TWI880722B - Automated pyrometer tracking - Google Patents

Abstract

Components, systems, assemblies, and methods related thereto for automatic alignment of a temperature measurement device with a die cavity in a sintering process are described. These include monitoring temperature of a location on a die, and include a pyrometer, laser measuring devices mounted to the pyrometer, and projecting a laser beam and measuring distance from the laser measuring device to a location on which the laser beam is projected. Each laser device outputs a signal and an actuator adjusts the pyrometer position in accordance with these signals.

Description

Automated Pyrometer Tracking

The present invention relates to methods and systems for spark plasma sintering (also known as DC sintering) in which a temperature measurement device is used to monitor the temperature of specific locations on a mold that undergoes motion, such as vertical, horizontal, or a combination thereof, during processing.

Spark plasma sintering (SPS) (also known as direct current sintering (DCS) and field assisted sintering technique (FAST)) is a pressure-assisted sintering technique capable of processing both conductive and non-conductive materials. SPS/DCS provides faster densification and material property enhancement, the mechanisms of which are still under investigation. However, the most commonly accepted mechanisms are faster heating rates, Joule heating, and possibly the effect of the electric field on densification.

During a typical SPS/DCS process, an ON-OFF current (usually a square wave DC pulse or a continuous DC current) is applied to a powder (generally composed of graphite, but not excluding metals, ceramics, or composites) contained in a punch and die type tool set to generate Joule heat and contain pressure. Graphite is the most common material because it is a good conductor of electricity and is stable to extremely high temperatures. The abbreviation DCS is sometimes used to indicate a system that provides non-pulsed DC power to the die. However, SPS and DCS are often used to mean the same type of equipment and are used interchangeably herein. In an SPS/DCS equipment, the heat is transferred to the powder by thermal conduction from the die, and if the powder is conductive, the current can flow through the powder to generate Joule heat directly in the material being sintered.

The operating or monitoring temperature range in SPS equipment is in the range of 200°C to 2400°C. Material processing (pressure and temperature ramp and hold time) in SPS equipment is generally completed in a shorter period of time than in previous technologies. Faster processing times provide greater control over grain growth and microstructure, which enhances material properties directly related to microstructure, such as strength, toughness, electrical properties, thermal properties, optical properties, and corrosion and erosion resistance.

Temperature during sintering is typically monitored using a thermocouple or pyrometer positioned within the confines of the mold. Thermocouples are less effective due to their sensitivity to stray voltages due to the presence of electric fields in the tool. In order to ensure optimal sintering conditions, it is important to identify a consistent control point and monitor the temperature at that location throughout the process. However, during the sintering process, compaction and densification of the powder occurs, resulting in the need to dynamically position the pyrometer as the sintered product is formed. More specifically, the reason the pyrometer must be moved is because the mold shell itself moves during compaction and densification. Repositioning of the pyrometer relative to the mold is typically done manually, which is often difficult to do consistently and in a timely manner because the optimal positioning changes over sintering time. Inaccuracies cause variability in product quality, especially from run to run.

Components and methods for automatic pyrometer tracking in sintering are known, such as those found in the following prior art patents, patent publications, and non-patent documents (if any) (which are found in the Appendix and are incorporated by reference in their entirety), which are disclosed solely for prior art purposes and in relation to the best current technology, but do not contain one or more of the elements of the present invention: for example, in U.S. Patent Publication No. 2016/0325353 and U.S. Patent No. 4,936,765, and can be found in the Appendix.

In fact, the basic block diagram of a typical SPS/DCS apparatus can be found in U.S. Patent Publication No. 2016/0325353 (see Appendix), including the SPS/DCS system of the present invention. As shown in FIG. 1 of U.S. Patent Publication No. 2016/0325353, the sintering apparatus 100 includes a vacuum chamber 102 located in a carrier 104 , and further includes an observation window 106 and a temperature measurement device 108 , both of which are incorporated into the vacuum chamber 102. The material to be sintered (generally a powder material) is loaded into a mold set 111 and placed in the vacuum chamber 102 of the sintering apparatus 100 , where a process is performed. More specifically, as shown, the mold assembly 111 includes a housing 112 and two opposing plungers (a lower plunger 120 and an upper plunger 122 ) forming a mold cavity 110 in which the material to be sintered is placed. The sintering apparatus 100 further includes a hydraulic power unit 116 and a hydraulic cylinder 118. The hydraulic power unit provides power to the hydraulic cylinder, which in turn is used to move the lower plunger and the upper plunger up and down to manipulate the applied mechanical force (or pressure) to compress the sinterable material during the process. The force can be measured and monitored, for example, using a load cell. Additionally, a DC power supply 114 provides the necessary current within the vacuum chamber 102 during compression. As shown, the sintering apparatus 100 also includes a vacuum pump 124 that allows the apparatus to operate under negative atmospheric pressure. If desired during the process, a gas 126 can also be injected into the vacuum chamber 102. A central control system 128 can be used to control various aspects of the sintering apparatus during use. For example, the control system can be used to control the DC power supply, the hydraulic power unit, the vacuum pump, and control the amount of any inert gas introduced into the vacuum chamber during use.

Additionally, as shown in FIG. 2 of U.S. Patent Publication No. 2016/0325353 (see Appendix), a mold assembly 211 includes a housing 212 and two opposing plungers (lower plunger 220 and upper plunger 222 ) forming a mold cavity in which the material 205 (powder) to be sintered is placed. As shown, the mold cavity is vertically symmetrical, although other shapes are possible. The target position of the mold cavity is identified, which in this example is the geometric centerline of the material. Assuming that the density is constant throughout the sample (especially vertically) and heating is applied, this will be the location relative to the highest measurable temperature of the powder. As can be seen in FIG. 2 of U.S. Patent Publication No. 2016/0325353 (see Appendix), when the powder is sintered to form the desired sintered portion 295 , the positioning of the centerline changes.

The prior art does not disclose a method or system that provides unmanned tracking of pyrometer holes or recesses in a mold for a field assisted sintering apparatus with sufficient accuracy.

Therefore, while spark plasma methods and systems are known, there is a need to provide both a sintering system and method for improving process consistency both during and between cycles.

To meet these and other needs, and with these objectives in mind, the present disclosure relates to assemblies and related methods for aligning a temperature measurement device with a mold cavity during a sintering process.

In one aspect, the present disclosure describes a system for monitoring the temperature of a location on a mold. The system includes a pyrometer having one end, the pyrometer being configured to measure the temperature based on the intensity of thermal radiation received at the end of the pyrometer, and the pyrometer having opposing sides.

The system also includes a first laser measurement device and a second laser measurement device, which are mounted to the pyrometer, one of the laser measurement devices is mounted near one side of the pyrometer, and the other laser measurement device is mounted near the opposite side of the pyrometer, each laser measurement device projects a laser beam and measures the distance from the laser measurement device to a location on which the laser beam is projected, and each laser measurement device outputs a signal indicating that the measured distance is less than or equal to a minimum distance. The system includes an actuator that is communicatively connected to each laser measuring device and receives the signal output from each laser measuring device. The actuator supports the pyrometer and moves the pyrometer in a first direction and a second direction relative to each other according to the signals received from the laser measuring devices until the received signals indicate that the measured distance is not less than or equal to the minimum distance.

When the received signals indicate that the measured distance is greater than the minimum distance, the end of the pyrometer is positioned relative to the location on the mold to receive thermal radiation therefrom and output a temperature signal based on the intensity of the thermal radiation.

The pyrometer includes a top and a bottom, wherein one of the laser measurement devices is mounted near the top of the pyrometer and the other laser measurement device is mounted near the bottom of the mold, and the actuator moves the pyrometer up and down. When the actuator receives a signal from one of the laser measurement devices, the actuator moves the pyrometer downward, and when the actuator receives a signal from the other laser measurement device, the actuator moves the pyrometer upward. However, if the system receives a signal from both of the laser measurement devices, the actuator does not adjust the positioning of the pyrometer.

The mold includes a height, and the actuator moves the pyrometer parallel to the height of the mold. In another aspect, the laser measurement device is vertically aligned along the height of the mold. In a further aspect, each laser measurement device is mounted at an equal distance from the mold, wherein the distance is measured from a point on the outer wall of the mold closest to the laser measurement device. Further, the actuator is programmable.

In another aspect, the present disclosure describes a method for tracking a recess in a mold using a temperature measurement device. The method includes: mounting a first laser and a second laser to a temperature measurement device in opposition to each other to create a pyrometer assembly; aligning the temperature measurement device with the recess using the first laser to project a laser beam into the recess to measure a first laser beam distance and projecting the second laser beam into the recess to measure a second laser beam distance; and when a decrease in the first laser beam distance or the second laser beam distance is detected, realigning the temperature measurement device with the recess by moving the pyrometer assembly so that the first laser beam and the second laser beam are projected into the recess.

The mold includes a height, and the mounting step includes mounting the first laser and the second laser relatively along the height of the mold. When a decrease in the distance of the first laser beam is detected, the pyrometer assembly moves in a first direction, and when a decrease in the distance of the second laser beam is detected, the pyrometer assembly moves in a second direction opposite to the first direction.

Each laser is integrated with a laser measurement device that detects when there is a decrease in laser beam distance and provides a signal. The method further includes the steps of mounting the pyrometer assembly to an actuator and receiving the signals using the actuator, and performing a realignment step by moving the pyrometer assembly using the actuator in accordance with the received signals.

The method further includes the steps of mounting the pyrometer assembly to an actuator and using the actuator to perform the aligning step and the realigning step. The mounting step includes mounting the lasers equidistant from a point on the mold that is closest to each laser.

In yet another aspect, the present disclosure describes a method for forming a sintered product, which includes the following steps in any order: i) loading a material to be sintered into a mold cavity of a mold set, the mold set including a shell and opposing plungers configured to compress the material; ii) placing the mold set into a vacuum chamber of a sintering apparatus, the sintering apparatus including: a temperature measuring device configured to determine the temperature of the material in the mold cavity during sintering; and a control system configured to move the temperature measuring device during sintering; iii) using a first laser and a second laser of a temperature measuring device to position the temperature measuring device relative to a target position of the mold cavity to establish a pyrometer assembly; using The first laser projects a laser beam into the mold cavity to establish a first laser beam distance, and uses the second laser beam to project into the mold cavity to establish a second laser beam distance to align the temperature measurement device with the mold cavity; when a decrease in the first laser beam distance or the second laser beam distance is detected, the temperature measurement device is automatically realigned with the mold cavity by moving the pyrometer assembly so that the first laser beam and the second laser beam are projected into the mold cavity, and iv) compressionally sintering the material in the mold cavity to form the sintered product, wherein during the compression sintering, the temperature measurement device is moved using the control system to maintain relative positioning with the target position of the mold cavity.

In a more detailed aspect of the aforementioned method, the sintering apparatus further comprises a repositioning device in communication with the temperature measuring device and the control system, and wherein the temperature measuring device is moved by the repositioning device using the control system. In still more details of the method, the mold assembly comprises a housing, an upper plunger, and a lower plunger, and the step of moving the temperature measuring device comprises determining a position of the upper plunger, the lower plunger, or both. In still further details, the temperature measuring device moves continuously during the compression sintering. In more detail, moving the temperature measuring device is automatic, and the sintering apparatus is a spark plasma sintering apparatus or a DC sintering apparatus.

In another aspect, the present disclosure describes an automatic pyrometer tracking control system, comprising: a mold having a mold cavity, the mold having a temperature measurement device opening, the temperature measurement device opening having a first edge portion and a second edge portion having a target depth; a first laser having a first laser beam; a second laser having a second laser beam; a temperature measurement device for observing a temperature of the mold through the temperature measurement device opening; and at least one sensor for measuring a first laser beam distance to the target depth and a second laser beam distance to the target depth; and wherein the first laser and the second laser are mounted on the temperature measurement device. A pyrometer assembly is established on opposite sides of the device; and wherein the first laser beam is located near the first edge portion, and the second laser beam is located near the second edge portion, so that the first laser beam and the second laser beam contact the target depth, establishing the first laser beam distance and the second laser beam distance; and wherein the at least one sensor detects the first laser beam distance and the second laser beam distance, and wherein if the at least one sensor detects a decrease in the first laser beam distance or the second laser beam distance, the sensor provides a signal to realign the pyrometer assembly, so that the at least one sensor detects a first laser beam distance to the target, and a second laser beam distance to the target.

Through the detailed description of the preferred embodiments herein and the illustrations of the related drawings, the structure, overall operation, and technical features of the present invention will become apparent.

It should be understood that both the foregoing general description and the following embodiment are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

The present invention relates to methods and systems/apparatus for sintering materials under compression.

Generally, compression sintering processes, such as hot pressing and spark plasma sintering (SPS) (SPS is also known as direct current sintering (DCS)) involve the use of pressure and high temperature to convert the material to be sintered, especially in the form of particles or powder (fine particles), into a higher density product. SPS is a pressure-assisted direct current heating sintering process that uses uniaxial force and direct current to consolidate powdered materials. Specifically, DC voltage and current are applied to a conductive mold assembly (mold set). Compared to conventional hot pressing, where heat must be transferred from the outside into the mold set by radiation heating elements, high heating rates can be achieved because the heat is generated within the mold set and potentially within the powder. During SPS sintering, heat is generated in and around the material in the mold, rapidly heating the material and limiting particle/grain growth due to the speed of the process. The entire process from powder to finished sintered sample is completed faster with high uniformity.

In the SPS process, it is believed that the current flowing between the particles can assist in the removal of fine impurities and gases on and between the particle surfaces due to dielectric collapse and localized heating of the surface oxide. Additionally, the higher heating rates that can be achieved allow fine powders to be heated to high temperatures before grain coarsening can occur, allowing the powder to retain a high surface area to aid in the sintering process, which proceeds more rapidly.

Force (pressure) also plays an important and predictable role in limiting particle growth and affecting the overall density of the SPS system. For example, when the material moves under pressure, especially during the early sintering stages, the force multiplies the diffusion of the entire sample. Both too much and too little pressure can negatively affect the process. In large samples where high density is required, the force is often increased in stages to enhance outgassing at low temperatures and sintering diffusion at high temperatures. Accordingly, accurate manipulation of force can enhance the process.

For compression sintering systems, temperatures need to be accurately determined in order to monitor and control the process to consistently produce sintered products with desired and predictable properties. As the material is consolidated and compressed, the temperature distribution across the product changes. For example, the highest temperature changes across the location of the material, and as a result, the temperature measuring device (such as a pyrometer) must be repositioned during the sintering process to track and maintain monitoring of this location to provide accurate process control. This is generally done manually, which is time consuming to do accurately, especially for sintering projects that take several hours. Therefore, in the method and apparatus of the present invention, a control system is used to assess the relative positioning of a temperature measuring device to a target position of a mold cavity of a mold assembly, wherein the control system causes a repositioning of the temperature measuring device to maintain a constant relative positioning.

Specific examples are shown in Figures 3 and 4. However, it should be apparent to those skilled in the art that this is merely illustrative and non-restrictive in nature and is presented by way of example only. Many modifications and other embodiments are within the skill of those skilled in the art and are contemplated to fall within the scope of the present invention. Additionally, those skilled in the art will appreciate that the specific conditions and configurations are exemplary and that actual conditions and configurations will depend on the particular system. Using no more than routine experimentation, those skilled in the art will also be able to recognize and identify equivalents to the specific elements shown.

In this example, the pyrometer is placed at a position relative to the mold assembly to monitor the temperature of a target location of the mold cavity, which is a recess in the mold outer wall near the centerline of the mold cavity. When compression sintering has begun, the position of the recess relative to the pyrometer is monitored and adjusted.

For example, a motorized stage can be used to reposition the pyrometer. This repositioning method can be repeated as often as desired throughout the compression sintering process, either stepwise (semi-continuously) or continuously. This automated process eliminates human error that occurs when manually adjusting the pyrometer positioning and improves process consistency by maintaining the same pyrometer positioning during each process cycle. Additionally, the method and system include a control system configured to move the temperature measurement device during sintering based on a real-time measurement system.

As shown in FIG3 , one embodiment of the present invention is directed to a system for monitoring the temperature of a location 10 on a mold 12. FIG3 shows a portion of a side view of the mold 12 in exaggerated form to facilitate description thereof. The mold 12 is located in a chamber of an SPS machine for sintering the material (not shown) contained in the mold 12. The SPS machine is of a known type and is commercially available from suppliers such as Thermal Technology LLC of Minden, Nevada, USA.

The mold 12 is surrounded by the walls of the chamber, one of which 14 is shown in FIG3 . The chamber walls, such as wall 14 , enclose and insulate the interior of the chamber from the external environment. Generally, the chamber is evacuated during sintering because the material constituting the mold will ignite and burn in the presence of oxygen at the temperatures generally reached during the sintering process.

During the sintering process, the temperature is monitored to ensure that the proper temperature is reached and maintained to sinter the material in the mold. FIG3 shows a pyrometer 16 positioned to monitor the temperature of the mold 12 at the aforementioned location 10. The pyrometer 16 is of known design and is commercially available from suppliers such as Fluke Process Instruments of Everett, WA, USA.

The pyrometer 16 is a type of remote thermometer that measures temperature based on the intensity of thermal radiation received at one end 18 of the pyrometer 16. In order to enable the pyrometer 16 to receive the thermal radiation radiated from the mold 12, the chamber wall 14 includes a window 20 (see FIG. 4 ) made of a material that is substantially transparent to the thermal radiation and can withstand high temperatures, such as quartz.

Referring to FIG. 4 , the window 20 is elongated, having a height that is substantially greater than its width. The long height of the window 20 allows the positioning of the pyrometer 16 to be adjusted to be opposite to the position 10 of the mold 12. Specifically, the position 10 is located at the bottom of a recess 22 formed in the side of the mold 12. Being located at the bottom or end of the recess 22, the position 10 is closer to the material being sintered than other positions along the side of the recess 10. Further, the recess 22 tends to direct thermal radiation outwardly along the central axis 23 of the recess 22. Therefore, adjusting the end 18 of the pyrometer to be opposite to the position 10 at the end of the recess 22 is the best positioning for most reliably and accurately measuring the temperature of the mold 12, that is, generally facing the position 10 at the end of the recess 22 in the mold 12 along the central axis of the recess.

A system for monitoring the temperature at a location 10 at the end of a recess 22 includes a first and a second laser measuring device 24 mounted to a pyrometer 16. One of the laser measuring devices 24 is mounted near one side of the pyrometer 16, and the other laser measuring device is mounted near the opposite side of the pyrometer. In operation, each laser measuring device 24 projects a laser beam 26 and measures the distance from the laser measuring device to the location onto which the laser beam is projected. For clarity of description, FIG. 3 shows only the upper laser measuring device 24 that projects the laser beam 26. However, in operation, each laser measuring device 24 projects a laser beam. The laser measuring devices 24 are of known design and are commercially available from suppliers such as Keyence Corporation of America in Itasca, IL, USA.

Each laser measurement device 24 projects a laser beam 26 and measures the distance from the laser measurement device to the location onto which the laser beam is projected. FIG. 3 shows the laser 26 projected onto a location 10 at the end of a recess 22 in the side of the mold 12. However, as will be appreciated, if the pyrometer 16 were positioned slightly higher up along the chamber wall 14, the laser beam 26 would hit the outside wall of the mold 12 and would not be projected into the recess 22. The distance from each laser measurement device 24 to the outside wall of the mold 12 is defined herein as a minimum distance 28 (see FIG. 5 ) and should be the same or close to the same value for each laser measurement device 24.

Each laser measuring device 24 outputs a signal indicating whether the measured distance is less than or equal to a minimum distance 28; FIG. 5 schematically illustrates the minimum distance 28 in a simplified geometry of the monitoring system 12 and when the chamber wall 14 is omitted. In FIG. 5 , the pyrometer 16 is positioned higher relative to the recess 22 than the pyrometer positioning of FIG. 4 . Therefore, the distance measured by the upper laser measuring device is the same as (not greater than) the minimum distance 28, and the upper laser measuring device accordingly outputs a signal indicating that the measured distance is less than or equal to the minimum distance 28. In contrast, the lower measuring device 24 is positioned such that its laser beam is projected into the recess 22. Therefore, the lower measuring device 24 outputs a signal indicating that the measured distance is not less than or equal to the minimum distance. Instead, each laser measurement device is outputting a signal indicating whether its laser beam is projected into the recess 22. If the measured distance is less than or equal to the minimum distance, the laser beam is projected onto the side of the mold 12 instead of into the recess 22.

In this regard, the laser measurement device can be programmed so that the minimum distance 28 can be adjusted to correspond to the SPS equipment being used with the temperature monitoring system. For example, if the particular SPS equipment is larger and has thicker chamber walls 14, the minimum distance 28 can be programmed to a larger value. Additionally, the signal can be modified to output a signal indicating that the measured distance is greater than the minimum distance 28. Alternatively, the signal can output the measured distance rather than a binary signal.

Returning to FIG. 3 , the temperature monitoring system includes an actuator 32 that is communicatively coupled to each laser measurement device 24 and receives signals outputted from each laser measurement device. The actuator 32 supports the pyrometer 16 and moves the pyrometer in first and second directions relative to each other in response to signals received from the laser measurement devices until each received signal indicates that the measured distance is not less than or equal to a minimum distance. The actuator is of a known type that includes a stepper motor having an on-board programmable motion controller and drive electronics. Such actuators include those sold under the trademark MDRIVE, which are available from Schneider Electric of Andover, Massachusetts, USA.

Initially, the positioning of the pyrometer is manually adjusted by the operator to position the pyrometer relative to the recess 22. At this position, the laser beam 26 from each device 24 is projected into the recess 22 of the mold 12 and the temperature monitoring system is initiated. As the material in the device 12 sinters, the mold 12 moves up and down, as does the recess 22 because it is formed integrally with the mold. If any of the laser measurement devices 24 measures a distance less than or equal to the minimum distance 28, the laser measurement device outputs a signal to the actuator 23. The actuator 23 moves the pyrometer 16 in accordance with the received signal. If the received signal is from the upper laser measuring device 24, the actuator 23 moves the pyrometer downward until there is no longer a signal from the upper laser measuring device indicating that the measured distance is less than or equal to the minimum distance 28.

Conversely, if the actuator receives a signal from the second measuring device 24 (lower measuring device), the actuator 23 moves the pyrometer 16 upward until no signal is received. If the actuator 23 removes the signals from both laser measuring devices 24, this indicates an error condition requiring intervention from an operator to manually reposition the pyrometer 16. In the event of an error condition, the actuator 23 does not move the pyrometer 16 in either direction.

FIG6 is a flow chart of the logic of the temperature monitoring system. The system begins at block 32 after the operator has positioned the pyrometer 16 relative to the recess 22, wherein no signal is received from the laser measuring device 24 indicating that the measured distance is less than or equal to the minimum distance. The logic then proceeds to block 34, whereupon the actuator 23 monitors the receipt of a signal. If a signal is received, the logic determines in block 36 whether the signal indicating that the measured distance is less than the minimum distance 28 is received from only one of the laser measuring devices 24. If the determination is affirmative, the actuator 23 moves the pyrometer in accordance with the signal received in block 38. Specifically, if the signal comes from the upper laser measuring device 24, the upper laser measuring device 24 is too high and the actuator 23 moves the pyrometer 16 downward. If the signal comes from the lower measuring device 24, the lower laser measuring device 24 is too low and the actuator 23 moves the pyrometer 16 upward. When the laser measuring device is mounted to the pyrometer 16, the laser measuring device 24 moves with the pyrometer 16.

If the determination in block 36 is negative, the logic flow proceeds to block 40, where the actuator 23 does not take any action, that is, the pyrometer 16 does not move, and the logic then returns to the monitoring signal in block 34.

For ease of explanation, the terms upper and lower have been used in the foregoing description to distinguish the laser measurement devices 24 from each other. However, the terms first and second, or one and the other may also be used and are defined herein as being synonymous with upper and lower. In this regard, some sintering devices are not vertically configured and may have other orientations besides upper and lower.

When the laser measuring device 24 does not output a signal indicating that the measured distance is less than or equal to the minimum distance, the end of the pyrometer is positioned relative to the position 10 in the recess 22 of the mold 12 for receiving thermal radiation therefrom and outputting a temperature signal based on the intensity of the received thermal radiation.

The foregoing description of the preferred embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the present invention. The embodiments are chosen and described to explain the principles of the invention and its practical application so that one having ordinary knowledge in the art can utilize the invention in various embodiments and with various modifications suitable for the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

10: position 12: mold; monitoring system 14: wall 16: pyrometer 18: end 20: window 22: recess 23: center axis; actuator 24: laser measuring device; measuring device; device 26: laser beam; laser 28: minimum distance 32: block; actuator 34: block 36: block 38: block 40: block 100: sintering equipment 102: vacuum chamber 104: carrier 106: observation window 108: temperature measuring device 110: mold cavity 111: mold assembly 112: housing 114: DC power supply 116: Hydraulic power unit 118: Hydraulic cylinder 120: Lower plunger 122: Upper plunger 124: Vacuum pump 126: Gas 128: Central control system 205: Material 211: Mold set 212: Shell 220: Lower plunger 222: Upper plunger 295: Sintering part Appendix U.S. Patent Publication No. 2016/0325353, and U.S. Patent No. 4,936,765

The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to convention, the various features of the drawings are not drawn to scale. Instead, the sizes of the various features are arbitrarily expanded or reduced for clarity. The drawings include the following figures: [Figure 1] to [Figure 2] show the prior art of U.S. Patent Publication No. 2016/0325353. [Figure 3] shows a side view of an embodiment of the present invention. [Figure 4] shows a perspective view of a portion of the embodiment shown in Figure 3. [Figure 5] shows a simplified schematic diagram of the embodiment of Figure 3. [Figure 6] shows a logical flow chart of the embodiment of Figure 3.

10: Location

12: Mould

14: Wall

16: Thermometer

18: End

22: Concave part

23: Center axis; actuator

24: Laser measuring device; measuring device; device

26: Laser beam

Claims (20)

A system for monitoring the temperature of a location on a mold, the system comprising: a pyrometer having one end, the pyrometer configured to measure temperature based on the intensity of thermal radiation received at the end of the pyrometer, the pyrometer having opposing sides; A first laser measuring device and a second laser measuring device, which are mounted to the pyrometer, one of the laser measuring devices is mounted near one side of the pyrometer, and the other laser measuring device is mounted near the opposite side of the pyrometer, each laser measuring device projects a laser beam and measures the distance from the laser measuring device to a position on which the laser beam is projected, each laser measuring device outputs a signal indicating that the measured distance is less than or equal to a minimum distance, wherein the minimum distance is the distance from each laser measuring device to an outer wall of the mold; and An actuator is connected to each laser measuring device in communication and receives the signal output from each laser measuring device, the actuator supports the pyrometer, and moves the pyrometer in a first direction and a second direction relative to each other according to the signals received from the laser measuring devices, until each received signal indicates that the measured distance is not less than or equal to the minimum distance, wherein when each received signal indicates that the measured distance is greater than the minimum distance, the end of the pyrometer is positioned relative to the position on the mold to receive thermal radiation therefrom and output a temperature signal based on the intensity of the thermal radiation. A system as in claim 1, wherein the actuator moves the pyrometer up and down, and the pyrometer includes a top and a bottom, wherein one of the laser measuring devices is mounted near the top of the pyrometer and another laser measuring device is mounted near the bottom of the mold, and when the actuator receives a signal from one of the laser measuring devices, the actuator moves the pyrometer downward, and when the actuator receives a signal from the other laser measuring device, the actuator moves the pyrometer upward. A system as claimed in claim 1 or 2, wherein the actuator receives a signal from both of the laser measurement devices and the actuator does not adjust the positioning of the pyrometer. A system as in claim 1 or 2, wherein the mold includes a height and the actuator moves the pyrometer parallel to the height of the mold. A system as claimed in claim 1 or 2, wherein the laser measurement devices are aligned vertically along the height of the mold. A system as claimed in claim 1 or 2, wherein each laser measuring device is mounted at an equal distance from the mold, wherein the distance is measured from a point on the outer wall of the mold closest to the laser measuring device. A system as claimed in claim 1 or 2, wherein the actuator is programmable. A method for tracking a recess in a mold using a temperature measurement device, the method comprising the following steps: Mounting a first laser and a second laser to a temperature measurement device in opposition to each other to create a pyrometer assembly; Aligning the temperature measurement device with the recess by projecting a laser beam into the recess using the first laser to measure a first laser beam distance and projecting the second laser beam into the recess to measure a second laser beam distance; and When a decrease in the first laser beam distance or the second laser beam distance is detected, realigning the temperature measurement device with the recess by moving the pyrometer assembly so that the first laser beam and the second laser beam are projected into the recess. The method of claim 8, wherein the mold includes a height, and the mounting step includes mounting the first laser and the second laser relative to each other along the height of the mold. A method as claimed in claim 8 or 9, wherein when a decrease in the distance of the first laser beam is detected, the pyrometer assembly moves in a first direction, and when a decrease in the distance of the second laser beam is detected, the pyrometer assembly moves in a second direction opposite to the first direction. A method as in claim 8 or 9, wherein each laser is integrated with a laser measurement device that detects when there is a decrease in the laser beam distance and provides a signal. The method of claim 11 further comprises the steps of mounting the pyrometer assembly to an actuator and receiving the signals using the actuator, and performing a re-alignment step by moving the pyrometer assembly using the actuator according to the received signals. The method of claim 8 or 9, further comprising the steps of mounting the pyrometer assembly to an actuator and using the actuator to perform the alignment step and the realignment step. A method as claimed in claim 8 or 9, wherein the mounting step includes mounting the lasers equidistant from a point on the mold closest to each laser. A method for forming a sintered product, comprising the following steps in any order: i)      Loading a material to be sintered into a mold cavity of a mold set, the mold set comprising a shell and opposing plungers configured to compress the material; ii)     Placing the mold set in a vacuum chamber of a sintering apparatus, the sintering apparatus comprising a temperature measuring device and a control system, the temperature measuring device being configured to determine the temperature of the material in the mold cavity during sintering, and the control system being configured to move the temperature measuring device during sintering; iii)   Using a first laser and a second laser of a temperature measuring device to position the temperature measuring device relative to a target position of the mold cavity to establish a pyrometer assembly; using the first laser to project a laser beam into the mold cavity to establish a first laser beam distance, and using the second laser beam to project into the mold cavity to establish a second laser beam distance to align the temperature measuring device with the mold cavity; when a decrease in the first laser beam distance or the second laser beam distance is detected, automatically realigning the temperature measuring device with the mold cavity by moving the pyrometer assembly so that the first laser beam and the second laser beam are projected into the mold cavity, and iv)   The material in the mold cavity is compression-sintered to form the sintered product, wherein during the compression-sintering, the temperature measuring device is moved using the control system to maintain relative positioning with respect to the target position of the mold cavity. A method as claimed in claim 15, wherein the sintering apparatus further comprises a repositioning device in communication with the temperature measuring device and the control system, and wherein the temperature measuring device is moved via the repositioning device using the control system. A method as claimed in claim 15 or 16, wherein the mold assembly includes a housing, an upper plunger, and a lower plunger, and wherein the step of moving the temperature measuring device includes determining a position of the upper plunger, the lower plunger, or both. A method as claimed in claim 15 or 16, wherein the temperature measuring device moves continuously during the compression sintering period. A method as claimed in claim 15 or 16, wherein moving the temperature measuring device is automatic. A method as claimed in claim 15 or 16, wherein the sintering device is a spark plasma sintering device or a DC sintering device.