly. If the powder is not evenly distributed, the resulting sintered body may not have a uniform density. This is thought to be due to the sintering pressure compacting the higher points (peaks) in the powder to a greater density than the lower points (valleys). This is particularly problematic for powders that do not flow uniformly and have areas that clump together, a characteristic more commonly encountered with nonmetallic powders that are not spherical in shape.

[0004] Furthermore, some sintered products are formed from different powder layers. One layer may be a high-strength support layer, while the outer layer is a corrosion-resistant and / or wear-resistant layer formed from different materials. It is desirable that the layers form uniformly to each other, so that the layer thickness in the resulting sintered body does not change significantly from one location to another. This is desirablely achieved by uniformly spreading the powder layers, resulting in a sintered body with layers of substantially uniform thickness.

[0005] Relevant background information (such as that found in the following background patents, patent publications, and non-patent documents (if any) (found in the appendix and whose entire text is incorporated herein by reference)) is disclosed for background purposes and in relation to the prior art only, but does not contain one or more elements of the present invention: for example, in U.S. Patent No. 10,807,194 B2, found in Appendix A. GB 828,725 describes the production of articles (such as ceramic articles) pressed from powder materials (such as clay dust) using a top mold and a bottom mold and curved blades mounted on a lifting tool. CN110227818 A relates to a layered powder laying apparatus for powder metallurgy gradient functional materials, wherein positioning pins in a scraper are used to uniformly distribute powder.

[0006] Therefore, there is a need for apparatus and methods to improve the distribution of powder in the mold to achieve greater consistency and uniformity in the resulting sintered body. Summary of the Invention

[0007] To meet these and other needs, and for their purposes, this disclosure relates to an apparatus and related methods for spreading powder in a mold.

[0008] In one aspect, this disclosure describes an apparatus for spreading powder in a cylindrical mold having an interior having a bottom, a central axis, and an interior diameter. The apparatus includes: a bridging member; a shaft support adjustablely connected to the bridging member, wherein the shaft support is movable perpendicular to the bottom of the interior of the mold; a shaft connected to the shaft support and having a distal end, wherein the shaft is aligned with the central axis and rotatable about the central axis, and wherein the shaft, together with the shaft support, moves perpendicular to the bottom of the interior of the mold; at least one blade connected to the distal end of the shaft and perpendicular to the central axis of the mold, and rotatable together with the shaft about the central axis of the mold; wherein the shaft support is configured to be adjusted to position the at least one blade in contact with the powder in the mold, and the shaft is configured to be rotated to rotate the at least one blade to spread the powder in the mold, wherein the bridging member is removably mounted on the mold and spans the interior of the mold.

[0009] The device also preferably includes the bridging member having a crossover portion and a foot that supports the crossover portion at a spaced distance above the interior of the mold; and more preferably, the spaced distance above the interior of the mold is at least 2.0 inches (5.08 cm) above the mold. Also preferably, the at least one blade of the device includes two blades extending opposite each other from the distal end of the shaft. Preferably, the shaft support of the device further includes at least one track extending from the bridging member toward the interior of the mold, wherein the shaft support is slidably mounted on the at least one track.

[0010] Similarly, the device preferably includes a threaded rod extending through the shaft support, which is rotated within the shaft support to adjust the height of the shaft support. More preferably, the at least one blade of the device forms an acute angle with the surface of the powder during rotation of the shaft, and wherein the acute angle is adjustable.

[0011] Preferably, the bridging element of the device includes an anodized surface that inhibits the powder from adhering to the surface. Depending on the application, the device may also be made of plastic, stainless steel, or coated steel.

[0012] More preferably, the bridging member includes opposing ends, each end including an alignment pin that can be received in a diametrically opposed alignment recess in the mold when the bridging member is mounted on the mold. Preferably, this feature helps to prevent the spreading device from contacting the wall of the mold housing itself.

[0013] Most preferably, the mold used with the device is a sintering mold designed to be heated together with the powder inside by applying pressure.

[0014] In one aspect, this disclosure describes a method for spreading powder inside a cylindrical mold, wherein the interior includes a bottom, a central axis, and an internal diameter. The method includes: placing powder inside the mold; mounting a bridging member across the interior of the mold over the powder; lowering at least one blade from the bridging member until the blade contacts the powder; and rotating the blade about the central axis to spread the powder. Preferably, the bridging member mounted across the interior of the mold is removably mounted on the mold.

[0015] The method preferably further includes the following additional steps: after rotating the at least one blade, removing the bridging member and the at least one blade from the mold; placing another type of powder on top of the powder previously placed in the mold; mounting another bridging member across the interior of the mold on top of the other powder; lowering another at least one blade from the other bridging member until the other at least one blade contacts the different type of powder; and rotating the other at least one blade to spread the different type of powder in the mold. More preferably, the bridging member includes a surface, and the method further includes treating the surface to inhibit powder adhesion to the surface.

[0016] The method also preferably includes the additional step of providing the blade with an angle relative to the powder.

[0017] The method also preferably includes an additional step of placing more powder into the mold after other steps have been performed, and repeating the operation of lowering at least one blade and rotating at least one blade after more powder has been placed into the mold.

[0018] More preferably, the mold of the method includes a pair of alignment recesses positioned relative to each other across the interior of the mold, the method further includes providing alignment pins corresponding to the alignment recesses protruding from the bridging member, and the mounting bridging member includes inserting each alignment pin protruding from the bridging member into a corresponding alignment recess of the mold. Most preferably, the mold in the method is a sintering mold.

[0019] It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, intended to provide further explanation of the claimed invention. Attached Figure Description

[0020] This disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, the various features in the drawings are not to scale. Rather, for clarity, the dimensions of the various features have been arbitrarily enlarged or reduced. The drawings include the following figures:

[0021] Figure 1 A perspective view illustrating an embodiment of an apparatus for spreading powder in a mold is shown;

[0022] Figure 2 Examples Figure 1 A cross-sectional view of the device;

[0023] Figure 3 Examples Figure 1 A perspective view of a portion of the device; and

[0024] Figure 4 An implementation plan for the process / method is illustrated. Detailed Implementation

[0025] Figure 1 A perspective view illustrating an embodiment of an apparatus 10 for dispensing powder in a mold 12 is shown. The mold includes an interior (also referred to as a cavity) 47, which is cylindrical and includes a bottom, a diameter greater than or equal to at least twelve inches (30.48 cm), and a central axis perpendicular to the bottom. The apparatus 10 includes a bridging member 14 removably mounted on the mold 12. Specifically, the bridging member 14 includes a pair of legs 16 that contact the upper edge 18 of the mold 12 and centrally support the bridging member across the interior of the mold 12. More specifically, the bridging member 14 includes alignment pins 20 projecting from each leg 16 of the bridging member 14 (see [link to relevant documentation]). Figure 2 The alignment pin aligns with the bridge member 14, such that the bridge member is centered above the interior of the mold 12 and extends along the diameter of the mold.

[0026] Go to Figure 2A cross-sectional view illustrating an embodiment of the device 10 and mold 12 is shown, in which each alignment pin 20 is visible. Each alignment pin 20 is received in an alignment recess 22 formed in the upper edge of the mold 12. In this embodiment, the alignment recess 22 is also used when the mold is placed into a sintering chamber (not shown) to ensure that the mold is properly positioned and oriented within the sintering chamber. By placing the device 10 on the upper edge of the mold 12 such that each alignment pin 20 slides into the alignment recess 22 of the mold 12, the bridging member 14 is removably mounted on the mold 12, ensuring the correct positioning of the device 10 on the mold 12. In this preferred embodiment, the mold 12 includes diametrically opposed alignment recesses 22, and the bridging member 14 includes opposing ends, each end including an alignment pin 20, which is received in one of the alignment recesses when the bridging member 14 is mounted on the mold 12.

[0027] Continue to refer to Figure 2 The device 10 of this embodiment includes a shaft support 24 connected to the bridging member 14, wherein the shaft support 24 is adjustable upward and downward relative to the interior of the mold 12. Specifically, the shaft support 24 can be adjusted to move closer to the interior of the mold 12, or adjusted to move further away from the bottom 49 of the mold interior 47. More specifically, the shaft support 24 is mounted on a track 26 that guides the shaft support 24 toward and away from the bottom 49 of the mold interior 47. Figure 3 A perspective view of a portion of the device 10 is shown, in which each of the tracks 26 is visible. In this embodiment, there are three tracks 26 to which the shaft support 24 is movably mounted.

[0028] exist Figure 3 In the illustrated embodiment, device 10 includes a threaded rod 28 rotatably supported by bridging member 14 and extending through shaft support member 24. In this embodiment, threaded rod 28 engages with an internal thread formed in shaft support member 24. To adjust shaft support member 24, threaded rod 28 is rotated by turning knob 30 at the upper end of rod 28. When rod 28 is rotated, external thread of rod engages with internal thread in shaft support member 24, driving shaft support member 24 up or down along track 26 depending on the direction of rotation of rod 28. In this preferred embodiment, device 10 includes track 26 extending from bridging member 14 toward the interior of mold 12, wherein shaft support member 24 is slidably mounted on track. Preferably, the device includes multiple tracks 26 on which shaft support member 24 is slidably mounted, as shown in the illustrated configuration. Preferably, the travel per revolution of the knob 30 is less than 0.125 inches (0.318 cm), more preferably less than 0.1 inches (0.254 cm), and most preferably less than 0.05 inches (0.127 cm).

[0029] In this embodiment, the device 10 includes a shaft 32 rotatably mounted to a shaft support 24. When the height of the shaft support 24 is adjusted via a knob 30 and a threaded rod 28, the shaft 32 moves upward and downward together with the shaft support 24. The end of the shaft 32 closest to the interior of the mold (the distal end) supports one or more blades 34. Preferably, at least two blades 34 are present, with a first blade extending vertically from the distal end of the shaft 32 in one direction and a second blade extending from the distal end of the shaft in the opposite direction to the first blade. In this preferred embodiment, a hub 37 is connected to the distal end of the shaft 32, and the first and second blades are mountable to opposite sides of the hub 37. Each blade 34 rotates together with the hub 37 and the shaft 32. To rotate the shaft 32, the device 10 includes a handle 38 mounted to the proximal end of the shaft 32. An operator can use the handle 38 to rotate the shaft 32 about its longitudinal axis. When the shaft 32 is rotated, the hub 37 and the blades 34 rotate together with the shaft 32. To facilitate the operator's rotation of the handle 38, the handle 38 includes an upwardly protruding knob 39.

[0030] In this preferred embodiment, the height of the shaft support 24 is adjusted to position at least one blade 34 in contact with the powder in the mold, and the shaft 32 is rotated to rotate the blade 34 and spread the powder in the mold 12. In this preferred embodiment, a punch (not shown) is inserted into the bottom of the mold 12, which closes the bottom of the mold 12 and retains the powder inside the mold.

[0031] refer to Figure 2 The bridging member 14 includes a bridging portion 36 and legs 51 that support the bridging portion 36 at a distance 42 spaced above the interior 47 of the mold 12. Each leg 51 slopes downward from the bridging portion 36 and supports the bridging member at a distance 42 above the mold 12. The distance 42 provides an open area between the bridging member bridging portion 36 and the interior 47 of the mold to facilitate the addition of powder to the interior of the mold when the device 10 is installed into the mold 12. The legs 16 also contribute to supporting the bridging portion 36 at a distance 52 above the interior of the mold 12. In particular, the distance 42 provides space for the operator to pour additional powder into the mold 12, which may be necessary to fill low areas or add additional powder layers of different materials. Preferably, the distance is equal to or greater than 2.0 inches (5.09 cm), more preferably greater than or equal to 4 inches (10.16 cm), and most preferably greater than or equal to 6.0 inches (15.24 cm). However, the distance should be less than 18 inches (45.72m), and more preferably 12 inches (30.48cm) or less.

[0032] In this preferred embodiment, each blade 34 is preferably made of smooth, polished stainless steel to inhibit powder adhesion to its surface. Furthermore, each blade 34 has an adjustable angle to facilitate powder application when the blade 34 is rotated within the mold 12. When rotating the blade 34 to apply powder, the angle is preferably an acute angle of rotation towards the powder, which, when the blade is rotated, tends to fill low points (valleys) and flatten high points (peaks). An obtuse angle of rotation towards the powder is preferred, as this tends to cause the blade to penetrate the powder surface and leave gaps / valleys in the powder. Preferably, the acute angle should be between 10 and 80 degrees, more preferably between 20 and 60 degrees, and most preferably between 25 and 45 degrees. The distal end of each blade 34 should be spaced 0.060 inches (0.1524 cm) to 0.25 inches (0.6096 cm) from the inner surface of the mold and any lining therein. This provides clearance for the distal end of the blade to prevent impact with the mold or its lining. Such impacts are undesirable because they remove material from the mold surface and / or lining, and contaminate the powder or damage the mold and lining.

[0033] The bridging member 14, including the bridging portion 36, the support leg 16, and the leg 51, is preferably made of anodized aluminum. Anodized surfaces tend to inhibit powder adhesion, and aluminum is a lightweight and relatively inexpensive metal. To further reduce weight, the bridging portion 36 includes opposing sides 44 and 46 fastened together by a spacer 48 (see [link to bridging member]). Figure 1 The spacer 48 is preferably formed of anodized aluminum or other materials that provide sufficient rigidity, such as titanium, steel, or plastic. However, to reduce weight, a lighter material is preferred, making it easier for the operator to place and remove the spreader 10.

[0034] Figure 4An implementation of the process is illustrated. Initial process step 50 is to provide a mold 12 with a punch (not shown), which is inserted into the bottom of the mold 12 to form a container for receiving the powder to be sintered. The next step 52 is to place the powder in the mold 12, i.e., to pour the powder into the interior 47 of the mold 12. This is followed by step 54, which involves installing a bridging member 14 over the powder across the interior of the mold 12. After the bridging member 14 has been installed on the mold 12, the next step 56 is to lower at least one blade 34 from the bridging member 14 until the blade contacts the powder. The aforementioned step 56 of lowering at least one blade 34 assumes that at least one blade 34 is already at a height above the powder. Generally, when the bridging member 24 is installed on the mold 12, it is not desirable for at least one blade 34 to contact the powder, as this would cause the blade to penetrate the powder and create gaps / valleys that must be smoothed out. After the bridging member has been installed on the mold in step 54 and after one or more blades 34 have been lowered to contact the powder in step 56, the next step 58 is to rotate one or more blades to spread the powder. In this embodiment, the blade 34 should be tilted to form an acute angle relative to the powder surface, wherein the acute angle is rotated toward the powder. After the blade is rotated in step 58 until the powder is evenly distributed, the next step 60 is to remove the device 10 so that the mold 12 is ready to be placed in the sintering chamber or to add another layer of powder.

[0035] Therefore, after removing device 10, decision box 62 is executed to determine whether another layer should be placed. If the decision is negative, the process ends in box 64, and the mold can then be prepared for placement in the sintering chamber. If the decision is positive, another powder type corresponding to the composition of that layer is placed in mold 12 in process box 66.

[0036] Subsequently, in process box 68, another bridging member 14 is mounted on mold 12, then in box 70, blade 34 is lowered to contact the powder, and then in box 72, at least one blade 34 is rotated to spread the powder. The process then returns to decision box 62 to determine whether to place another layer. If the decision is negative, the process ends. This process is repeated until no more layers need to be placed.

[0037] The aforementioned process uses different devices 10 to place different powder types. This prevents the powder layer from being contaminated by residual powder particles that may adhere to at least one blade 34 or other part of the device 10. If contamination is not a concern, in an alternative embodiment, the same device 10 can be used to place another powder layer, thereby reducing the number of process steps.

[0038] Modifications and variations can be made based on the foregoing teachings, or modifications and variations can be obtained from the practice of the invention. For example, three or more blades 34 may be provided. The number of tracks 26 may be reduced or increased. A rack and pinion assembly may be used instead of the threaded rod 28 to adjust the height of the shaft support 24. The embodiments described above were chosen to explain the principles of the invention and its practical application, so that those skilled in the art can utilize the invention in various embodiments and with various modifications suitable for the particular intended use. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. An apparatus for spreading powder in a cylindrical mold, the cylindrical mold having an interior, the interior having a bottom, a central axis, and an interior diameter, the apparatus comprising: a bridge; a shaft support adjustably coupled to the bridge, wherein the shaft support is movable perpendicular to the bottom of the interior of the mold; a shaft coupled to the shaft support and having a distal end, wherein the shaft is aligned with the central axis and is rotatable about the central axis, and wherein the shaft moves with the shaft support (24) perpendicular to the bottom of the interior of the mold; at least one blade coupled to the distal end of the shaft and perpendicular to the central axis of the mold, and rotatable with the shaft about the central axis of the mold; wherein the shaft support is configured to be adjusted to place the at least one blade in contact with the powder in the mold, and the shaft is configured to be rotated to rotate the at least one blade (34) to spread the powder in the mold, characterized in that the bridge is removably mountable on the mold and spans the interior of the mold.

2. The apparatus of claim 1, wherein the bridge includes a span and a foot that supports the span a distance spaced above the interior of the mold.

3. The apparatus of claim 2, wherein the distance spaced above the interior of the mold is at least 2.0 inches (5.08 cm) above the mold.

4. The apparatus of claim 1 or 2, wherein the at least one blade includes two blades extending oppositely from the distal end of the shaft.

5. The apparatus of claim 1 or 2, wherein the shaft support includes at least one rail extending from the bridge toward the interior of the mold, wherein the shaft support is slidably mounted on the at least one rail.

6. The apparatus of claim 5, further comprising a threaded rod extending through the shaft support, the threaded rod being rotated in the shaft support to adjust the height of the shaft support.

7. The apparatus of claim 1 or 2, wherein the at least one blade forms an acute angle with a surface of the powder during rotation of the shaft, and wherein the acute angle is adjustable.

8. The apparatus of claim 1 or 2, wherein the bridge includes an anodized surface that inhibits the powder from adhering to the surface.

9. The apparatus of claim 1, wherein the bridge includes opposing ends, wherein each end includes an alignment pin that is receivable in diametrically opposed alignment recesses of the mold when the bridge is mounted on the mold.

10. The apparatus of claim 1, wherein the mold is a sintering mold.

11. A method of spreading powder within an interior of a cylindrical mold, wherein the interior includes a bottom, a central axis, and an interior diameter, the method comprising the steps of: placing powder in the interior of the mold; installing a bridge across the interior of the mold over the powder; lowering at least one blade (34) from the bridge until the at least one blade contacts the powder; and rotating the at least one blade about the central axis to spread the powder, characterized in that the bridge is removably installable on the mold.

12. The method of claim 11, further comprising the steps of: after the rotating the at least one blade, removing the bridge and the at least one blade from the mold; placing another, different type of powder in the mold over the powder previously placed in the mold; installing another bridge across the interior of the mold over the other powder; lowering another at least one blade from the other bridge until the other at least one blade contacts the different type of powder; and rotating the other at least one blade to spread the different type of powder in the mold.

13. The method of claim 11, wherein the bridge includes a surface, the method further comprising treating the surface to inhibit powder from adhering to the surface.

14. The method of claim 11, further comprising providing a pitch of the at least one blade relative to the powder.

15. The method of claim 11, further comprising placing more powder in the mold after the other steps have been performed, and repeating the lowering the at least one blade and the rotating the at least one blade after the more powder has been placed in the mold.

16. The method of claim 11, wherein the mold includes a pair of alignment recesses positioned across the interior of the mold from one another in the mold, the method further comprising providing alignment pins protruding from the bridge corresponding to the alignment recesses, and the installing a bridge includes inserting each alignment pin protruding from the bridge into a corresponding alignment recess of the mold.

17. The method of claim 11, wherein the mold is a sintering mold. ​ ​

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