Patent Description:
Monitoring essential parts of, e.g., tools or machines requires the acquisition of sensor data that are meaningful for process reliability and/or functionality of the part. To this end, it is already known to embed sensors such as thermocouples in such parts. This allows the temperature of the part to be measured so that malfunction or damage can be detected at an early stage and corrected if possible.

In many cases, the parts to be monitored are under high load conditions, e.g. high operating temperatures, high thermal cycling, high mechanical loading, strong vibrations, etc. Such conditions often impair or degrade the interface between the part and the sensor, thereby rendering the monitoring slower or unreliable. Further, conventional techniques often do not provide for sufficient design variability for placing the sensor near critical locations or surfaces of the part due to required space and/or reduction of part performance.

<CIT> discloses embedding a gauge in a gauge cavity portion of an additive manufactured part by affixing the gauge to the material of the part by gluing.

<CIT> discloses an article for use in a gas turbine engine. The article includes a multi-layer wall structure and an embedded sensor bonded to the wall structure.

<CIT> discloses a method of embedding a sensor in a 3D-printed SiC part.

<CIT> describes a sensor-equipped part comprising a metal body and a channel extending into and ending in the metal body. A cured material holds the sensor in place in the channel.

According to an aspect of the disclosure a sensor-equipped part includes a metal body and a first channel extending into and ending in the metal body. The sensor-equipped part further includes a second channel extending into the metal body and connecting to the first channel at a junction near the end of the first channel. A sensor is disposed in the first channel and a curable material in its cured state holds the sensor in place in the first channel. The second channel is configured to allow the curable material to be introduced through the junction into the first channel.

According to another aspect of the disclosure a method of manufacturing a sensor-equipped part includes forming a first channel in a metal body, the first channel extending into and ending in the metal body. A second channel extending into the metal body and connecting to the first channel at a junction near the end of the first channel is formed in the metal body. A sensor is disposed in the first channel. A curable material is introduced via the second channel into the first channel to embed at least a portion of the sensor. The curable material is cured to hold the sensor in place in the first channel.

The features of the various illustrated examples can be combined unless they exclude each other and/or can be selectively omitted if not described to be necessarily required. Examples are depicted in the drawings and are exemplarily detailed in the description which follows.

As used in this specification, layers or elements illustrated as adjacent layers or elements do not necessarily be directly contacted together; intervening elements or layers may be provided between such layers or elements. However, in accordance with the disclosure, elements or layers illustrated as adjacent layers or elements may in particular be directly contacted together, i.e. no intervening elements or layers are provided between these layers or elements, respectively.

The words "over" or "beneath" with regard to a part, element or material layer formed or located or disposed or arranged or placed "over" or "beneath" a surface may be used herein to mean that the part, element or material layer be located (e.g. placed, formed, arranged, disposed, placed, etc.) "directly on" or "directly under", e.g. in direct contact with, the implied surface. The word "over" or "beneath" used with regard to a part, element or material layer formed or located or disposed or arranged or placed "over" or "beneath" a surface may, however, either be used herein to mean that the part, element or material layer be located (e.g. placed, formed, arranged, deposited, etc.) "indirectly on" or "indirectly under" the implied surface, with one or more additional parts, elements or layers being arranged between the implied surface and the part, element or material layer.

<FIG> illustrates a cross-sectional view of an exemplary metal body <NUM>. The metal body <NUM> may be a part based on or made of, e.g., iron, steel, aluminum, titanium, copper, nickel or cobalt or an alloy of any of these metals.

The metal body <NUM> may form a component (e.g. insert, transmission, actuator, etc.) or the entirety of a mechanical equipment such as, e.g., a tool or a machine. In particular, the metal body <NUM> may form a tool or tool insert for High Pressure Die Casting (HPDC), Low Pressure Die Casting (LPDC) or Plastic Injection Moulding (PIM). Other applications are specifically components of apparatus used in the oil and/or gas industry. In operation, the metal body <NUM> may be subjected to high load conditions, e.g. high operating temperatures, high thermal cycling, high mechanical loading, strong vibrations, etc..

The metal body <NUM> is provided with a first channel <NUM> and a second channel <NUM>. The first channel <NUM> opens at, e.g., a first surface 110A of the metal body <NUM>. The first channel <NUM> extends into the metal body <NUM> and terminates at an end <NUM> of the first channel <NUM> within the metal body <NUM>.

Similarly, the second channel <NUM> is open and accessible at a surface of the metal body <NUM>, e.g. at the same first surface 110A as the first channel <NUM>. The second channel <NUM> extends into the metal body <NUM> and connects to the first channel <NUM> at a junction <NUM> located near the end <NUM> of the first channel <NUM>.

The end <NUM> of the first channel <NUM> may, e.g., be close to a second surface 110B of the metal body <NUM>. The second surface 110B may, e.g., be a functional surface of the part <NUM> (see e.g. <FIG>). The meaning of the term "functional surface" may comprise, inter alia, a working surface of a tool or machine part (such as, e.g., a punching tool, a die, an actuator, etc.) or a forming surface of a tool or tool insert (such as, e.g., a die casting mold or a plastic injection mold) or an effective surface of a machine part (such as, e.g., a turbine blade surface, etc.) or, e.g., a manifold for oil and gas industry.

A distance D1 between the functional surface 110B and the end <NUM> of the first channel <NUM> may, e.g., be in a range between <NUM> and <NUM>. In specific cases, where to sensor <NUM> is intended to be placed close to the functional surface 110B, the distance D1 may, e.g., be in a range between <NUM> and <NUM>, more specifically between <NUM> and <NUM> or <NUM> and <NUM>. As will be discussed in further detail below, the smaller the distance D1, the more accurate and faster the sensor measurement (e.g., temperature measurement), but increasing mechanical stress may occur in the residual wall between the end <NUM> of the first channel <NUM> and the second surface 110B, which may ultimately prevent further reduction of D1.

For example, for plastic injection molding tools a distance D1 of about <NUM> may be feasible, while for high pressure die casting, the operation of the tool may require a wall thickness D1 of about <NUM>.

A distance D2 between the end <NUM> of the first channel <NUM> and the junction <NUM> (more specifically, the upper end of the mouth of the second channel <NUM> into the first channel <NUM>) may preferably be in the range between <NUM> and <NUM>, for example. Although the distance D2 may also be zero, a minimum distance D2 of, e.g., <NUM> helps to avoid that the sensor <NUM> (see <FIG>) may inadvertently enter the second channel <NUM> and becomes misplaced when inserted into the first channel <NUM>. On the other hand, at greater distances from D2 approaching, for example, <NUM>, it may become difficult to avoid entrapped air at the end <NUM> of the first channel <NUM> when introducing the curable material <NUM> (see <FIG>).

In <FIG>, the first channel <NUM> is straight along its entire length, for example. However, as will be described further below, it is also possible that the first channel <NUM> is curved along at least a portion of its extension, for example.

The second channel <NUM> is in communication with the first channel <NUM> at the junction <NUM>. The first channel <NUM> and the second channel <NUM> may, e.g., be inclined with respect to each other at an angle of equal to or less than or greater than <NUM>° or <NUM>° or <NUM>° or <NUM>° at the junction <NUM>. In <FIG> the angle is denoted by α and refers to the angle between the axes of the first and second channels <NUM>, <NUM> at their point of intersection. The smaller the angle α the better is the filling behavior of the first channel <NUM> by curable material as described further below with reference to <FIG>. Further, it is less likely that the sensor <NUM> may inadvertently enter the second channel <NUM> and becomes misplaced when inserted into the first channel <NUM>.

In the example of <FIG> the second channel <NUM> may include a curved or bent portion <NUM> that allows the second channel <NUM> to approach the first channel <NUM>. This optional bent portion <NUM> may have a radius equal to or greater than, e.g., <NUM>. In other examples the second channel <NUM> may be substantially straight along its entire extension. In this case, the second channel <NUM> may open obliquely to the first surface 110A, for example.

A cross-sectional area of the first channel <NUM> may be greater than a cross-sectional area of the second channel <NUM>. By way of example, the second channel <NUM> may have a cross-sectional area equal to or greater than a disc-shape of a diameter of <NUM> or <NUM> or <NUM>. The first channel <NUM> may have a cross-sectional area equal to or greater than a disc-shape of a diameter of e.g. <NUM> or <NUM> or <NUM>. A maximum cross-sectional area of the first channel <NUM> may correspond to a disc-shape of diameter <NUM> and/or a maximum cross-sectional area of the second channel <NUM> may correspond to a disc-shape of diameter <NUM>.

The cross-sections of the first channel <NUM> and/or the second channel <NUM> may but need not to be circular disc-shaped. Further, the cross-sectional shape of the first and/or second channels <NUM>, <NUM> may but do not need to have a constant cross-sectional shape along their longitudinal extension. It is also possible that the cross-sectional shape varies along the longitudinal extension, e.g. may be larger near the entrance of the channels <NUM>, <NUM> and then tapers down to final cross-sectional shape. The figures recited above with respect to the cross-sectional area may, e.g., apply as minimum or maximum cross sectional area quantities along the respective channel extension.

As mentioned above, <FIG> illustrates the metal body <NUM> with a sensor <NUM> inserted into the first channel <NUM>. The sensor <NUM> may be a thermocouple configured for temperature measurement. In other examples, the sensor <NUM> may be a pressure sensor or an acceleration sensor or an positional sensor or an optical sensor, etc..

The sensor <NUM> has a sensor tip <NUM>. The sensor tip <NUM> may, e.g., be placed in contact (abutment) to the end <NUM> of the first channel <NUM>.

The first channel <NUM> may end in a dome of a rounded shape. The dome of a rounded shape provides for self-centering of the sensor <NUM> during integration. In other words, a dome of rounded shape at the end <NUM> of the first channel <NUM> helps to position the sensor <NUM> accurately in a defined and reproducible position which may be closest to the (functional) second surface 110B. Further, the rounded shape of the dome at the end <NUM> of the first channel <NUM> provides for a better stress distribution (stability) under load and for improved filling behavior of the first channel <NUM>, as will be described in the following.

In one example, the dome may have a continuous rounded or, for example, spherical shape. The transition between the rounded dome and the sidewall of the first channel <NUM> may be with or without a kink.

Referring to <FIG> illustrating another exemplary design of the dome, the dome may include or be composed of a conical portion <NUM> and a rounded cap portion <NUM>. The conical portion <NUM> may be, e.g., straight. An angle between a normal to the channel wall and the conical portion <NUM> may be, e.g., in a range between <NUM> and <NUM>°, and in particular, for example, about <NUM>° (see <FIG>). The transition between the conical portion <NUM> and the side wall of the first channel <NUM> may be, e.g., with or without a kink. Such design supports self-centering and generates less stress in the metal body <NUM> compared to sharp-edged, drilled holes.

Further, the wall surface of the dome may be formed with a greater roughness than the wall surface of the side wall of the first channel <NUM>. It has been shown that a greater roughness in the dome improves contact with the sensor <NUM>. For example, the roughness Ra of the wall surface of the dome may be in a range between <NUM> and <NUM>. For example, excellent results were obtained with Ra = <NUM>. The roughness of the side wall surface of the first channel <NUM> (and also, for example, of the second channel <NUM>) may be equal to or less than <NUM>, with an exemplary value of, e.g., Ra = <NUM>-<NUM>. The roughness Ra was measured according to standard DIN EN ISO <NUM>.

Referring to <FIG>, a curable material <NUM> is used to hold the sensor <NUM> in place in the first channel <NUM>. The second channel <NUM> is configured to allow the curable material <NUM> to be introduced through the junction <NUM> into the first channel <NUM>.

More specifically, e.g. after disposing the sensor <NUM> in the first channel <NUM>, the curable material <NUM> is introduced via the second channel <NUM> into the first channel <NUM>. Since the junction <NUM> of the first channel <NUM> and the second channel <NUM> is close to the end <NUM> of the first channel <NUM>, the curable material <NUM> enters into the first channel <NUM> near the tip <NUM> of the sensor <NUM>. The curable material <NUM>, in its uncured state, is liquid or plastically deformable so as to embed the sensor <NUM> to all sides at least at its upper portion and, optionally, along its entire length within the first channel <NUM>.

The curable material <NUM>, in its uncured state, can be injected into the second channel <NUM> at the opening of the second channel <NUM> in the first surface 110A of the metal body <NUM>. In its uncured state, during filling into the second channel <NUM>, the curable material <NUM> may have a high viscosity.

Due to the provision of the second channel <NUM>, at least an upper portion of the first channel <NUM> may be completely filled by the curable material <NUM> without the formation of voids in the curable material <NUM>. Voids (e.g. air pockets) would significantly decrease the mechanical stability and robustness of the fitting of the sensor <NUM> in the metal body <NUM> and could degrade the sensor function due to, e.g., reduced sensory (e.g. thermal or mechanical) contact.

As shown in <FIG>, the mouth of the second channel <NUM> into the first channel <NUM> at junction <NUM> may be positioned such that the tip <NUM> of the sensor <NUM> is located above the upper end of the mouth, i.e. above the junction <NUM>.

The curable material <NUM> may, e.g., be based on cement or another curable compound such as, e.g., glue, silicone, etc. The curable material <NUM> may optionally include metal filler particles. However, the metal content may be equal to or less than <NUM>% in volume. Preferably, the curable material <NUM> (e.g. cement) is non-metallic at all. For instance, the thermal conductivity of the curable material <NUM> in its cured (i.e. solidified) state may be in a range of <NUM> to <NUM> W/(m*K).

The CTE (Coefficient of Thermal Expansion) of the curable material <NUM>, in its cured (solidified) state, may be equal to or greater than the CTE of the metal material of the metal body <NUM>. This feature may lead to better heat transfer from the metal body <NUM> to e.g. a temperature sensor <NUM> and therefore more sensitive sensory information.

After the curable material <NUM> has been introduced via the second channel <NUM> into the first channel <NUM> to embed at least a portion of the sensor <NUM>, the curable material <NUM> is cured (solidified) to hold the sensor in place in the first channel <NUM>. By curing the curable material <NUM>, the sensor <NUM> may be anchored unmovably and, e.g., permanently (i.e. non-detachably) in the first channel <NUM>.

Curing (i.e. solidifying) of the curable material <NUM> may, e.g., be caused by heating and/or by chemical cross-linking depending on the nature of the curable material <NUM>.

It is to be noted that the sensor <NUM> need not be welded or otherwise secured to the end <NUM> of the first channel <NUM> to be held in place. In particular, the curable material <NUM> may be, for example, the only fastening means to hold the sensor <NUM> in place in the first channel <NUM>.

For example, the sensor <NUM> may be a temperature sensor, e.g., a sheath thermocouple. Temperature monitoring can be improved because it is not based on a point contact between the temperature sensor <NUM> and the wall of the first channel <NUM>, but a defined and time constant thermal contact between these two elements is ensured. This facilitates accurate and timely tracking of temperature changes, especially when the part <NUM> is subjected to movement, vibration or shock.

The first and/or second channels <NUM>, <NUM> may be formed by conventional machining, e.g. drilling and/or etching. In other examples, the first and/or second channels <NUM>, <NUM> are formed during manufacturing of the part <NUM>. For example, the metal body <NUM> may be formed by additive manufacturing (AM). Especially, the metal body <NUM> may be formed by powder bed fusion AM. Fe-based powders (e.g. Uddeholm CORRAX, BÖHLER W360 AMPO) or Al-based powders may be used, for example.

AM offers a high degree of design freedom and therefore allows to create bent or curved channel designs and/or channel designs with varying cross-sectional shape along their longitudinal extension (the cross-sectional area may, e.g., be widened near the entrance of the channels <NUM>, <NUM>) and/or channel designs with small cross-sectional areas as described above (which can often not be manufactured by drilling) and/or junctions <NUM> or channel ends <NUM> of rounded shapes.

More complex channel designs are illustrate in <FIG>, for example. In <FIG> the second channel <NUM> has a bent portion or curve <NUM>, which may be bent by an angle of, e.g., equal to or greater than <NUM>° or <NUM>° or <NUM>°. This allows the first channel <NUM> and the second channel <NUM> to be arranged a short distance apart.

Referring to <FIG>, the first channel <NUM> and/or the second channel <NUM> may be bent or non-linear shaped along a substantial or majority part of their length. Such complex design may be optimized to position the tip <NUM> of the temperature sensor <NUM> at a desired location, e.g. at a location near the (functional) second surface 110B that is particularly critical with regard to operational safety or real-time process monitoring. In other examples, the desired tip location may be in a central part of the metal body <NUM>.

Moreover, as illustrated in <FIG>, a bent design of the first channel <NUM> and/or the second channel <NUM> may be advantageous to position the tip <NUM> of the sensor <NUM> in the vicinity of a cooling media channel <NUM>. That way, cooling media channel clogging or other faults in a cooling system can be detected at an early stage so that the operation of the tool or a machine part can be stopped in good time before damage occurs. It is to be noted that the description above in relation to the distance D1 between the tip <NUM> of the sensor <NUM> and a functional surface 110B of the metal body may analogously apply to a distance between the tip <NUM> of the sensor <NUM> and a the cooling media channel <NUM> (or even any other structure implemented in metal body <NUM>). Therefore, to avoid reiteration, reference is made to the above description in terms of positioning the tip <NUM> close to a cooling media channel <NUM> or, e.g., any other structure implemented in metal body <NUM>.

Generally, non-linear, bent, curved or tortuous channel courses may be helpful in introducing less additional stress into the metal body <NUM> when designing around existing structures, such as e.g. cooling media channels <NUM>, and/or when positioning the tip <NUM> as close as possible to a particular location further into the metal body <NUM> or, for example, close to a functional surface 110B thereof. The bending can occur in one or different dimensions, i.e. relative to one, two or more sectional planes.

<FIG> illustrates a flowchart of an exemplary process to manufacture a sensor-equipped part. At S1 a first channel is formed in a metal body, wherein the first channel extends into and ends in the metal body.

At S2 a second channel is formed in the metal body, the second channel extending into the metal body and connecting to the first channel at a junction near the end of the first channel.

S1 and S2 may be carried out during AM of the metal body or after manufacturing of the metal body by conventional machining such as, e.g., drilling and/or etching. S1 and S2 can be carried out at the same time (in particular, e.g., during AM) or sequentially in any order, i.e. S1 before S2 or S2 before S1.

At S3 the sensor is disposed in the first channel. This may be done by entering the sensor into the opening of the first channel and pushing the sensor forward until its tip touches the end of the first channel.

At S4 a curable material is introduced in its liquid state via the second channel through the junction into the first channel. The curable material may embed at least a portion (e.g. at least the upper <NUM> or <NUM>) of the sensor on all sides.

At S5 the curable material is cured to hold the sensor in place in the first channel. Curing transfers the curable material from the liquid state to the solid state.

Claim 1:
A sensor-equipped part (<NUM>), comprising
a metal body (<NUM>);
a first channel (<NUM>) extending into and ending in the metal body (<NUM>);
a second channel (<NUM>) extending into the metal body (<NUM>) and connecting to the first channel (<NUM>) at a junction near the end of the first channel (<NUM>);
a sensor (<NUM>) disposed in the first channel (<NUM>); and
a curable material (<NUM>) in its cured state holding the sensor (<NUM>) in place in the first channel, wherein the second channel (<NUM>) is configured to allow the curable material (<NUM>) to be introduced through the junction into the first channel (<NUM>).