Mechanical seals for liquids with peripheral rim

Abstract

The present invention relates to a mechanical seal for liquid with an outer edge, comprising a dynamic ring and a static ring, wherein the ends of the dynamic ring and the static ring are sealing end faces which fit and rub against each other and are perpendicular to an axis, thereby isolating liquid on one side of the end faces from leaking to the other side, and at least one of the dynamic ring and the static ring is provided with an outer edge which is highly protruding on the liquid side and inclined toward the short ring, so that when the transmission equipment is running, liquid turbulence occurs at the inclined surface of the edge, and the centrifugal force generated keeps particles or impurities in the liquid away from the sealing end face, thereby effectively preventing particles or impurities in the liquid from entering the sealing surface, and increasing the ring body strength of the sealing ring, expanding the heat dissipation area of ​​the ring body, and significantly improving the liquid sealing effect and service life.

Description

Technical Field

[0001] The invention relates to a mechanical seal technology for liquids, in particular to a friction seal ring with two ring surfaces tightly attached and perpendicular to an axis, specifically to a dynamic and static mechanical seal ring for liquids with an outer edge. Background Art

[0002] In the prior art, there are four major types of fluid seals: packing seals, rubber seals, dry gas seals, and mechanical seals. Among them, packing seals (commonly known as packing seals) are mainly composed of packing, packing boxes, and packing fixings. Packing seals are sealed by applying pressure from fixings to plastically deform the packing to produce radial force and close contact with the shaft. Packing seals wear the shaft and leak a small amount. Among them, rubber ring seals are sealed by the high elasticity of rubber materials. When a small stress is applied, a large deformation will occur. This deformation can provide contact pressure, compensate for the leakage gap, and achieve the purpose of sealing. Rubber ring seals are mostly used for reciprocating hydraulic and pneumatic seals or almost pressure-free rotary oil seals; packing seals and rubber ring seals do not belong to mechanical seals. Mechanical seals are defined in the relevant national standards as follows: "A device for preventing fluid leakage, which is composed of at least one pair of end faces perpendicular to the axis of rotation, which are kept in contact and slide relative to each other under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the cooperation of auxiliary seals." Different from the first two types of seals, the sealing ring of the mechanical seal is made of rigid material, so it is necessary to compensate for the elastic force or magnetic force behind it; on the contrary, the elastic or filler material has a large resistance and cannot be designed and implemented according to the above national standards. Fluid mechanical seals can be divided into sealing ring contact seals and non-contact seals, among which non-contact mechanical seals are a special form of mechanical seals, namely dry gas seals, which appeared in foreign countries in the late 1970s and were applied to gas transportation equipment on offshore platforms. They were originally used to solve the problem of shaft end sealing of high-speed centrifugal compressors. Unlike liquid lubricated mechanical seals, dry gas seals produce a gas film with stable rigidity on the two sealing surfaces, so that the two sealing end faces are completely separated and a certain sealing gap is maintained, but it is only suitable for fluid media without impurities. The above three types of sealing rubber seals, packing seals, and dry gas seals are not related to the present invention. The first two types have been gradually eliminated due to large friction and worn shafts, and are only suitable for occasions where mechanical seals cannot be used. The latter type is limited by the cleanliness of the medium and the cost, and has limited use. The present invention is generally classified into a contact type mechanical seal, which is currently the most common sealing device for pump rotating equipment in the world and is used to isolate the fluid in the pump body from the air outside the pump.

[0003] In contact-type mechanical seals for pumps, although there are many common sealing ring designs, there are rules in the design of sealing rings. The common point is that the dynamic and static sealing rings are flush on the side in contact with the liquid, that is, the diameters are the same. The reason is to prevent impurities in the liquid from accumulating, colliding, and entering the sealing surface at the contact point; the side in contact with the air is often not flush because there is no problem of impurities. Therefore, in order to reduce friction, a design with one narrow ring and one wide ring is adopted; the above is a reasonable design that conforms to fluid mechanics and thermodynamics. On the contrary, if the end of the sealing ring that contacts the liquid is not flush with the mechanical seal, it is often a special case. Due to the special working conditions of different medium fluid sealing, they are roughly listed as follows: For example, in Chinese patent CN107355416A, Japanese patent JP2-80864A and US patent US9683451B1, although one ring of the dynamic and static sealing ring that contacts the liquid is higher than the other ring, the raised part is upright, which is easy to cause the accumulation of impurity particles and enter the sealing surface. It is a special form of sealing for special working conditions; for example, in Chinese patent CN205534228U, CN204692584U and US patent US9841108B2, although one ring of the dynamic and static sealing ring that contacts the liquid is higher than the other ring, the part of the high ring above the contact surface is not only not inclined, but also the narrow ring is inclined, and the V-shaped angle formed is more likely to cause the accumulation of impurities in the liquid. It is also a special form of sealing for special working conditions; for example, in Chinese patents CN206338413U, CN207178077U and Japanese patents JP2005-113983A and JP2007-139140A, although one ring of the dynamic and static sealing rings in contact with the liquid is higher than the other ring, the wide ring part is higher and tilted backward, and cannot block the large impurity particles in the liquid from entering the sealing surface, which is also a special form of sealing for special working conditions. These special sealing forms for special working conditions are based on different considerations, and their common feature is that they are not suitable for media in fluids, because they do not solve the problem of impurity accumulation, collision, and entry into the sealing contact surface caused by the unevenness of the two rings on the side in contact with the liquid. If used in general liquids, impurity particles entering the friction sealing surface will cause abrasive wear between the sealing end faces, resulting in early failure of the seal. Because of this, in contact mechanical seals for pumps that may carry impurity particles, flush sealing surfaces on the liquid side are still the most common design form. Summary of the invention

[0004] In order to solve the technical deficiencies of existing mechanical seals for liquids, the present invention provides a mechanical seal for liquids with a forward-inclined peripheral edge that can effectively keep solid impurities in the liquid away from the sealing end face, thereby reducing the possibility of impurities accumulating, colliding, and entering the sealing surface. The sealing ring is provided with a highly protruding peripheral edge facing the side where the liquid is located. Due to the relative movement of the liquid, turbulence occurs on the protruding inclined surface of the peripheral edge. Non-liquid impurities are discharged along the inclined surface or away from the sealing end face due to the centrifugal force, effectively preventing non-liquid substances from entering and damaging the friction sealing ring surface. The increase in the protruding peripheral edge improves the strength of the sealing ring body, expands the heat dissipation area of ​​the ring body, reduces the deformation of the sealing surface due to friction and heat, and significantly improves the liquid sealing effect and service life. It is a more ideal mechanical seal for liquids.

[0005] To achieve the above objectives, the present invention adopts the following innovative designs and technical solutions:

[0006] A mechanical seal for liquid with an outer edge includes a dynamic ring and a static ring. A spring or a bellows is provided along the axis of the dynamic ring or the static ring. The elastic force makes the end faces of the dynamic ring and the static ring fit together and makes the end faces perpendicular to the axis. One side of the contact surface of the dynamic ring and the static ring is air, and the other side is liquid. The dynamic ring and the static ring fit tightly to prevent the liquid from leaking from one side to the other. It is characterized in that the cross-sectional widths of the dynamic ring and the static ring are different, so that the end portions of the dynamic ring and the static ring fit together. On the liquid side of the dynamic ring and the static ring, the ring with a larger cross-sectional width is provided with a radially highly protruding peripheral edge, while the ring with a narrower cross-sectional width is parallel to the axis and has no protrusion near the liquid side, and the peripheral edge is tilted forward to the side of the ring with a narrower cross-sectional width.

[0007] As an optimization solution of the present invention, the aforementioned liquid mechanical seal having an outer peripheral edge is only arranged on the outer side of the contact surface between the dynamic ring and the static ring.

[0008] As an optimization solution of the present invention, the aforementioned liquid mechanical seal having an outer peripheral edge is only arranged on the inner side of the contact surface between the dynamic ring and the static ring.

[0009] As an optimization solution of the present invention, the aforementioned liquid mechanical seal with a peripheral edge has a moving ring of an integral or split structure; and a stationary ring of an integral or split structure.

[0010] As an optimization solution of the present invention, the connection between the forward inclined portion of the peripheral edge of the aforementioned liquid mechanical seal and the fitting surfaces of the dynamic ring and the static ring is an arc inclination, an oblique line inclination or a right angle.

[0011] As an optimization solution of the present invention, the aforementioned liquid with an outer edge is mechanically sealed, and the connection point between the outer edge and the fitting surface intersects with the forward tilt point of the outer edge or the distance is greater than zero.

[0012] As an optimization solution of the present invention, the aforementioned liquid with an outer peripheral edge is mechanically sealed, and the inclined surface of the peripheral edge is provided with a protrusion.

[0013] As an optimization solution of the present invention, the aforementioned liquid mechanical seal with an outer edge has a cross-section of a cone, trapezoid, polygon, arc or any combination of cone, trapezoid, polygon and arc.

[0014] As an optimization solution of the present invention, the aforementioned liquid mechanical seal with an outer edge, the material of the dynamic ring and the static ring is any one of plastic, ceramic, graphite, and metal alloy.

[0015] The beneficial effects achieved by the present invention are:

[0016] (1) When the moving ring rotates, the liquid is driven to rotate through the surrounding edge, so that the solid impurities in the liquid are kept away from the contact surface between the moving ring and the static ring, thus preventing the impurities from accumulating at the contact point between the sealing ring contact surface and the medium.

[0017] (2) The surrounding edge can be set on the inner or outer side of the contact surface between the dynamic ring and the static ring. The two structures have their own characteristics and can meet a variety of usage scenarios.

[0018] (3) The surrounding edge blocks large solid impurities in the liquid, preventing the impurities from accumulating at the contact point between the sealing ring contact surface and the medium.

[0019] (4) The surrounding edge expands the heat dissipation area of ​​the ring and reduces thermal deformation.

[0020] (5) The surrounding edge can appropriately reduce the friction of the sealing surface and extend the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 An axial cross-sectional view of the first embodiment of the present invention in a mechanical seal application;

[0022] Figure 2 Axial cross-sectional view of the sealing ring structure with a relatively large and narrow cross-sectional width according to the first embodiment of the present invention;

[0023] Figure 3 A diagram showing a structure with a larger cross-sectional width according to the first embodiment of the present invention;

[0024] Figure 4 Axial cross-sectional view of the second embodiment of the present invention with a larger cross-sectional width;

[0025] Figure 5 Axial cross-sectional view of the third embodiment of the present invention with a larger cross-sectional width;

[0026] Figure 6 Axial cross-sectional view of the fourth embodiment of the present invention with a larger cross-sectional width;

[0027] Figure 7Axial cross-sectional view of the fifth embodiment of the present invention with a larger cross-sectional width;

[0028] Figure 8 Axial cross-sectional view of the sixth embodiment of the present invention with a larger cross-sectional width;

[0029] Fig. 9 Axial cross-sectional view of the seventh embodiment of the present invention with a larger cross-sectional width;

[0030] Fig.10 Axial cross-sectional view of the eighth embodiment of the present invention with a larger cross-sectional width;

[0031] Fig.11 An axial cross-sectional view of the eighth embodiment of the present invention in the application of a cartridge mechanical seal;

[0032] Description of the numbers in the figure:

[0033] 1-dynamic ring, 2-static ring, 3-shaft, 4-pressure cover, 5-surrounding edge, 6-housing, 7-spring, 8-dynamic ring sealing end face, 9-static ring sealing end face, 10-shaft sleeve, 11-locking ring, 51-inclined connecting line one, 52-inclined connecting line two, 53-inclined connecting line three, 54-inclined connecting line four, 55-inclined connecting line five, 56-inclined connecting line six, 57-inclined connecting line seven, 58-right-angle connecting line eight. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example

[0035] like Figure 1 , Figure 2 and Figure 3 As shown: This embodiment discloses a mechanical seal for liquid with an outer edge, including a dynamic ring and a static ring, wherein the dynamic ring 1 or the static ring 2 is provided with a spring 7 or a bellows along the axial direction, so that the sealing end face of the dynamic ring 1 or the static ring 2 is tightly fitted and perpendicular to the shaft 3; the dynamic ring 1, the spring or the bellows are connected and fixed to the shaft 3, the static ring 2, the pressure cover 4 are connected and fixed to the housing 6, and the shaft 3 and the housing 6 rotate relative to each other to prevent the liquid on one side of the sealing end face from leaking to the side close to the shaft 3. The width of the dynamic ring 1 is greater than the width of the static ring 2. The so-called width of the ring refers to 1 / 2 of the difference between the outer diameter and the inner diameter of the cross-section of the two rings. Due to the different widths of the two rings, the static ring sealing end face 9 and the dynamic ring sealing end face 8 are not completely fitted; on the liquid side of the sealing surface, the dynamic ring 1 is provided with a peripheral edge 5, and the static ring 2 with a smaller diameter has no protrusion (hollow cylindrical structure); the peripheral edge 5 partially protrudes along the axial direction of the dynamic ring 1 or the static ring 2 and is provided with an inclined surface, and the inclination angle of the inclined surface ( Figure 2 a) is greater than 10°.

[0036] The dynamic ring 1 is of integral or split structure; the static ring 2 is of integral or split structure. The integral structure means that the dynamic ring 1 or the static ring 2 is a whole and cannot be split; the split structure means that the dynamic ring 1 or the static ring 2 is splittable and is composed of multiple different parts.

[0037] That is, the difference between the inner diameter of the rim and the outer diameter of the ring with a narrower width is greater than or equal to zero, and the end of the sealing ring with a narrower width does not contact the rim.

[0038] The surrounding edge 5 of this embodiment is inclined forward on the outside of the dynamic ring sealing end face 8, and the inclined connecting line 51 between the inclined part and the vertical line of the sealing surface 8 is an oblique line, and the inclined part of the surrounding edge 5 starts from the end point of the contact surface of the static ring sealing end face 9. The surface roughness of the contact part between the dynamic ring sealing end face 8 and the static ring sealing end face 9 is less than 0.6 microns, and the convex surface of the surrounding edge 5 (the upper end of the surrounding edge) is greater than 0.6 microns; the material of the dynamic ring 1 and the static ring 2 is preferably any one of plastic, ceramic, graphite, and metal alloy.

[0039] During operation, the liquid and the peripheral edge 5 are on the same side. When the two sealing rings rotate relative to each other, the peripheral edge 5 drives the surrounding liquid to move relative to each other through the adhesion between itself and the liquid, causing turbulence on the convex inclined surface of the peripheral edge 5. Since the density of most non-liquid particles is greater than that of the liquid, non-liquid impurities are discharged along the inclined surface or away from the above-mentioned sealing end surface under the action of centrifugal force, thereby preventing impurities from accumulating at the contact point between the sealing ring contact surface and the medium. At the same time, it blocks large solid impurities in the liquid, effectively preventing non-liquid substances from entering and damaging the friction sealing ring surface. The peripheral edge 5 improves the ring body strength of the sealing ring, expands the heat dissipation area of ​​the ring body, reduces the friction heat deformation of the sealing surface, improves the liquid sealing effect and extends the service life. Example

[0040] like Figure 4 As shown: The difference between this embodiment and the first embodiment is that: in this embodiment, the liquid is on the inner side of the contact surface between the dynamic ring 1 and the static ring 2, and the surrounding edge 5 protrudes on the inner side of the dynamic ring sealing end surface 8, and the protrusion is inclined forward at an angle of ( Figure 4 a) is greater than 10°, the inclined connecting line 52 between the inclined portion and the dynamic ring sealing end face 8 is an oblique line, and the cross-section of the surrounding edge 5 is a trapezoid.

[0041] When the peripheral edge 5 rotates, the peripheral edge 5 mainly drives the surrounding liquid to rotate through the adhesion between itself and the surrounding liquid. When the non-liquid particle flow approaches the peripheral edge 5, the peripheral edge 5 drives the non-liquid particles in the liquid to rotate. When the rotation speed of the non-liquid particles is high, turbulence will be formed in the liquid. The non-liquid particles that form turbulence will easily move to the center of the pipeline. The liquid flow rate in the center of the pipeline is relatively fast, which can accelerate the non-liquid particles to move away from the friction pair as soon as possible to a certain extent and avoid entering the interior of the friction pair. Extend the service life of the mechanical seal of this embodiment. Example

[0042] like Figure 5 As shown: The difference between this embodiment and embodiment 1 is that the surrounding edge 5 of this embodiment is inclined forward and protrudes to be connected to the sealing end face and the outer circumferential surface of the ring, the inclined connecting line 53 between the inclined part and the vertical line of the sealing surface is an oblique line, the connecting surface with the outer circumferential surface is an arc surface, and the cross-section of the surrounding edge 5 is a combination of a cone and an arc. Example

[0043] like Figure 6 As shown: The difference from the first embodiment is that in this embodiment, the surrounding edge 5 is protruded forward and connected to the dynamic ring sealing end face 8 and the outer circumferential surface of the ring, the inclined connecting line 54 between the inclined part and the vertical line of the dynamic ring sealing end face 8 is an arc connecting an oblique line, the connecting surface with the outer circumferential surface is an inclined surface, and the cross-section of the protruding part of the surrounding edge 5 is a combination of a polygon and an arc. Example

[0044] like Figure 7 As shown: The difference from the first embodiment is that the surrounding edge 5 of this embodiment is connected to the dynamic ring sealing end face 8 and the outer circumference of the dynamic ring 1 by a forward tilting protrusion, and the inclined connecting line 55 between the inclined part and the vertical line of the dynamic ring sealing end face 8 is an arc connecting an oblique line, and the connecting surface with the outer circumference of the dynamic ring 1 is a vertical surface. The cross section of the forward tilting protrusion of the surrounding edge 5 is a combination of a trapezoid and an arc.

[0045] The difference between Example 3 to Example 5 and Example 1 is that the diameter of the surrounding edge 5 of Example 3 to Example 5 is larger than the diameter of the dynamic ring 1, which determines that compared with Example 1, under the same angular velocity, the linear velocity of the surrounding edge 5 of this embodiment is higher and the contact area with the external liquid is larger, so the driving effect on the external liquid is better and the effect of removing non-liquid particles is better. Example

[0046] like Figure 8 As shown: the difference from the first embodiment is that in this embodiment, the surrounding edge 5 protrudes forward and tilts on the outer periphery of the dynamic ring sealing end face 8, the inclined connecting line 6 56 between the inclined part and the vertical line of the dynamic ring sealing end face 8 is an arc line, and the cross-section of the forward-tilted protruding part of the surrounding edge 5 is an arc. Example

[0047] like Fig. 9 As shown: the difference from the first embodiment is that the peripheral edge 5 of this embodiment protrudes forward and tilts on the outer periphery of the dynamic ring sealing end face 8, the inclined connection seven 57 between the inclined portion and the vertical line of the dynamic ring sealing end face 8, the surface roughness of the protruding inclined surface is greater than 1 mm, and the cross-section of the forward tilted protruding portion of the peripheral edge 5 is a combination of a cone and a polygon.

[0048] The difference between Example 6 and Example 7 and Example 1 is that the inclined connecting line 6 56 and the inclined connecting line 7 57 of the surrounding edge 5 in Example 6 and Example 7 are not straight lines, but are provided with protrusions, and the protrusions are arc-shaped or sawtooth-shaped, which can increase the contact area between the surrounding edge 5 and the liquid, effectively improve the rotation speed of the liquid, and enhance the driving effect of the surrounding edge 5 on non-liquid particles. Example

[0049] like Fig.10 and Fig.11 As shown: The difference between this embodiment and embodiment 1 is that: this embodiment discloses a mechanical seal for liquid with an outer edge, which is implemented in the application of a containerized mechanical seal, including a dynamic ring 1 and a static ring 2, wherein the dynamic ring 1 or the static ring 2 is provided with a spring 7 or a bellows along the axial direction, so that the sealing end face of the dynamic ring 1 or the static ring 2 is tightly fitted and perpendicular to the shaft 3; the dynamic ring 1, the spring 7 or the bellows is installed on the sleeve 10, which is connected and fixed to the shaft 3 by a locking ring 11, the static ring 2, the pressure cover 4 are connected and fixed to the housing 6, and the shaft 3 and the housing 6 rotate relative to each other, thereby isolating the liquid on one side of the sealing end face from leaking to the side close to the sleeve 3. The cross-sectional width of the dynamic ring 1 is greater than that of the static ring 2, so that the sealing end face of the dynamic ring 1 is partially fitted with the sealing end face of the static ring 2; on the liquid side of the sealing surface, the dynamic ring 1 with a larger cross-sectional width is provided with a radially highly protruding edge 5, while the static ring 2 with a narrower cross-sectional width is close to the liquid side and is parallel to the axis without protrusions, and the edge 5 is tilted forward toward the static ring 2 with a narrower cross-sectional width, and the connection between the forward tilted part and the fitting surface of the dynamic ring 1 and the static ring 2 is at a right angle; the distance between the connection point of the edge 5 and the fitting surface and the forward tilted point of the edge 5 is greater than zero.

[0050] The peripheral edge 5 of the dynamic ring 1 of this embodiment protrudes forward and tilts at the outer periphery of the dynamic ring sealing end face 8, and the forward tilted portion (the inner side of the peripheral edge 5) forms a right angle with the dynamic ring sealing end face 8, and the right angle connecting line 8 58 is a straight line perpendicular to the dynamic ring sealing end face 8, and the cross section of the peripheral edge 5 is a trapezoid. In addition to the advantages described in the first embodiment, the peripheral edge 5 of this embodiment can block large or heavy particle impurities in the liquid from accumulating at the contact point between the sealing ring contact surface and the medium, and at the same time has a driving effect on the external liquid to exclude lighter non-liquid particles.

[0051] The above-mentioned multiple embodiments are only preferred implementation modes of the present invention for liquid diversity, particulate impurity diversity and different content of particulate impurity. It should be pointed out that for technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A mechanical seal for liquid with an outer edge, including a dynamic ring and a static ring, wherein a spring or a bellows is provided along the axis of the dynamic ring or the static ring, and the elastic force makes the end faces of the dynamic ring and the static ring fit together and make the end faces perpendicular to the axis; one side of the contact surface of the dynamic ring and the static ring is air, and the other side is liquid, and the sealing end faces of the dynamic ring and the static ring fit closely together to prevent liquid from leaking from one side to the other, characterized in that: The dynamic ring and the static ring have different cross-sectional widths, so that a part of the dynamic ring sealing end face fits with the end part of the static ring sealing end face; on the liquid side of the dynamic ring and the static ring, the dynamic ring with a larger cross-sectional width is provided with a radially highly protruding rim, while the static ring with a narrower cross-sectional width is close to the liquid side and parallel to the axis without protrusions, and the rim is inclined forward toward the side of the static ring with a narrower cross-sectional width and is provided with an inclined portion, and the inclined portion starts from the end point of the contact surface of the static ring sealing end face.

2. The liquid mechanical seal with a peripheral edge according to claim 1, characterized in that: The surrounding edge is only arranged on the outer side of the contact surface between the moving ring and the stationary ring.

3. The liquid mechanical seal with a peripheral edge according to claim 1, characterized in that: The surrounding edge is only arranged on the inner side of the contact surface between the moving ring and the stationary ring.

4. The liquid mechanical seal with a peripheral edge according to claim 1, characterized in that: The dynamic ring is an integral or split structure; the static ring is an integral or split structure.

5. The liquid mechanical seal with a peripheral edge according to any one of claims 1 to 4, characterized in that: The connection between the forward inclined portion of the peripheral edge and the fitting surfaces of the dynamic ring and the static ring is in the form of an arc inclination, an oblique line inclination or a right angle.

6. The liquid mechanical seal with a peripheral edge according to any one of claims 1 to 3, characterized in that: The connection point between the peripheral edge and the fitting surface intersects with the forward tilt point of the peripheral edge or the distance therebetween is greater than zero.

7. The liquid mechanical seal with a peripheral edge according to any one of claims 1 to 3, characterized in that: The inclined surface of the peripheral edge is provided with a protrusion.

8. The liquid mechanical seal with a peripheral edge according to any one of claims 1 to 3, characterized in that: The cross section of the peripheral edge is conical, trapezoidal, polygonal, arc-shaped or any combination of conical, trapezoidal, polygonal and arc-shaped.

9. The liquid mechanical seal with a peripheral edge according to any one of claims 1 to 3, characterized in that: The material of the dynamic ring and the static ring is any one of plastic, ceramic, graphite and metal alloy.

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