JP2010008231A - Crucible feeder mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To feed a crucible R with a simple configuration without damaging the crucible R, and to prevent displacement to a crucible installation part 33. <P>SOLUTION: A restriction structure 321 for lowering dropping speed of the crucible R, and reducing displacement of a landing position of the crucible R is provided on the delivery port side of a guide route 32 for guiding the crucible R to the crucible installation part 33 for receiving the crucible R. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is an element for analyzing elements such as carbon (C), nitrogen (N), hydrogen (H), sulfur (S), oxygen (O) contained in measurement samples such as steel, non-ferrous metals, and ceramics. More particularly, the present invention relates to a crucible supply mechanism for supplying a crucible.

  In this type of elemental analyzer, for example, as shown in Patent Document 1, a measurement sample is accommodated in a crucible sandwiched between an upper electrode and a lower electrode, and a voltage is applied to heat the measurement sample in the crucible. Then, the gas generated thereby is analyzed to analyze the elements of the measurement sample. And this elemental analyzer is equipped with the crucible supply mechanism which supplies a crucible, and the crucible supplied by the said crucible supply mechanism is conveyed on a lower electrode by a conveyance mechanism.

  Conventionally, a crucible supply mechanism is configured to drop a crucible from a crucible housing part that houses a plurality of crucibles through a guide path, and to install the crucible in a crucible installation part provided at a lower part of the guide path. The guide path is made larger than the outer diameter of the crucible so as to drop smoothly without clogging the crucible, and is formed by a cylindrical member having an equivalent cross section such as an acrylic pipe. That is, the passage cross-sectional area of the guide path is the same up to the exit.

  However, in such a case, there is a problem that the crucible is broken by an impact when landing on the crucible installation portion because the dropping speed increases as the crucible falls.

In addition, there is a problem that the landing position of the crucible varies within the range of the cross-sectional area of the guide path and deviates from a desired installation position. Furthermore, when transported by the transport mechanism thereafter, there is a problem that the crucible cannot be reliably gripped by the transport mechanism.
Japanese Patent No. 2949501

  Therefore, the present invention has been made to solve the above problems all at once, and while supplying a simple structure without damaging the crucible, it is possible to prevent displacement to the crucible installation portion. This is the main desired issue.

  That is, the crucible supply mechanism according to the present invention is a crucible supply mechanism used in an elemental analyzer that extracts and analyzes an element contained in a sample as a gas component by heating the sample placed in the crucible. A crucible installation part where the crucible is installed in order to transport the crucible to a predetermined heating position, and one end is opened as an introduction port for introducing the crucible, and the other end is opened above the crucible installation part. And a guide path for dropping the crucible and guiding it to the crucible installation portion, and a throttle structure for reducing the passage area of the crucible by reducing the cross-sectional area of the guide path is provided on the outlet side of the guide path. It is characterized by being.

  If this is the case, the crucible comes into contact with the throttle structure by reducing the cross-sectional area of the passage and narrowing the passage area while having a simple structure of providing a throttle structure on the outlet side of the guide path. The falling speed of the crucible can be reduced. In addition, since the crucible passage area is narrowed on the outlet side, it is possible to prevent displacement of the crucible at the installation position.

  In order to further simplify the structure of the throttle structure and to ensure a smooth drop of the crucible, it is desirable that the throttle structure includes a tapered portion that gradually narrows toward the outlet.

  In order to make it difficult for the crucible decelerated by the taper portion to accelerate again and to make the landing position of the crucible accurate, the throttle structure is continuously provided on the downstream side of the taper portion. It is desirable to provide a small-diameter portion having an equal cross-sectional shape having the same diameter as the minimum diameter.

  In order to make it possible to adjust the falling speed of the crucible in the small-diameter portion, it is desirable to provide an air hole provided in the small-diameter portion and communicating between the inside and the outside of the guide path. In this case, it is possible to adjust the falling speed of the crucible by controlling the amount of air discharged from the air holes or the amount of air introduced into the air holes.

  When the crucible installation part is connected to the guide path and moves up and down between a receiving position for receiving a dropped crucible and a spaced position spaced vertically downward from the receiving position, the crucible installation part In order to install the crucible to the head with higher accuracy, the crucible is provided with a positioning mechanism for positioning the outlet of the guide path and the crucible installation portion at the receiving position, and the positioning mechanism is the crucible installation portion or the guide. It is desirable to have a convex portion provided on one of the members forming the path, and a concave portion provided on the other of the members forming the crucible installation portion or the guide path and fitted to the convex portion.

  As described above, according to the present invention, it is possible to supply the crucible without damaging it while having a simple configuration, and to prevent the position shift to the crucible installation portion.

  Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic configuration diagram of the elemental analysis apparatus 100 of the present embodiment, FIG. 2 is a schematic cross-sectional view showing the configuration of the crucible supply mechanism 3, and FIG. 3 is a front view of the guide tube 5.

<Device configuration>
The elemental analysis apparatus 100 according to the present embodiment includes a metal sample contained in the crucible R by heating the metal sample (hereinafter also simply referred to as a sample) and analyzing a gas component generated at that time. The crucible supply mechanism for supplying the crucible R to be transported to the crucible transport mechanism 2, and the crucible transport mechanism 2 for transporting the crucible R to the analyzer main body 1. 3 is provided. Each will be described below.

<< Analyzer body 1 >>
The analyzer main body 1 will be described below. On the front surface of the analyzer main body 1, as shown in FIG. 1, an upper electrode 12 and a lower electrode 11 are provided vertically apart from each other, and a sample is placed on the lower electrode 11. It is comprised so that the crucible R which accommodated can be mounted. The crucible position placed on the lower electrode 11 shown in FIG. 1 is the heating position P1. In FIG. 1, reference numeral 13 denotes a detection sensor (for example, a photoelectric sensor) that detects the presence or absence of a crucible on the lower electrode 11. The crucible R is made of graphite having a cylindrical shape with an open top, and the lower end has a tapered shape. In addition, the crucible R may be one in which an annular concave groove is formed on the outer periphery of the lower end portion in addition to a taper shape whose lower end portion is tapered.

  At the time of analysis, the lower electrode 11 slides upward with respect to the crucible R placed at the heating position P <b> 1, and the crucible R is sandwiched between the upper electrode 12. In this state, when a sample is loaded into the crucible R from the sample loading port 12A provided above the upper electrode 12, a current is applied between the electrodes 11 and 12, and the crucible R generates heat to generate heat. The sample is heated. The gas generated from the heated sample is sent to an analysis unit (not shown) to measure the component, and the element originally contained in the sample is analyzed from the result.

  For example, when measuring the amount of oxygen in a sample, CO (carbon monoxide), which is a reaction product, is generated by melting the sample, and the CO is detected using, for example, a non-dispersive infrared detector that constitutes the analysis unit. Measure and calculate the amount of oxygen present in the sample based on the CO value. In addition, components such as hydrogen nitrogen can be measured by setting a reaction product and an analysis unit corresponding to the reaction product. After the analysis, the used crucible R is discarded together with the sample by the crucible transport mechanism 2.

<< Crucible transport mechanism 2 >>
As shown in FIG. 1, the crucible transport mechanism 2 transports a crucible R installed in a crucible installation section 33 to be described later to a heating position P1 in the analyzer main body 1, and a heating position P1 (lower electrode 11). The arm portion 21 is capable of moving forward and backward, a drive mechanism (not shown) for driving the arm portion 21, and a pair of gripping claws 22 attached to the tip of the arm portion 21. It is controlled by a command from a control device (not shown).

  A base end portion of the arm portion 21 is connected to a rotation shaft of a driving mechanism provided on the base 101, and the arm portion 21 is moved to a heating position P1 and a retracted position separated from the heating position P1 by the driving mechanism. Rotate between and move forward and backward. Here, the retracted position is located outside the crucible installation portion 33 with respect to the heating position P1. Further, at least one of the gripping claws 22 has, for example, a generally square shape. Each gripping claw 22 is slidably held on the arm portion 21 at the base end portion, and is slid so as to reduce the distance between the gripping claws 22 in response to a command from the control device. It is comprised so that the side peripheral surface of the said crucible R can be narrow-pressure-gripped between center parts.

  The operation of the crucible transport mechanism 2 will be described. During the crucible transport, the arm unit 2 rotates from the retracted position and reaches the crucible installation unit 33. Then, the gripping claws 21 grip the crucible R in the crucible installation part 33. Then, it rotates again and moves to the heating position P1, and the crucible R is placed on the heating position P1 (on the lower electrode 11). After placement, the arm unit 2 returns to the retracted position. Further, after the analysis, the arm portion 21 moves from the retracted position to the heating position P1, and the gripping claws 21 grip the crucible R on the lower electrode 11, transport it to a waste container (not shown), and discard it.

<< Crucible supply mechanism 3 >>
The crucible supply mechanism 3 automatically supplies the crucible R conveyed by the crucible conveyance mechanism 2, and as shown in FIG. 2, in particular, a crucible accommodating portion 31 capable of accommodating a plurality of crucibles R, and crucible accommodation. A guide path 32 for dropping the crucible R from the part 31 by its own weight, and a crucible installation part 33 for receiving the dropped crucible R provided at the outlet 32b (exit) of the guide path 32 are provided.

  The crucible container 31 holds an inclined surface 311 on which a plurality of crucibles R are placed in parallel, a discharge port 312 provided below the inclined surface 311, and a crucible R sliding down below the inclined surface 311. And a crucible discharge mechanism 313 that moves to the discharge port 312. As the crucible discharge mechanism 313, for example, a rotating body 3131 (see FIG. 1) that has a concave portion that accommodates the crucible R on the side surface and rotates around one axis, and a drive unit (not shown) that rotates the rotating body 3131. It is possible to move the crucible R accommodated in the concave portion to the discharge port 312 by rotating the crucible R. Then, the crucible R moved to the upper part of the discharge port 312 by the crucible discharge mechanism 313 falls from the discharge port 312 and is discharged by its own weight. In this case, since the crucibles R are accommodated in parallel, as many crucibles R as possible can be accommodated. Moreover, since it discharges using the dead weight of the crucible R, the structure of the discharge mechanism 313 can be simplified.

  The guide path 32 drops the crucible R in a substantially vertical direction and guides the crucible R to the crucible installation portion 33. As shown in FIGS. 2 and 3, the guide path 32 opens as an introduction port 32a for introducing the crucible R at one end. The other end opens above the crucible installation portion 33 as a lead-out port 32b for leading the crucible R. The guide path 32 of the present embodiment is formed in a substantially vertical direction by a guide tube 5 having a substantially cylindrical shape, and the introduction port 32 a of the guide path 32 communicates with the discharge port 312 of the crucible housing part 31.

  The guide path 32 is for dropping the crucible R introduced from the crucible housing part 31 in a vertically positive state, and when the crucible R falls, it has an inner diameter that does not turn upside down, for example, the longest of the crucible R. The inner diameter is smaller than the length of the diagonal.

  On the side wall of the guide tube 5, foreign matter other than the crucible R introduced from the discharge port 312 (for example, fragments of the crucible R) is discharged outside the guide tube 5 without reaching the outlet (outlet port 32 b). For example, one or a plurality of slit-like through holes 5A are provided (three in FIG. 3). Specifically, in the guide tube 5, a through hole 5 </ b> A is provided below the side wall of the bent portion 51 provided substantially perpendicular to the inclined surface 311. Thereby, the fragments are discharged out of the guide tube 5 through the through holes 5A by their own weight. Further, the clogging of the crucible R in the guide path 32 can be confirmed by the through hole 5A.

  Further, the guide path 32 is provided with a throttle structure 321 that exhibits a fall speed reduction function for reducing the fall speed of the crucible R and a position shift prevention function for preventing a position shift of the installation position to the crucible installation section 33. . The diaphragm structure 321 is provided on the guide port 32 on the outlet 32b side, and more specifically, is provided at a position where the drop speed reduction function and the positional deviation prevention function are exhibited. It is provided so as to be continuous with the outlet 32b.

  The throttle structure 321 reduces the passage cross-sectional area of the guide path 32 and narrows the passage area of the crucible R. Specifically, the throttle structure 321 is provided in the vicinity of the outlet of the guide path 32, and is continuously provided at the tapered portion 3211 that gradually narrows toward the outlet 32b and the outlet side end of the tapered portion 3211. A small-diameter portion 3212 having an equal cross-sectional shape having the same diameter as the minimum diameter of the tapered portion 3211.

  The minimum diameter of the taper portion 3211 (the inner diameter of the small diameter portion 3212) is slightly larger than the outer diameter of the crucible R, and the crucible R can pass by its own weight. Further, the small diameter portion 3212 is formed from the outlet side end of the tapered portion 3211 to the outlet 32b of the guide path 32. As a result, the crucible R passing through the small diameter portion 3212 falls in the posture installed in the crucible installation portion 33 (that is, the posture in which the central axis of the crucible R faces the substantially vertical direction).

  Due to the throttle structure 321, the crucible R comes into contact with the tapered portion 3211 in the middle of dropping, and contacts with the inner peripheral surface of the small diameter portion 3212. Due to the contact resistance, the crucible R falls at the outlet 32b of the guide path 32. Speed is reduced. Therefore, it is possible to prevent the crucible R from being damaged when landing on the crucible installation portion 33. Further, the small diameter portion 3212 has an inner diameter slightly larger than the outer diameter of the crucible R, and it is possible to prevent variation of the landing position on the crucible installation portion 33 and to prevent the displacement of the installation position, and to install with high accuracy. Can do.

  As shown in FIGS. 1 and 2, the crucible installation portion 33 is provided at the distal end portion of the drive shaft 341 of the elevating mechanism 34 formed of an air cylinder or the like provided on the base 101. The crucible installation unit 33 is connected to the guide path 32 and moves up and down between a receiving position Q1 that receives the crucible R that has fallen and a crucible conveying position Q2 that is a separated position vertically below the receiving position Q1. It is something that moves.

  Specifically, as shown in FIG. 2, the crucible installation portion 33 has a recess 331 x that can accommodate the crucible R, and is provided in the crucible receiving body 331 that receives the crucible R, and the recess 331 x of the crucible receiving body 331. And a mounting projection 332.

  The crucible receiving body 331 has a substantially bottomed cylindrical shape and is formed of a transparent resin that allows the inside to be visually recognized. The inner diameter of the concave portion 331x is larger than the outer diameter of the crucible R.

  The mounting protrusion 332 has a substantially cylindrical shape, and the diameter thereof is set to be slightly smaller than the opening diameter of the crucible R. The mounting protrusion 332 is provided coaxially in the recess 331x of the crucible receiving body 331. When the crucible R is installed in the vertical direction, the crucible R is placed on the substantially horizontal upper surface 332a. The On the other hand, the mounting protrusion 332 is accommodated in the crucible R when the crucible R is installed upside down. With this configuration, the height position of the crucible R in the crucible installation portion 33 differs between the case where the crucible R is installed in the upside down direction and the case where the crucible R is installed upside down.

  Further, the length of the mounting protrusion 332 is longer than any depth dimension in the various crucibles R used, and the size of the crucible R is not limited. That is, the length of the mounting protrusion 332 is a length that prevents the opening of the crucible R from coming into contact with the bottom surface of the recess when it is installed upside down. That is, the length of the mounting protrusion 332 is set such that a space is formed between the bottom surface of the recess and the opening end surface of the crucible R when installed in the upside down direction. Thereby, even if foreign matters such as fragments of the crucible R are accumulated in the recess 331x, the crucible receiving body 331 can accommodate the crucible R upside down.

  Further, as shown in FIGS. 1 and 2, the crucible supply mechanism 3 includes a crucible detection sensor 41 and constitutes the reversal detection mechanism 4 together with the crucible installation portion 33.

  The crucible detection sensor 41 uses light to detect the crucible R when the crucible R is installed on the mounting protrusion 332 in the vertical direction. Specifically, a photoelectric sensor is used, and the trajectory of the light L1 that exits the light emitting portion of the photoelectric sensor 41 and reaches the light receiving portion is the outer peripheral surface of the crucible R that is installed in the crucible installation portion 33 in the vertical direction. It is configured to reflect and reach the light receiving unit.

  With such a configuration, when the crucible R is installed vertically upward, the light L1 emitted from the light emitting unit is reflected by the side surface of the crucible R and received by the light receiving unit. On the other hand, when the crucible R is installed upside down, the light L1 emitted from the light emitting unit is not reflected by the outer peripheral surface of the crucible R and is not received by the light receiving unit. As described above, when the crucible R is not installed in the crucible installation unit 33, or when it is installed upside down even though it is installed, the light receiving unit does not receive the light L1. Inversion of the crucible R can be detected. Further, the detection signal of the light receiving unit is output to notifying means (not shown) so as to notify the operator with an alarm sound or the like. The crucible detection sensor 41 is not limited to the reflective type described above, and may be a transmissive type or a type using ultrasonic waves.

<< Positioning mechanism 6 >>
Furthermore, as shown in FIG. 2, the crucible supply mechanism 3 of the present embodiment includes a positioning mechanism 6 that positions the outlet 32 b of the guide path 32 and the crucible installation portion 33.

  The positioning mechanism 6 includes a convex portion 61 provided on one side of the crucible installation portion 33 or the guide tube 5, a concave portion 62 provided on the other side of the crucible installation portion 33 or the guide tube 5, and fitted with the convex portion 61. Consists of. In the state in which the convex portion 61 and the concave portion 62 are fitted, the central axis of the throttle structure 321 provided in the vicinity of the outlet 32b of the guide path 32 and the central axis of the crucible receiving body 331 (mounting protrusion 332) coincide with each other. Let

  Specifically, the convex portion 61 of the present embodiment has a tapered shape that decreases in diameter toward the tip, and is configured by a tapered portion 331 t formed at the upper end portion of the side peripheral wall of the crucible receiving body 331. Further, the recess 62 has an expanding taper shape that expands toward the tip, and is constituted by a tapered portion 5t formed around the outlet 32b of the guide tube 5.

  Then, as the crucible installation part 33 moves from the crucible transport position Q2 to the receiving position Q1, the taper part 331t of the crucible receiving body 331 is fitted and positioned in the taper part 5t of the guide tube 5, and the crucible installation part 33 is positioned. In a state where the receiving position Q1 has been reached, the central axis of the throttle structure 321, more specifically, the central axis of the small diameter portion 3212 and the central axis of the crucible receiving body 331 (mounting protrusion 332) coincide. In addition, by interposing an elastic body such as a spring between the crucible receiving body 331 and the drive shaft 341, an actuator with low positional accuracy such as an air cylinder can be used as the elevating mechanism 34.

  In addition, since the crucible R falls substantially coaxially with the small diameter portion 3212 of the throttle structure 321, the central axis of the crucible R and the central axis of the crucible receiving body 331 (mounting protrusion 332) substantially coincide with each other. The position accuracy of the crucible R installation on the crucible installation portion 33 can be made extremely accurate.

  <Effect of this embodiment>

  According to the elemental analysis device 100 according to the present embodiment configured as described above, the passage area is reduced by reducing the cross-sectional area of the passage while having a simple structure in which the throttle structure 321 is provided on the outlet 32b side of the guide path 32. By narrowing the crucible R, the crucible R can come into contact with the throttle structure 321, and the falling speed of the crucible R can be reduced. Further, since the passage area of the crucible R is narrowed on the outlet 32b side, it is possible to prevent the displacement of the crucible R at the landing position, and the crucible installation portion 33 can be installed with high accuracy.

  In addition, since the throttle structure 321 includes the tapered portion 3211 and the small diameter portion 3212, the configuration of the throttle structure 321 is simplified, the smooth fall of the crucible R is ensured, and the crucible R decelerated by the tapered portion 3211 is again provided. While making it difficult to accelerate, the landing position of the crucible R can be made more accurate.

  <Other modified embodiments>

  The present invention is not limited to the above embodiment. In the following description, the same reference numerals are given to members corresponding to the above-described embodiment.

  For example, in the above embodiment, only one throttle structure is provided on the outlet side of the guide path. However, as shown in FIG. 4, there are a plurality of throttle structures (three in FIG. 4). ) May be provided. In this case, except for the throttle structure 321 'provided closest to the outlet, the small diameter portion is not required and only the tapered portion may be used. In this case, every time the crucible R passes through each throttle structure 321 ′, the falling speed is reduced, so that it is possible to prevent breakage at the time of landing on the crucible installation portion 33, and the crucible R falls in the guide path 32 ′. At this time, it is possible to prevent the crucible R from being damaged by colliding with the inner peripheral surface of the guide tube 5 ′ forming the guide path 32 ′.

  Further, as shown in FIG. 5, the throttle structure 321 ′ may be provided with, for example, a plurality of protrusions extending radially in the passage direction on the inner peripheral surface of the guide tube 5 ′ forming the guide path 32 ′. At this time, each protrusion has a substantially wedge shape, and is continuously provided on the inclined portion 321a whose height gradually increases as it goes to the outlet, and on the outlet side end of the inclined portion 321a. , And a contour portion 321b having substantially the same height as the end portion on the outlet side.

  Furthermore, the diaphragm structure may be an inclined plane other than the tapered surface.

  In addition, the diaphragm structure of the above embodiment includes the tapered portion and the small diameter portion, but may include only the tapered portion.

  In addition, in the crucible supply mechanism of the above embodiment, the crucible installation part moves up and down, but the outlet of the guide tube (guide path) may move up and down.

  In addition, as shown in FIG. 6, an air hole provided in the small diameter portion 3212 and communicating between the inside and the outside of the guide path 32 may be provided. At this time, the air hole functions as air escape when the crucible R passes, and the crucible R can be smoothly dropped. In addition, by connecting a flow rate controller such as a needle valve to the air hole and controlling the amount of air discharged from the air hole or the amount of air introduced into the air hole 321H, the falling speed of the crucible R can be adjusted. can do.

  In addition, the guide path of the embodiment has a circular cross section, but may have a rectangular cross section, for example.

  In addition to the graphite crucible, a ceramic crucible may be used. In this case, the analyzer main body includes a high-frequency heating furnace, and may analyze carbon, sulfur, etc. present in the sample.

  In addition, some or all of the above-described embodiments and modified embodiments may be combined as appropriate, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. .

The typical block diagram of the elemental analyzer which concerns on one Embodiment of this invention. The longitudinal cross-sectional view which shows the structure of the crucible supply mechanism in the same embodiment. The front view of the guide tube in the embodiment. Sectional drawing which shows the aperture_diaphragm | restriction structure which concerns on deformation | transformation embodiment. The longitudinal cross-sectional view and cross-sectional view which show the modification of an aperture structure. The longitudinal cross-sectional view which shows the modification of an aperture_diaphragm | restriction structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Element analyzer R ... Crucible P1 ... Heating position 3 ... Crucible supply mechanism 33 ... Crucible installation part 32 ... Guide path 321 ... Drawing structure 3211 ... Tapered part 3212 ... Small diameter part 321H ... Air hole Q1 ... Receiving position Q2 ... Separation position 6 ... Positioning mechanism 61 ... Convex part 62 ... Concave part

Claims (5)

A crucible supply mechanism used in an elemental analysis device for extracting and analyzing an element contained in a sample as a gas component by heating a sample placed in a crucible,
A crucible installation section in which the crucible is installed to convey the crucible to a predetermined heating position;
One end is opened as an introduction port for introducing the crucible, the other end is opened above the crucible installation portion as a lead-out port for leading out the crucible, and the guide path for dropping the crucible and guiding it to the crucible installation portion; Comprising
A crucible supply mechanism in which a throttle structure is provided on the outlet side of the guide path to reduce the cross-sectional area of the guide path and narrow the passage area of the crucible.   The crucible supply mechanism according to claim 1, wherein the throttle structure includes a tapered portion that gradually narrows toward the outlet.   The crucible supply mechanism according to claim 2, wherein the throttle structure includes a small-diameter portion having an equal cross-sectional shape that is provided continuously downstream of the tapered portion and has the same diameter as the minimum diameter of the tapered portion.   The crucible supply mechanism according to claim 3, further comprising an air hole provided in the small-diameter portion and communicating between the inside and the outside of the guide path. The crucible installation part moves up and down between a receiving position that approaches the guide path and receives a crucible that has fallen, and a separated position that is spaced vertically downward from the receiving position,
A positioning mechanism for positioning the exit of the guide path and the crucible installation portion at the receiving position;
The positioning mechanism is provided on one of the crucible installation part or the member forming the guide path, and on the other of the crucible installation part or the member forming the guide path, and fitted with the projection. The crucible supply mechanism according to claim 1, 2, 3 or 4, wherein the crucible supply mechanism comprises a mating recess.