A device and method for removing residual aluminum liquid on a ring after aluminizing

Abstract

The present invention discloses a device and method for removing residual aluminum liquid on a ring after aluminizing, comprising a scraper, the scraper extending from its middle position to both sides along a first direction to form a curved scraper, including an inner arc surface and an outer arc surface; a second direction perpendicular to the first direction within the inner arc surface and the outer arc surface of the scraper is a straight line direction, and the angle between the second direction and the ground on one side of the outer arc surface is an acute angle; the scraper has a first arc edge for scraping liquid, and all points on the first arc edge are on the same horizontal plane; and also includes a base, the upper end of which is connected to the outer arc surface. Without increasing the redundant movements of the robot arm, the rapid removal of residual aluminum liquid on the ring after passing through the aluminum bath is achieved, so that the ring after aluminizing can be directly sent to the mold closing process, and the residual aluminum liquid is recycled, avoiding waste and pollution of the working environment; it has a self-positioning function and can be quickly arranged under different working environments.

Description

Technical Field

[0001] The invention relates to the technical field of internal combustion engines, in particular to a device and a method for removing residual aluminum liquid on a ring after aluminum infiltration. Background Art

[0002] In order to improve the wear resistance of aluminum pistons in internal combustion engines, the process of inserting wear-resistant rings in piston ring grooves is currently widely used. The insert rings are generally inserted in the ring grooves of the piston head. Piston insert rings can increase the power of internal combustion engines sharply. When the piston working conditions are harsh, the combustion chamber can maintain a reliable seal to avoid gas and oil blowby, as well as cylinder pulling and cylinder biting, and reduce the lubricating oil and fuel consumption of the internal combustion engine and the emission of exhaust gas.

[0003] In order to enhance the wear resistance of the insert ring, the insert ring is generally made of cast iron. In order to firmly combine the cast iron insert ring with the aluminum piston, the insert ring needs to be aluminized before being cast into the aluminum piston to ensure that the surface of the insert ring is evenly aluminized. At present, aluminum bath aluminization is generally used, that is, after the surface of the insert ring is cleaned, it is hung on a molybdenum wire hook and immersed in aluminum alloy liquid heated to a certain temperature for aluminization, and then lifted out of the furnace, and the insert ring is clamped by a mechanical arm to the next process for mold closing.

[0004] The uniformity of the aluminizing layer will directly affect the connection strength between the insert and the piston, and therefore directly affect the life of the engine. However, when the insert is taken out of the aluminizing bath, it will carry residual aluminum liquid, causing aluminum accumulation, and the time from the insert being taken out of the aluminizing furnace to being covered by aluminum liquid should be controlled as short as possible. Therefore, it is very necessary to develop a device and method that can quickly remove the residual aluminum liquid on the insert after aluminizing. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for removing residual aluminum liquid on the insert ring after aluminizing, so as to solve the problem mentioned in the above background technology that the insert ring will carry residual aluminum liquid when it is out of the aluminum bath, causing aluminum accumulation.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention discloses a device for removing residual aluminum liquid on a ring after aluminizing, comprising:

[0008] A scraper, the scraper extends from its middle position to both sides along a first direction to form a curved scraper, including an inner curved surface and an outer curved surface; a second direction perpendicular to the first direction within the inner curved surface and the outer curved surface of the scraper is a straight line direction, and an angle between the second direction and the ground on one side of the outer curved surface is an acute angle; the scraper has a first curved edge for scraping liquid, and all points on the first curved edge are on the same horizontal plane;

[0009] A base, wherein the upper end of the base is connected to the outer arc surface.

[0010] As a further solution of the present invention: the base includes a bottom plate and a support rod, one end of the support rod is connected to the outer arc surface, and the other end is connected to the bottom plate.

[0011] As a further solution of the present invention: the scraper has a fan-shaped plate structure, and the curved scraper also has a second arc edge opposite to the first arc edge, the plane where the first arc edge is located is parallel to the plane where the second arc edge is located, and the first arc edge is located above the second arc edge.

[0012] As a further solution of the present invention: the curved scraper is formed by a plurality of slats spliced ​​in parallel and fixed by an elastic clamp, the length direction of the slats is consistent with the second direction, the width direction of the slats is tangent to the first direction, and the direction of the elastic clamp is consistent with the first direction.

[0013] As a further solution of the present invention: the support rod is made of plastic material.

[0014] As a further solution of the present invention: the support rod is made of a rigid material.

[0015] As a further solution of the present invention: the distance between the two end points of the first arc edge is larger than the outer diameter of the insert ring.

[0016] As a further solution of the present invention: a recovery bucket for collecting aluminum liquid is placed under the curved scraper.

[0017] As a further solution of the present invention: the inner arc surface has an inner surface layer of corrosion-resistant and high-temperature-resistant material.

[0018] Another aspect of the present invention discloses a method for removing residual aluminum liquid from a ring after aluminizing as described above, comprising the following steps:

[0019] S1: The robot arm grabs the inlay ring that has not been aluminum bathed, and adjusts the height of the base so that the first arc edge of the scraper is 5-10mm higher than the bottom end surface of the inlay ring;

[0020] S2: The driving mechanical arm drives the insert ring to move horizontally from the inner arc surface to the outer arc surface, so that the insert ring slightly collides with the first arc edge, completing the self-positioning of the scraper;

[0021] S3: The robot arm returns to its original position, grabs the inlay ring that has passed through the aluminum bath, and moves it horizontally along the inner arc surface toward the outer arc surface. The residual aluminum liquid on the inlay ring flows downward along the inner arc surface and flows into the recovery bucket.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: without adding unnecessary movements of the robot arm, the residual aluminum liquid on the insert ring that has passed through the aluminum bath can be quickly removed, so that the insert ring after aluminum infiltration can be directly sent to the mold closing process, and the residual aluminum liquid can be recycled, avoiding waste and pollution of the working environment; the support rod and elastic clamp made of plastic material can realize self-positioning of the scraper in the height direction, and can be quickly arranged under different working environments; and can prevent the insert ring and the scraper from being damaged in the event of an accidental collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the working state of the present invention in Example 1;

[0024] Figure 2 This is a schematic diagram of the working state of the present invention in Example 2;

[0025] Figure 3 It is a schematic diagram of the structure of the scraper in Example 2 of the present invention;

[0026] Figure 4 It is a top view of the present invention in Example 2;

[0027] In the figure: 1-scraper, 11-inner arc surface, 12-outer arc surface, 13-first arc edge, 14-second arc edge, 15-slat, 2-base, 21-bottom plate, 22-support rod, 3-elastic clamp, 4-recovery barrel, 5-inlaid ring, 6-mechanical arm. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 , Figure 3In Example 1, a device for removing residual aluminum liquid on a ring after aluminum infiltration includes a scraper 1 and a base 2. The scraper 1 extends from its middle position to both sides along a first direction to form a curved scraper, including an inner arc surface 11 and an outer arc surface 12; the second direction perpendicular to the first direction in the surface of the inner arc surface 11 and the outer arc surface 12 of the scraper 1 is a straight line direction; the first direction along the inner and outer arc surfaces is a curve; technicians in this field know that in the surface of the inner and outer arc surfaces, when the first direction is perpendicular to the second direction and the second direction is a straight line and the first direction is a curve, the first direction and the second direction are the only determined directions. The angle between the second direction and the ground on one side of the outer arc surface 12 is an acute angle of 60-80°; the scraper 1 has a first arc edge 13 for scraping liquid, and all points on the first arc edge 13 are on the same horizontal plane; the base 2 includes a bottom plate 21 and a support rod 22, one end of the support rod 22 is connected to the outer arc surface 12, and the other end is connected to the bottom plate 21.

[0030] Please continue reading Figure 3 The scraper 1 has a fan-shaped plate structure, and the curved scraper also has a second arc edge 14 opposite to the first arc edge 13. The plane where the first arc edge 13 is located is parallel to the plane where the second arc edge 14 is located, and the first arc edge 13 is located above the second arc edge 14.

[0031] Furthermore, the support rod 22 is made of plastic material and can undergo large plastic deformation without rebound or structural damage after being hit by external force at room temperature. This is a prior art and is described in detail in the patent documents with publication numbers CN102382476B and CN109206703A. As an alternative, the support rod 22 can also adopt a universal tube, which is often used on table lamp supports. This is a prior art and will not be elaborated here.

[0032] Furthermore, the distance between the two ends of the first arc edge 13 is larger than the outer diameter of the insert ring 5, and the plane where the first arc edge 13 is located is parallel to the insert ring 5, so that the scraper 1 can scrape away the residual aluminum liquid on the bottom end surface of the insert ring 5 at one time. In addition, the surface of the inner arc surface 11 is made of corrosion-resistant and high-temperature resistant material, such as enamel or ceramic. A recovery bucket 4 for collecting aluminum liquid is placed under the curved scraper.

[0033] In this embodiment 1, a method for removing residual aluminum liquid from a ring after aluminizing comprises the following steps:

[0034] S1: The inner claw of the robot arm 6 grabs the inlay ring 5 that has not been aluminum bathed, and adjusts the height of the base 2 so that the first arc edge 13 of the scraper 1 is 5-10 mm higher than the bottom end surface of the inlay ring 5;

[0035] S2: driving the mechanical arm 6 to drive the insert ring 5 to move horizontally along the direction from the inner arc surface 11 to the outer arc surface 12 at a speed of 0.5-1 cm / s; causing the insert ring 5 to slightly collide with the first arc edge 13 to complete the self-positioning of the scraper 1;

[0036] S3: the robot arm 6 returns to its original position, and its inner claw grabs the inlay ring 5 that has passed through the aluminum bath, and makes it move horizontally along the inner arc surface 11 toward the outer arc surface 12, and the residual aluminum liquid on the inlay ring 5 flows downward along the inner arc surface 11 and flows into the recovery barrel 4.

[0037] It should be noted that in step S2, the support rod 22 of the plastic material undergoes plastic deformation under the slow collision of the bezel 5, so that the position of the scraper 1 is displaced downward and backward. During the slow contact between the bezel 5 and the first arc edge 13, the height of the first arc edge 13 becomes approximately the same as the height of the bottom end face of the bezel 5, and the two are in contact with each other with a spacing of 0-2mm, and the plane where the first arc edge 13 is located is kept parallel to the bottom end face of the bezel 5, completing the self-positioning of the scraper 1. In step S1, there is no particular limitation on the method of adjusting the height of the base 2, which can be achieved by placing a pad at the bottom thereof.

[0038] See also Figure 2 , Figure 4 In Embodiment 2 of the present invention, a device for removing residual aluminum liquid on a ring after aluminum infiltration comprises a scraper 1 and a base 2. The scraper 1 extends from its middle position to both sides along a first direction to form a curved scraper, including an inner arc surface 11 and an outer arc surface 12; the second direction perpendicular to the first direction in the surface of the inner arc surface 11 and the outer arc surface 12 of the scraper 1 is a straight line direction; the first direction along the inner and outer arc surfaces is a curve; those skilled in the art know that in the surface of the inner and outer arc surfaces, when the first direction is perpendicular to the second direction and the second direction is a straight line and the first direction is a curve, the first direction and the second direction are the only determined directions. The angle between the second direction and the ground on one side of the outer arc surface 12 is an acute angle of 60-80°; the scraper 1 has a first arc edge 13 for scraping liquid, and all points on the first arc edge 13 are on the same horizontal plane; the base 2 comprises a bottom plate 21 and a support rod 22, one end of the support rod 22 is connected to the outer arc surface 12, and the other end is connected to the bottom plate 21.

[0039] Please continue reading Figure 4The curved scraper is formed by a plurality of slats 15 spliced ​​in parallel and fixed transversely by two upper and lower parallel elastic clamps 3. The length direction of the slats 15 is consistent with the second direction, the width direction of the slats 15 is tangent to the first direction, and the length direction of the elastic clamps 3 is consistent with the first direction; the support rod 22 is a rigid material, such as iron, steel, etc. When the scraper 1 is subjected to a low-speed collision, the elastic clamping force of the upper and lower elastic clamps 3 on the scraper 1 is in the horizontal direction, the lateral displacement of the slats 15 has been limited, and the support rod 22 is rigid, the slats 15 are forced to shrink downward along the second direction, so that the scraper 1 abuts against the inlay ring 5, and the distance between the two is 0-2mm, completing the self-positioning of the scraper 1.

[0040] In this embodiment 2, a method for removing residual aluminum liquid from a ring after aluminizing is provided, comprising the following steps:

[0041] S1: The inner claw of the mechanical arm 6 grabs the inlay ring 5 that has not been aluminum bathed, and adjusts the height of the base 2 so that the first arc edge 13 of the scraper 1 is 5-10 mm higher than the bottom end surface of the inlay ring 5;

[0042] S2: driving the mechanical arm 6 to drive the ring 5 to move horizontally along the direction from the inner arc surface 11 to the outer arc surface 12 at a speed of 0.5-1 cm / s, so that the ring 5 slightly collides with the first arc edge 13, completing the self-positioning of the scraper 1;

[0043] S3: the robot arm 6 returns to its original position, and its inner claw grabs the inlay ring 5 that has passed through the aluminum bath, and makes it move horizontally along the inner arc surface 11 toward the outer arc surface 12, and the residual aluminum liquid on the inlay ring 5 flows downward along the inner arc surface 11 and flows into the recovery barrel 4.

[0044] In other embodiments, Figure 1 As shown, aluminum liquid remains on the insert ring 5 after passing through the aluminum bath, and the robot arm 6 clamps the insert ring 5 through the inner clamping claw and sends it to the next mold closing process. On the path where the robot arm 6 clamps the insert ring 5 through the inner clamping claw and sends it to the next process, a cleaning device for cleaning the residual aluminum liquid is provided. The cleaning device includes a scraper 1 provided on a support rod 22 made of plastic material, and a recovery bucket 4 provided below the scraper 1. Figure 3 As shown, the scraper 1 has a first arc edge 13 and a funnel-shaped inner arc surface 11. The arc length of the first arc edge 13 is greater than the diameter of the insert ring 5. The surfaces of the first arc edge 13 and the funnel-shaped inner arc surface 11 are both ceramic layers that are resistant to high temperature and corrosion of the aluminum liquid, such as enamel. The first arc edge 13 is set at a distance of 0-2mm from the lower surface of the insert ring 5 passing through. In this way, when the insert ring 5 passes through the scraper 1, the aluminum liquid remaining on the lower surface of the insert ring 5 will be scraped off by the first arc edge 13. The scraped aluminum liquid flows into the recovery bucket 4 set below the scraper 1 through the funnel-shaped inner arc surface 1110 of the scraper 1 and is recovered.

[0045] In this embodiment, if an unexpected situation occurs, such as a parameter setting error, which causes the movement trajectory of the robot arm 6 to deviate, causing the height of the ring 5 to be lower than the first arc edge 13, so that when the ring 5 and the scraper 1 collide, since the scraper 1 is set on the support rod 22 of plastic material, the scraper 1 will deflect after being subjected to force, thereby avoiding damage to the ring 5 and the scraper 1.

[0046] In another embodiment, if Figure 4 As shown, the scraper 1 is set on a support rod 22 made of a rigid material and fixed by an upper and lower parallel elastic clamp 3. At this time, when the inlay ring 5 and the scraper 1 collide, since the inner arc surface 11 of the scraper 1 is inclined and the support rod 22 is rigid, the elastic clamp 3 exerts an elastic clamping force on the scraper 1 in the horizontal direction, and the scraper 1 will shrink downward along the elastic clamp 3 under the horizontal force of the inlay ring 5, thereby avoiding damage.

[0047] Furthermore, the height difference of the scraper 1 relative to the lower surface of the insert ring 5 needs to be precisely set: if the scraper 1 is set too low, the residual aluminum liquid on the lower surface of the insert ring 5 may not be scraped off, or it may not be completely removed; if the scraper 1 is set too high, it may collide with the moving insert ring 5. However, due to the limitations of various workstations and working conditions at the production site, it is not convenient and easy to achieve such a precise setting, and once the set running route of the robot arm 6 changes, it must be reset. In this embodiment, the scraper 1 can be set in the following way: first, the scraper 1 is set slightly higher than the moving track of the insert ring 5, for example, 5-10mm, and the robot arm 6 carries the insert ring 5 that has not been aluminum bathed or is useless through the scraper 1 at a slower speed. Through a slight collision, the scraper 1 will move downward to the right position. At this time, the position of the scraper 1 on the elastic clamp 3 can just remove the aluminum liquid on the insert ring 5 without collision, and then normal operation can be performed. That is to say, through a controlled collision, the "self-positioning" of the scraper 1 can be achieved simply and quickly.

[0048] In a further embodiment, a plurality of parallel groove-type flow channels or corrugated flow channels may be provided on the funnel-shaped inner arc surface 11 of the scraper 1 , so that the scraped aluminum liquid can be collected and flow into the recovery barrel 4 through the flow channels to prevent it from cooling and solidifying on the scraper 1 surface.

[0049] In another embodiment, a device for removing residual aluminum liquid on the insert ring after aluminum infiltration is also provided, including a scraper 1, the scraper 1 has a first arc edge 13 and a funnel-shaped inner arc surface 11; the surfaces of the first arc edge 13 and the funnel-shaped inner arc surface 11 are ceramic layers; the arc length of the first arc edge 13 is greater than the diameter of the insert ring; and also includes an aluminum liquid recovery bucket 4 located below the scraper 1.

[0050] Furthermore, the scraper 1 is made of an enamel material.

[0051] Furthermore, the scraper 1 is arranged on a support rod 22 made of plastic material.

[0052] Furthermore, the scraper 1 is arranged on a support rod 22 made of a rigid material through an elastic clamp 3 .

[0053] In some other embodiments, a method for removing residual aluminum liquid on a ring after aluminizing is provided, comprising the following steps:

[0054] The inner clamping claw of the robot arm 6 clamps the insert ring 5 after passing through the aluminum bath, and sends the insert ring 5 horizontally to the next process;

[0055] On the moving path of the insert ring 5, a residual aluminum liquid removal device is arranged, and the residual aluminum liquid removal device comprises a scraper 1, and the scraper 1 has a first arc edge 13 and a funnel-shaped inner arc surface 11; the surfaces of the first arc edge 13 and the funnel-shaped inner arc surface 11 are ceramic layers; the arc length of the first arc edge 13 is greater than the diameter of the insert ring; and also comprises an aluminum liquid recovery bucket 4 located below the scraper 1; the first arc edge 13 is arranged at a distance of 0-2 mm from the lower surface of the insert ring 5 passing by;

[0056] When the insert ring 5 passes through the scraper 1, the aluminum liquid remaining on the lower surface of the insert ring 5 is scraped off by the first arc edge 13;

[0057] The scraped aluminum liquid flows into the aluminum liquid recovery bucket 4 arranged below the scraper 1 through the funnel-shaped inner arc surface 11 of the scraper 1 and is recovered.

[0058] Furthermore, the scraper 1 is made of an enamel material.

[0059] Furthermore, the scraper 1 is arranged on a support rod 22 made of a rigid material.

[0060] Furthermore, the scraper 1 is arranged on a support rod 22 made of a rigid material through an elastic clamp 3 .

[0061] Furthermore, the method also includes the following steps: firstly, the scraper 1 is set slightly higher than the movement trajectory of the insert ring 5, and the robot arm 6 carries the insert ring 5 through the scraper 1 along the set path, so that the scraper 1 shrinks downward along the elastic clamp 3 under the combined action of the horizontal force of the insert ring 5 and its funnel-shaped inner arc surface 11, thereby completing the self-positioning of the scraper 1 in the height setting.

[0062] Furthermore, the scraper 1 is firstly arranged to be 5-10 mm higher than the movement track of the insert ring 5 .

[0063] In particular, in some embodiments, the specially configured scraper 1 can remove the residual aluminum liquid on the insert ring 5 after the aluminum bath without adding unnecessary movements of the robot arm 6, so that the insert ring 5 after aluminum infiltration can be sent to the mold closing process as soon as possible, and the residual aluminum liquid can be recycled to avoid waste and pollution of the working environment. Furthermore, the ceramic layer of the scraper 1 can prevent the high temperature and corrosion of the aluminum liquid, thereby increasing the life of the scraper 1. In addition, the setting of the plastic support rod 22 or the elastic clamp 3 can prevent the insert ring 5 and the scraper from being damaged in the event of an accidental collision. At the same time, the setting of the elastic clamp 3 and the rigid support rod 22 can also realize the self-positioning of the scraper 1 in the height direction, so that the scraper 1 can be quickly arranged in different working environments.

[0064] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0065] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A device for removing residual aluminum liquid on a ring after aluminizing, characterized in that: include: A scraper (1), wherein the scraper (1) extends from its middle position to both sides along a first direction to form a curved scraper, comprising an inner curved surface (11) and an outer curved surface (12); a second direction perpendicular to the first direction within the plane of the inner curved surface (11) and the outer curved surface (12) of the scraper (1) is a straight line direction; an angle between the second direction and the ground on one side of the outer curved surface (12) is an acute angle; the scraper (1) has a first curved edge (13) for scraping liquid, and all points on the first curved edge (13) are on the same horizontal plane; A base (2), the upper end of the base (2) being connected to the outer curved surface (12); The base (2) comprises a bottom plate (21) and a support rod (22), wherein one end of the support rod (22) is connected to the outer arc surface (12), and the other end is connected to the bottom plate (21); The scraper (1) has a fan-shaped plate structure, and the curved scraper also has a second arc edge (14) opposite to the first arc edge (13), the plane where the first arc edge (13) is located is parallel to the plane where the second arc edge (14) is located, and the first arc edge (13) is located above the second arc edge (14).

2. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: The curved scraper is formed by a plurality of slats (15) spliced ​​in parallel and fixed by an elastic clamp (3); the length direction of the slats (15) is consistent with the second direction; the width direction of the slats (15) is tangent to the first direction; and the length direction of the elastic clamp (3) is consistent with the first direction.

3. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: The support rod (22) is made of plastic material.

4. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: The support rod (22) is made of a rigid material.

5. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: The distance between the two end points of the first arc edge (13) is greater than the outer diameter of the insert ring (5).

6. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: A recovery bucket (4) for collecting aluminum liquid is placed below the curved scraper.

7. The device for removing residual aluminum liquid on the insert ring after aluminizing according to claim 1 is characterized in that: The inner arc surface (11) has an inner surface layer made of corrosion-resistant and high-temperature-resistant material.

8. The method for removing residual aluminum liquid from a ring after aluminizing according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: The mechanical arm (6) grabs the inlay ring (5) that has not been exposed to the aluminum bath, and adjusts the height of the base (2) so that the height of the first arc edge (13) of the scraper (1) is 5-10 mm higher than the bottom end surface of the inlay ring (5); S2: driving the mechanical arm (6) to drive the insert ring (5) to move horizontally in a direction from the inner arc surface (11) to the outer arc surface (12), so that the insert ring (5) slightly collides with the first arc edge (13), thereby completing the self-positioning of the scraper (1); S3: The robot arm (6) returns to its original position, grabs the inlay ring (5) that has passed through the aluminum bath, and moves it horizontally along the inner arc surface (11) toward the outer arc surface (12). The residual aluminum liquid on the inlay ring (5) flows downward along the inner arc surface (11) and flows into the recovery bucket (4).

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