System and method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished

Abstract

The invention relates to a system for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished, wherein the system (100) comprises a sintering furnace (110) having a pressure regulating valve (112), wherein the pressure regulating valve (112) has an adjustable flow transmittance F, wherein the system (100) further comprises at least one information unit (122), wherein the information unit (122) is configured to generate an information signal (124) comprising information regarding the flow transmittance F as a function of time t, and wherein the system (100) further comprises an analysis unit (130), wherein the analysis unit (130) is configured to determine when the flow transmittance F has reached a steady state, and to determine that the process of removal of organic additives from a green body (102) is finished when the flow transmittance F has reached the steady state The invention also relates to a method (200) for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished.

Description

[0001] System and method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished

[0002] TECHNICAL FIELD

[0003] The present invention relates to a system and a method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished.

[0004] BACKGROUND

[0005] Cutting elements, such as cutting inserts, are conventionally manufactured by pressing a composite powder into a green body by means of uniaxial or multiaxial pressing, followed by sintering of the green body to obtain a sintered body. Alternatively, a green body may be formed by means of e.g. powder injection moulding (RIM), additive manufacturing, or extrusion.

[0006] The green body additionally comprises organic additives, such as polyethylene glycol (PEG), used as binding material, which are removed before the sintering process and / or during the sintering process by successively increasing the temperature to the sintering temperature. This process is commonly known as debinding or dewaxing. The removal of organic additives can be achieved e.g. in a catalytic process, by extraction in a suitable solvent, and / or by heating at a temperature lower than the sintering temperature. One common way of removing the organic additives is to supply hydrogen gas into the sintering furnace. The organic additives will then react with the hydrogen gas and create water and carbon dioxide. The process of removing organic additives from the green body is performed at atmospheric pressure, which is maintained by adjusting the flow transmittance of a pressure regulating valve at the sintering furnace. Such a conventional process for removing organic additives from the green body is described in e.g. EP 1510590 Bl.

[0007] A problem with the current systems and methods for removing organic additives from the green body is that it is very difficult to know when the process is finished. As a consequence, the process is performed for a longer time than necessary in order to make sure that the process is finished. This results in higher costs, both in time and material, than necessary.

[0008] SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to overcome, or at least partially overcome, said problem by introducing a system and a method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished.

[0010] The object of the present invention is achieved by means of a system for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished, wherein the system comprises a sintering furnace having a pressure regulating valve, wherein the pressure regulating valve has an adjustable flow transmittance F, wherein the pressure regulating valve is configured to regulate the pressure within the sintering furnace by adjusting the flow transmittance F, wherein the system further comprises at least one information unit operatively connected to the sintering furnace, wherein the information unit is configured to generate an information signal comprising information regarding the flow transmittance F as a function of time t, and wherein the system further comprises an analysis unit operatively connected to the at least one information unit, wherein the analysis unit is configured to perform the following steps:

[0011] -receiving the information signal from the at least one information unit;

[0012] -generating a filtered signal by applying a signal filter to the received information signal;

[0013] -determining a point in time tcontroi when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time to, wherein the time to is a point in time when the flow transmittance F constitutes a valley point on the filtered signal which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein Ti > 45 min, and wherein the time tcontroi is subsequent to the time to;

[0014] -activating a steady state function at the time tcontroi, wherein the steady state function is configured to determine a fluctuation D of the flow transmittance F over a second predetermined time period T2, wherein T2= O.ls-lOOs, preferably T2= ls-20s;

[0015] -determining if the flow transmittance F has reached a steady state by determining if the fluctuation D is equal to or less than a predetermined threshold fluctuation Dthreshoid, wherein Dthreshoid = 1-2%;

[0016] -activating the steady state function every n:th minute subsequent to the time tcontroi until the flow transmittance F has reached a steady state, wherein n = 3-7, preferably n = 4-6, more preferably n = 5; and

[0017] -determining that the process of removal of organic additives from the green body is finished when the flow transmittance F has reached the steady state.

[0018] Since the removal of the organic additives from the green body affects the pressure within the sintering furnace, which is in turn controlled by the pressure regulating valve, it is possible to determine when the process of removal of organic additives from the green body, also known as "the debinding process", is finished by analyzing the flow transmittance F of the pressure regulating valve. Thereby, it is possible to optimize the debinding process by not running it longer than necessary. Thereby, costs can be saved both in time and in material.

[0019] When the debinding process is finished, the flow transmittance F will reach a steady state. By determining when the flow transmittance F reaches a steady state, it is possible to determine when the debinding process is finished.

[0020] By applying a signal filter to the received information signal, noise present in the information signal is reduced. When the flow transmittance drops below the threshold transmittance Fthreshoid, the debinding progress is soon to be finished. By activating a steady state function at that time, the processing power required to determine when the debinding process is finished is reduced compared to if the steady state function would be continuously running.

[0021] By choosing the threshold transmittance Fthreshoid to correspond to the flow transmittance at the point in time when the flow transmittance F constitutes a valley point on the filtered signal which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, a good indication is given to when the debinding process is soon to be finished.

[0022] By choosing Ti > 45 min, the risk of initial start-up noise in the information signal impacting the determination of when the debinding process is finished is reduced.

[0023] The second predetermined time period T2 is preferably determined by the sampling frequency of the information unit. By having T2 = O.ls-lOOs, the fluctuation over a sufficient amount of measuring points, e.g. 100 measuring points, when using a conventional information unit, is determined.

[0024] By determining if the fluctuation is equal to or less than 1-2% over the second predetermined time period T2, a clear indication of when the flow transmittance has reached a steady state is given due to the reduced risk of noise in the signal.

[0025] By activating the steady state function repeatedly, subsequent to the time tcontroi, several attempts are made to determine when the flow transmittance has reached a steady state. Thereby, the determination of when the flow transmittance has reached a steady state is improved. Further, the processing power required to determine when the flow transmittance has reached a steady state is reduced compared to if the steady state function would be continuously running.

[0026] By having n = 3-7, preferably n = 4-6, more preferably n = 5, the determination of when the flow transmittance F has reached a steady state is further improved since the determination of when the flow transmittance has reached a steady state is made close to the actual point in time when the steady state is reached while the processing power required to make the determination is hold to a minimum.

[0027] The flow transmittance F of the pressure regulating valve is preferably adjustable between 0% and 100%, wherein a flow transmittance of 0% indicates that the pressure regulating valve is completely closed, and wherein a flow transmittance of 100% indicates that the pressure regulating valve is completely open.

[0028] The information unit is any type of unit suitable for generating the information signal. The information unit is e.g. a sensor or a part of a control unit for the sintering furnace.

[0029] The analysis unit is any type of unit suitable for analyzing the information signal, e.g. a separate computer or a part of a control system for the sintering furnace.

[0030] The organic additives are preferably binding material such as polyethylene glycol (PEG). The cutting element is preferably a cutting element for performing a metal cutting operation.

[0031] According to an embodiment, the cutting element is a cubic boron nitride (CBN) cutting element, a polycrystalline diamond (PCD) cutting element, a cemented carbide cutting element, a cermet cutting element, or a ceramic cutting element.

[0032] According to an embodiment, the cutting element is any of a cutting insert, a drill, an end mill, a boring tool, or a reamer.

[0033] According to an embodiment, the signal filter is a Savitsky-Golay filter.

[0034] By using a Savitsky-Golay filter, the signal-to-noise ratio is further improved. The determination of when the debinding process is finished is thereby further improved.

[0035] According to an embodiment, the system further comprises a user interface operatively connected to the analysis unit, wherein the analysis unit is further configured to perform the step of:

[0036] -presenting that the process of removal of organic additives from the green body is finished via the user interface.

[0037] By presenting that the debinding process is finished via the user interface, the operator of the sintering furnace is informed about that the debinding process is finished. The operator can then terminate the debinding process when it is determined that said process is finished.

[0038] The user interface is any type of user interface suitable for presenting that the debinding process is finished, e.g. a monitor, a display or a loudspeaker.

[0039] According to an embodiment, the system further comprises a control unit for the sintering furnace, wherein the control unit is operatively connected to the sintering furnace and is configured to control the operation of the sintering furnace, wherein the control unit is operatively connected to the analysis unit, wherein the analysis unit is further configured to perform the steps of:

[0040] -generating a finishing signal indicating that the process of removal of organic additives from the green body is finished; and

[0041] -transmitting the finishing signal to the control unit; and wherein the control unit is configured to terminate the process of removal of organic additives from the green body in response to the finishing signal.

[0042] According to an embodiment, the control unit and the analysis unit are both part of a control system for the sintering furnace.

[0043] By transmitting the finishing signal to the control unit, the control unit can automatically terminate the debinding process when it is determined that said process is finished.

[0044] The object of the present invention is further achieved by means of a method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished, wherein the method is performed by the system described above, wherein the method comprises the steps of:

[0045] -receiving the information signal from the at least one information unit;

[0046] -generating a filtered signal by applying a signal filter to the received information signal;

[0047] -determining a point in time tcontroi when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time to, wherein the time to is a point in time when the flow transmittance F constitutes a valley point on the filtered signal which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein Ti > 45 min, and wherein the time tcontroi is subsequent to the time t0;

[0048] -activating a steady state function at the time tcontroi, wherein the steady state function is configured to determine a fluctuation D of the flow transmittance F over a second predetermined time period T2, wherein T2= O.ls-lOOs, preferably T2= ls-20s;

[0049] -determining if the flow transmittance F has reached a steady state by determining if the fluctuation D is equal to or less than a predetermined threshold fluctuation Dthreshoid, wherein Dthreshoid = 1-2%;

[0050] -activating the steady state function every n:th minute subsequent to the time tcontroi until the flow transmittance F has reached a steady state, wherein n = 3-7, preferably n = 4-6, more preferably n = 5; and

[0051] -determining that the process of removal of organic additives from the green body is finished when the flow transmittance F has reached the steady state.

[0052] According to an embodiment, the method further comprises the step of:

[0053] -presenting that the process of removal of organic additives from the green body is finished via the user interface.

[0054] According to an embodiment, the method further comprises the steps of:

[0055] -generating a finishing signal indicating that the process of removal of organic additives from the green body is finished;

[0056] -transmitting the finishing signal to the control unit; and

[0057] -terminating the process of removal of organic additives from the green body in response to the finishing signal.

[0058] The object of the present invention is further achieved by means of a computer program comprising computer readable code means to be run in the system described above, which computer readable code means when run in the system causes the system to perform the method described above. The object of the present invention is further achieved by means of a carrier containing the computer program described above, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 schematically illustrates a system for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished according to an embodiment of the invention.

[0061] Figure 2 schematically illustrates an example of an information signal generated by the information unit in the system illustrated in figure 1, and a filtered signal generated by the analysis unit in the system illustrated in figure 1.

[0062] Figure 3 illustrates a flowchart of a method for determining when a process of removal of organic additives from a green body during manufacturing of a cutting element is finished according to an embodiment of the invention.

[0063] DETAILED DESCRIPTION

[0064] The disclosed embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that the disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numbers refer to like elements throughout. The elements illustrated in the drawings are not necessary according to scale. Some elements might have been enlarged in order to clearly illustrate those elements.

[0065] Figure 1 schematically illustrates a system (100) for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished according to an embodiment of the invention. The system (100) comprises a sintering furnace (110) having a pressure regulating valve (112). A plurality of green bodies (102) is placed on a sintering plate (104) in the sintering furnace (110). The pressure regulating valve (112) has an adjustable flow transmittance F, c.f. figure 2, wherein the pressure regulating valve (112) is configured to regulate the pressure within the sintering furnace (110) by adjusting the flow transmittance F. The system (100) further comprises a control unit (120) for the sintering furnace (110) in form of a computer, which is operatively connected to the sintering furnace (110) and is configured to control the operation of the sintering furnace (110). The control unit (120) comprises an information unit (122), which is operatively connected to the sintering furnace (110). The information unit (122) is configured to generate an information signal (124) comprising information regarding the flow transmittance F as a function of time t, c.f. figure 2. The system (100) further comprises an analysis unit (130) in form of a computer, which is operatively connected to the control unit (120) including the information unit (122). The analysis unit (130) comprises a user interface (132) in form of a monitor. In figure 1, the analysis unit (130) and the control unit (120) are illustrated as two separate computers. Alternatively, the analysis unit (130) and the control unit (120) are two parts of the same computer.

[0066] Figure 2 schematically illustrates an example of an information signal (124) generated by the information unit (122), and a filtered signal (134) generated by the analysis unit (130). The time tcontroi is a point in time when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time to, wherein the time to is a point in time when the flow transmittance F constitutes a valley point on the filtered signal (134) which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein the time tControi is subsequent to the time t0.

[0067] Figure 3 illustrates a flowchart of a method (200) for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished, wherein the method (200) is performed by the system (100) described above, wherein the method (200) comprises the steps of:

[0068] -receiving (202) the information signal (124) from the at least one information unit (122);

[0069] -generating (204) a filtered signal (134) by applying a signal filter to the received information signal (124);

[0070] -determining (206) a point in time tcontroi when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time t0, wherein the time t0is a point in time when the flow transmittance F constitutes a valley point on the filtered signal (134) which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein Ti > 45 min, and wherein the time tcontroi is subsequent to the time to;

[0071] -activating (208) a steady state function at the time tcontroi, wherein the steady state function is configured to determine a fluctuation D of the flow transmittance F over a second predetermined time period T2, wherein T2 = O.ls-lOOs, preferably T2 = ls-20s;

[0072] -determining (210) if the flow transmittance F has reached a steady state by determining if the fluctuation D is equal to or less than a predetermined threshold fluctuation Dthreshoid, wherein Dthreshoid = 1-2%;

[0073] -activating (212) the steady state function every n:th minute subsequent to the time tcontroi until the flow transmittance F has reached a steady state, wherein n = 3-7, preferably n = 4-6, more preferably n = 5;

[0074] -determining (214) that the process of removal of organic additives from the green body (102) is finished when the flow transmittance F has reached the steady state;

[0075] -presenting (216) that the process of removal of organic additives from the green body (102) is finished via the user interface (132); -generating (218) a finishing signal indicating that the process of removal of organic additives from the green body (102) is finished;

[0076] -transmitting (220) the finishing signal to the control unit (120); and

[0077] -terminating (222) the process of removal of organic additives from the green body (102) in response to the finishing signal.

[0078] Figure 3 illustrates an example of method steps. The method may comprise additional steps. Some of the method steps can be performed simultaneously. The method steps can be performed in a different order.

[0079] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

CLAIMS1. A system (100) for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished, wherein the system (100) comprises a sintering furnace (110) having a pressure regulating valve (112), wherein the pressure regulating valve (112) has an adjustable flow transmittance F, wherein the pressure regulating valve (112) is configured to regulate the pressure within the sintering furnace (110) by adjusting the flow transmittance F, wherein the system (100) further comprises at least one information unit (122) operatively connected to the sintering furnace (110), wherein the information unit (122) is configured to generate an information signal (124) comprising information regarding the flow transmittance F as a function of time t, and wherein the system (100) further comprises an analysis unit (130) operatively connected to the at least one information unit (122), wherein the analysis unit (130) is configured to perform the following steps:-receiving the information signal (124) from the at least one information unit (122);-generating a filtered signal (134) by applying a signal filter to the received information signal (124);-determining a point in time tcontroi when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time to, wherein the time to is a point in time when the flow transmittance F constitutes a valley point on the filtered signal (134) which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein Ti > 45 min, and wherein the time tcontroi is subsequent to the time to;-activating a steady state function at the time tcontroi, wherein the steady state function is configured to determine a fluctuation D of the flow transmittance F over a second predetermined time period T2, wherein T2= O.ls-lOOs, preferably T2= 1S-20S;-determining if the flow transmittance F has reached a steady state by determining if the fluctuation D is equal to or less than a predetermined threshold fluctuation Dthreshoid, wherein Dthreshoid = 1-2%;-activating the steady state function every n:th minute subsequent to the time tcontroi until the flow transmittance F has reached a steady state, wherein n = 3-7, preferably n = 4-6, more preferably n = 5; and-determining that the process of removal of organic additives from the green body (102) is finished when the flow transmittance F has reached the steady state.

2. The system (100) according to claim 1, wherein the signal filter is a Savitsky-Golay filter.

3. The system (100) according to claim 1 or 2, wherein the system (100) further comprises a user interface (132) operatively connected to the analysis unit (130), wherein the analysis unit (130) is further configured to perform the step of:-presenting that the process of removal of organic additives from the green body (102) is finished via the user interface (132).

4. The system (100) according to any of the preceding claims, wherein the system (100) further comprises a control unit (120) for the sintering furnace (110), wherein the control unit (120) is operatively connected to the sintering furnace (110) and is configured to control the operation of the sintering furnace (110), wherein the control unit (120) is operatively connected to the analysis unit (130), wherein the analysis unit (130) is further configured to perform the steps of:-generating a finishing signal indicating that the process of removal of organic additives from the green body (102) is finished; and-transmitting the finishing signal to the control unit (120); and wherein the control unit (120) is configured to terminate the process of removal of organic additives from the green body (102) in response to the finishing signal.

5. A method (200) for determining when a process of removal of organic additives from a green body (102) during manufacturing of a cutting element is finished, wherein the method (200) is performed by the system (100) according to any of claims 1-4, wherein the method (200) comprises the steps of:-receiving (202) the information signal (124) from the at least one information unit (122);-generating (204) a filtered signal (134) by applying a signal filter to the received information signal (124);-determining (206) a point in time tcontroi when the flow transmittance F drops below a threshold transmittance Fthreshoid, wherein the threshold transmittance Fthreshoid corresponds to the flow transmittance F at a time to, wherein the time to is a point in time when the flow transmittance F constitutes a valley point on the filtered signal (134) which is followed by an increasing flow transmittance F for at least a first predetermined time period Ti, wherein Ti > 45 min, and wherein the time tcontroi is subsequent to the time to;-activating (208) a steady state function at the time tcontroi, wherein the steady state function is configured to determine a fluctuation D of the flow transmittance F over a second predetermined time period T2, wherein T2 = O.ls-lOOs, preferably T2= 1S-20S;-determining (210) if the flow transmittance F has reached a steady state by determining if the fluctuation D is equal to or less than a predetermined threshold fluctuation Dthreshoid, wherein Dthreshoid = 1-2%;-activating (212) the steady state function every n:th minute subsequent to the time tControi until the flow transmittance F has reached a steady state, wherein n = 3-7, preferably n = 4-6, more preferably n = 5; and-determining (214) that the process of removal of organic additives from the green body (102) is finished when the flow transmittance F has reached the steady state.

6. The method (200) according to claim 5, wherein the method (200) further comprises the step of:-presenting (216) that the process of removal of organic additives from the green body (102) is finished via the user interface (132).

7. The method (200) according to claim 5 or 6, wherein the method (200) further comprises the steps of:-generating (218) a finishing signal indicating that the process of removal of organic additives from the green body (102) is finished;-transmitting (220) the finishing signal to the control unit (120); and -terminating (222) the process of removal of organic additives from the green body (102) in response to the finishing signal.

8. A computer program comprising computer readable code means to be run in the system (100) according to any of claims 1-4, which computer readable code means when run in the system (100) causes the system (100) to perform the method (200) according to any of claims 5-7.

9. A carrier containing the computer program according to claim 8, wherein the carrier is one of an electronic signal, optical signal, radio signal or computer readable storage medium.

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