A dispersion machine

Abstract

The present invention belongs to the technical field of stirring machinery, and specifically relates to a disperser, comprising a horizontally placed pump body and a driving shaft, wherein one end of the driving shaft is inside the pump body for driving a disperser rotor, and the other end extends outside the pump body and is connected to a power source, wherein the disperser rotor comprises a first rotor and a second rotor, wherein the second rotor is sleeved outside the first rotor and is radially spaced and the two rotors are coaxially arranged; the disperser further comprises a stator fixedly connected to the pump body, wherein the stator is inserted into a gap between the first rotor and the second rotor; a gap formed between the inner circumference and the outer circumference of the stator and the outer circumference of the first rotor and the inner circumference of the second rotor is used for processing materials; a feed port and a discharge port are provided on the pump body, and the disperser rotor and the stator are located in a chamber between the feed port and the discharge port, and the materials are dispersed and ground twice, so that the materials are fully processed, the dispersion effect is good, and the production efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of stirring machinery, and in particular relates to a disperser. Background Art

[0002] Disperser is a kind of mixer in a broad sense. Because it uses a high-speed agitator, it can form a strong tumbling flocculent flow under the strong force of the stator and rotor of the disperser, which usually has a strong dispersing and emulsifying effect on the material. Therefore, this type of high-speed mixer is also called a disperser. It is suitable for emulsification, mixing and dispersion of materials in chemical industries such as coatings, inks, paints, food, cosmetics, medicines, pesticides, petroleum, etc.

[0003] In the above industries, materials usually need to be fully stirred and refined to ensure product quality. However, the existing dispersers only disperse and grind the materials once, which makes it difficult to ensure the uniformity and refinement of the materials, and the production efficiency is low. Therefore, another process is required to stir and grind the materials, which increases production costs. Summary of the invention

[0004] The object of the present invention is to provide a disperser which performs two dispersion grindings on materials so that the materials can be fully processed, the dispersion effect is good and the production efficiency is high.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a disperser, including a horizontally placed pump body and a drive shaft, one end of the drive shaft is inside the pump body for driving a disperser rotor, and the other end extends outside the pump body and is connected to a power source, the disperser rotor includes a first rotor and a second rotor, the second rotor is sleeved on the outside of the first rotor and is radially spaced and the two rotors are coaxially arranged; the disperser also includes a stator fixedly connected to the pump body, the stator is inserted in the gap between the first rotor and the second rotor; the inner circumferential surface and the outer circumferential surface of the stator respectively form a gap with the outer circumferential surface of the first rotor and the inner circumferential surface of the second rotor for processing materials; the pump body is provided with a feed port and a discharge port, and the disperser rotor and the stator are located in a chamber between the feed port and the discharge port.

[0006] Preferably, the feed port includes a first feed port and a second feed port, and the two feed ports are dispersed at both ends of the material processing area. The first feed port is located on the pump body of the cylindrical pump body and at the lower part of the pump body; the second feed port is located on the end cover of the pump body, and is arranged in an inclined manner with the inlet at the top and the outlet at the bottom. The outlet of the second feed port in the pump body is located in the middle position of the end cover.

[0007] Preferably, a circular discharge port ring sleeve with an inner diameter larger than the inner diameter of the pump body is arranged between the pump body and the end cover, the discharge port is arranged on the discharge port ring sleeve and the outlet is upward, and a material processing chamber is formed between the discharge port ring sleeve, the pump body and the end cover; the disperser rotor and stator are both located in the material processing chamber, wherein the outer ring surface of the second rotor is in contact with the inner wall of the discharge port ring sleeve.

[0008] Preferably, the first rotor is mounted on the drive shaft through a sleeve extending from its middle to one side, and a fixing nut at the end of the drive shaft locks the first rotor to the drive shaft; the annular second rotor is fixed to the first rotor through a side plate and can rotate synchronously with the first rotor.

[0009] Preferably, the first rotor comprises a disc-shaped turntable, on the outer periphery of which are provided a plurality of first rotor blades protruding to one side, and the plurality of first rotor blades are evenly distributed along the outer periphery of the turntable; the outer side surface of the first rotor blade is an arc shape having the same curvature as the inner circumference of the stator.

[0010] Preferably, a threaded hole is provided on the first rotor blade, and a through hole is provided on the side plate of the second rotor, which passes through the plate surface and is compatible with the threaded hole. Screws pass through the through hole to fix the side plate of the second rotor against the first rotor blade. The second rotor is provided with a second rotor blade pointing opposite to the first rotor blade, and a gap is formed in the radial direction between the second rotor blade and the first rotor blade for inserting the stator.

[0011] Preferably, the annular stator is provided with a plurality of dispersion holes which are evenly distributed along the circumference of the annular plate surface and penetrate the plate surface; the dispersion holes include a first dispersion hole and a second dispersion hole which are arranged along the plate width direction; the stator is matched with the first rotor blade at the position of the first dispersion hole, and the first dispersion hole is a material discharge channel after the stator and the first rotor have dispersed and ground once; the stator is matched with the second rotor blade at the position of the second dispersion hole, and the second dispersion hole is a material discharge channel after the stator and the second rotor have dispersed and ground twice.

[0012] Preferably, the second rotor blades are evenly distributed along the outer periphery of the annular side plate, and the inner side surface of the second rotor blades is an arc with the same curvature as the outer peripheral surface of the stator; the number of the second rotor blades is consistent with the number of the first rotor blades, and the positions of the second rotor blades and the first rotor blades correspond to each other in sequence.

[0013] Preferably, the first dispersed holes and the second dispersed holes are both strip holes, and the planes where the hole lengths of the two holes are located form an angle; the width of the second dispersed holes is greater than the width of the first dispersed holes, and the number of the first dispersed holes arranged in the circumferential direction of the stator is greater than the number of the second dispersed holes.

[0014] Preferably, a stator base is provided at one end of the stator, and the stator is installed in the countersunk hole of the end cover through the stator base; the opening of the countersunk hole is inward-retracted, and the inner end surface of the stator base is provided with a convex ridge that cooperates with the inward-retracted countersunk hole, and a snap fit is formed between the stator base and the countersunk hole.

[0015] The beneficial effects of the present invention are:

[0016] 1) The incoming material from the feed port is guided through the pump cavity to the gap between the first rotor and the stator for primary dispersion and grinding. During the primary dispersion and grinding, the material is simultaneously subjected to a series of comprehensive forces such as centrifugal extrusion, liquid layer friction, and liquid layer impact. The material is initially dispersed and mixed. The high-speed rotating first rotor throws the material after the primary dispersion and grinding out of the primary dispersion and grinding area between the first rotor and the stator under the action of centrifugal force, and enters the space between the second rotor and the stator for secondary dispersion and grinding. The material is then subjected to a series of comprehensive forces such as centrifugal extrusion, liquid layer friction, and liquid layer impact. After that, the material generates a huge centrifugal force under the action of the high-speed rotating second rotor, and is ejected from the secondary dispersion and grinding area and enters the discharge port to complete the dispersion and mixing process of the material. This disperser performs two dispersion and grinding on the material, so that the material is fully processed, with good dispersion effect and high production efficiency.

[0017] 2) Arrange the two feed ports reasonably so that the materials can be fully dispersed and mixed after entering the pump body. Unused materials can be put into the first feed port and the second feed port. The materials entering the pump body reach the material processing areas where the disperser rotor and stator are located respectively. Under the strong centrifugal force of the first rotor and the second rotor, the materials are thrown into the gap between the first rotor and the stator for dispersion and mixing.

[0018] 3) An opening area is formed between the first rotor blade, the side plate and the second rotor blade. One end of the stator is inserted into the opening area to form a primary dispersing and grinding area and a secondary dispersing and grinding area between the first rotor blade and the second rotor blade respectively. The other end of the stator is fixedly connected to the end cover at the end of the pump body. When the disperser is repaired, it is only necessary to remove the end cover to pull the stator out of the pump body, and to remove the fixing nut to pull the first rotor and the second rotor out of the pump cavity of the pump body at the same time. The remaining parts can be disassembled in sequence, which is convenient for maintenance and user-friendly.

[0019] 4) After the material enters the material processing chamber from the first feed port and the second feed port, the first rotor blades and the second rotor blades generate strong centrifugal force to throw the material into the gap between the first rotor and the stator. After the material is dispersed and ground once, it is ejected at high speed through the first dispersion hole and enters the gap between the second rotor and the stator. The material is dispersed and ground twice, and finally, under the centrifugal force of the high-speed rotating second rotor, it is thrown into the discharge port and discharged out of the pump body. The material continuously enters from the first feed port and the second feed port, and forms a strong tumbling flocculent flow under the strong force of the stator and rotor of the disperser to fully disperse and mix, thereby realizing the function of the disperser.

[0020] 5) The size of the first dispersion hole and the second dispersion hole is directly related to the size of the material after dispersion and grinding. The user decides based on the actual application. The width of the second dispersion hole is greater than the width of the first dispersion hole in order to make it easier for the second rotor to throw the material out of the material processing chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the stator and rotor parts of the present invention;

[0023] Figure 3 is a schematic diagram of the structure of the first rotor;

[0024] Figure 4 is a cross-sectional schematic diagram of the first rotor;

[0025] Figure 5 is a schematic diagram of the structure of the second rotor;

[0026] Figure 6 is a schematic cross-sectional view of the second rotor;

[0027] Figure 7 A schematic diagram of the structure of assembling the first rotor and the second rotor;

[0028] Figure 8 Schematic diagram of the stator structure. DETAILED DESCRIPTION

[0029] For ease of understanding, the present invention is described in detail below with reference to the accompanying drawings.

[0030] A disperser includes a horizontally placed pump body 10 and a drive shaft 20, one end of the drive shaft 20 is inside the pump body 10 for driving a disperser rotor, and the other end extends outside the pump body 10 to be connected to a power source, the disperser rotor includes a first rotor 31 and a second rotor 32, the second rotor 32 is sleeved on the outside of the first rotor 31 with radial spacing and the two rotors are coaxially arranged; the disperser also includes a stator 40 fixedly connected to the pump body 10, the stator 40 is inserted in the gap between the first rotor 31 and the second rotor 32; the inner circumference and outer circumference of the stator 40 respectively form gaps with the outer circumference of the first rotor 31 and the inner circumference of the second rotor 32 for processing materials; the pump body 10 is provided with a feed port and a discharge port 11, and the disperser rotor and the stator 40 are located in a chamber between the feed port and the discharge port 11. The material enters the pump body 10 from the feed port, and the drive shaft 20 drives the first rotor 31 to rotate at a high speed at this time. The incoming material from the feed port is guided to the gap between the first rotor 31 and the stator 40 through the pump cavity for a dispersion and grinding. During the first dispersion and grinding, the material is simultaneously subjected to a series of comprehensive forces such as centrifugal extrusion, liquid layer friction, and liquid layer impact, and the material is initially dispersed and mixed. The first rotor 31 rotating at a high speed throws the material after the first dispersion and grinding out of the first dispersion and grinding area between the first rotor 31 and the stator 40 under the action of centrifugal force, and enters the second rotor 32 and the stator 40 for a secondary dispersion and grinding. The material is then subjected to a series of comprehensive forces such as centrifugal extrusion, liquid layer friction, and liquid layer impact. After that, the material generates a huge centrifugal force under the action of the second rotor 32 rotating at a high speed, and is ejected from the secondary dispersion and grinding area and enters the discharge port 11 to complete the dispersion and mixing process of the material. The disperser performs two dispersion and grinding on the material, so that the material is fully processed, the dispersion effect is good, and the production efficiency is high.

[0031] In order to mix multiple materials, the feed inlet includes a first feed inlet 121 and a second feed inlet 122, and the two feed inlets are dispersed at both ends of the material processing area. The first feed inlet 121 is located on the pump body of the cylindrical pump body 10 and is located at the lower part of the pump body 10, and the material is pumped into the pump body 10 from the lower part of the pump body 10; the second feed inlet 122 is located on the end cover 13 of the pump body 10, and is arranged in an inclined manner with the inlet at the top and the outlet at the bottom. The outlet of the second feed inlet 122 in the pump body 10 is located in the middle of the end cover 13. The two feed inlets are arranged reasonably so that the materials can be fully dispersed and mixed after entering the pump body 10. Unused materials can be put into the first feed inlet 121 and the second feed inlet 122. The materials entering the pump body 10 reach the material processing area where the disperser rotor and the stator 40 are located respectively. Under the strong centrifugal force of the first rotor 31 and the second rotor 32, the materials are thrown into the gap between the first rotor 31 and the stator 40 for dispersion and mixing.

[0032] A circular discharge port ring sleeve 111 with an inner diameter larger than that of the pump body 10 is arranged between the pump body 10 and the end cover 13. The discharge port 11 is arranged on the discharge port ring sleeve 111 and the outlet is upward. A material processing chamber is formed between the discharge port ring sleeve 111, the pump body 10 and the end cover 13. The disperser rotor and stator 40 are both located in the material processing chamber, wherein the outer ring surface of the second rotor 32 is in contact with the inner wall of the discharge port ring sleeve 111. When the material enters from the first feed port 121, it reaches the material processing chamber along the pump cavity of the pump body 10, and when the material enters from the second feed port 122, it directly enters the material processing chamber. A circular discharge port ring sleeve 111 with an inner diameter larger than the inner diameter of the pump body 10 is arranged between the pump body 10 and the end cover 13. The large-diameter discharge port ring sleeve 111 is more convenient for the installation of the disperser rotor and the stator 40 in the pump body 10, and there is sufficient installation space. At the same time, it is also for the convenience of the dispersed and mixed materials to be ejected in the material processing chamber, so as to facilitate the discharge of the materials.

[0033] The first rotor 31 is sleeved on the drive shaft 20 through a sleeve 311 extending from the middle to one side, and the fixing nut 21 at the end of the drive shaft 20 locks the first rotor 31 and the drive shaft 20; the annular second rotor 32 is fixed to the first rotor 31 through a side plate 321 and can achieve synchronous rotation with the first rotor 31. The second rotor 32 is fixedly connected to the first rotor 31, on the one hand, so that the two have synchronous rotation speeds, and on the other hand, when the material enters from the first feed port 121, if the second rotor 32 is also connected to the drive shaft 20 with the same structure as the first rotor 31, the connection structure will interfere with the material entering the material processing chamber, affecting the normal use of the disperser, so the present invention adopts the method of fixing the second rotor 32 on the first rotor 31 through the side plate 321 and achieving synchronous rotation with the first rotor 31.

[0034] More specifically, the first rotor 31 includes a disc-shaped rotating disk 312, and a plurality of first rotor blades 313 protruding to one side are provided on the outer periphery of the rotating disk 312, and the plurality of first rotor blades 313 are evenly distributed along the outer periphery of the rotating disk 312; the outer side surface of the first rotor blade 313 is an arc shape consistent with the curvature of the inner peripheral surface of the stator 40. The material is processed by utilizing the centrifugal extrusion, liquid layer friction, liquid layer collision and other effects formed between the high-speed rotating first rotor blade 313 and the stator 40, so that the material is fully dispersed and mixed. At the same time, the outer side surface of the first rotor blade 313 is an arc shape consistent with the curvature of the inner peripheral surface of the stator 40, ensuring that the force generated between the first rotor blade 313 and the stator 40 at all locations during rotation is consistent, so that the processing is more uniform.

[0035] More specifically, the structure between the first rotor 31 and the second rotor 32 is as follows: the first rotor blade 313 is provided with a threaded hole 314; the side plate 321 of the second rotor 32 is provided with a through hole 322 that passes through the plate surface and matches the threaded hole 314; the screw 323 passes through the through hole 322 to fix the side plate 321 of the second rotor 32 against the first rotor blade 313; the second rotor 32 is provided with a second rotor blade 324 that points opposite to the first rotor blade 313; a gap for inserting the stator 40 is formed in the radial direction between the second rotor blade 324 and the first rotor blade 313, that is, an open area is formed between the first rotor blade 313, the side plate 321 and the second rotor blade 324; one end of the stator 40 is inserted into the open area to form a primary dispersion and grinding area and a secondary dispersion and grinding area with the first rotor blade 313 and the second rotor blade 324, respectively; the other end of the stator 40 is fixedly connected to the end cover 13 at the end of the pump body 10. When the disperser is to be repaired, it is only necessary to remove the end cover 13 to pull out the stator 40 from the pump body 10, and to remove the fixing nut 21 to simultaneously pull out the first rotor 31 and the second rotor 32 from the pump cavity of the pump body 10, and the remaining components can be disassembled in sequence, which is convenient for maintenance and user-friendly.

[0036] The annular stator 40 is provided with a plurality of dispersion holes which are evenly distributed along the circumference of the annular plate surface and penetrate the plate surface; the dispersion holes include a first dispersion hole 41 and a second dispersion hole 42 which are arranged along the plate width direction; the stator 40 is adapted to the first rotor blade 313 at the position of the first dispersion hole 41, and the first dispersion hole 41 is a material discharge channel after the stator 40 and the first rotor 31 have dispersed and ground once; the stator 40 is adapted to the second rotor blade 324 at the position of the second dispersion hole 42, and the second dispersion hole 42 is a material discharge channel after the stator 40 and the second rotor 32 have dispersed and ground twice. The specific working process is as follows: after the material enters the material processing chamber from the first feed port 121 and the second feed port 122, since there is a certain angle α between the side of the first rotor blade 313 and the plane where the axis is located, the angle α is generally 5°<α<15° in the actual production process, and similarly, there is a certain angle β between the side of the second rotor blade 324 and the plane where the axis is located, and the angle β is equal to the angle α, such as Figure 7As shown, in this embodiment, the angle β and the angle α are both selected as 10°. The setting of the angle enables the first rotor blade 313 and the second rotor blade 324 to generate a stronger centrifugal force to throw the material into the gap between the first rotor 31 and the stator 40. After the material is dispersed and ground once, it is ejected at high speed through the first dispersion hole 41 and enters the gap between the second rotor 32 and the stator 40. The material is dispersed and ground twice, and finally, under the centrifugal force of the high-speed rotating second rotor 32, it is thrown into the discharge port 11 and discharged from the pump body 10. The material continuously enters from the first feed port 121 and the second feed port 122, and forms a strong tumbling flocculent flow under the strong action of the stator and rotor of the disperser to fully disperse and mix, thereby realizing the function of the disperser.

[0037] The second rotor blades 324 are evenly distributed along the outer periphery of the annular side plate 321, and the inner side surface of the second rotor blades 324 is an arc shape with the same curvature as the outer peripheral surface of the stator 40; the number of the second rotor blades 324 is consistent with the number of the first rotor blades 313, and the positions of the second rotor blades 324 and the first rotor blades 313 correspond in sequence.

[0038] The first dispersion holes 41 and the second dispersion holes 42 are both strip holes, and the planes where the hole lengths of the two holes are located form an angle; the width of the second dispersion holes 42 is greater than the width of the first dispersion holes 41, and the number of the first dispersion holes 41 arranged in the circumferential direction of the stator 40 is greater than the number of the second dispersion holes 42. The size of the first dispersion holes 41 and the second dispersion holes 42 is directly related to the size of the dispersed and ground materials, and the user decides according to actual application. The width of the second dispersion holes 42 is greater than the width of the first dispersion holes 41 in order to make it easier for the second rotor 32 to throw the materials out of the material processing chamber.

[0039] A stator base 43 is provided at one end of the stator 40, and the stator 40 is installed in the countersunk hole 131 of the end cover 13 through the stator base 43; the opening of the countersunk hole 131 is inward-retracted, and the inner end surface of the stator base 43 is provided with a convex ridge that cooperates with the inward-retracted countersunk hole 131, and a snap fit is formed between the stator base 43 and the countersunk hole 131.

Claims

1. A disperser, comprising a horizontally placed pump body (10) and a drive shaft (20), wherein one end of the drive shaft (20) is inside the pump body (10) for driving a disperser rotor, and the other end extends outside the pump body (10) to be connected to a power source, characterized in that: The disperser rotor comprises a first rotor (31) and a second rotor (32), wherein the second rotor (32) is sleeved on the outside of the first rotor (31) in a radially spaced manner and the two rotors are coaxially arranged; the disperser further comprises a stator (40) fixedly connected to the pump body (10), wherein the stator (40) is inserted into the gap between the first rotor (31) and the second rotor (32); the gap formed between the inner circumference and the outer circumference of the stator (40) and the outer circumference of the first rotor (31) and the inner circumference of the second rotor (32) is used for processing materials; the pump body (10) is provided with a feed port and a discharge port (11), and the disperser rotor and the stator (40) are located between the feed port and the discharge port. The first rotor (31) is provided with a first feed port (121) and a second feed port (122), and the two feed ports are dispersed at two ends of the material processing area. The first feed port (121) is located on the pump body of the cylindrical pump body (10) and is located at the lower part of the pump body (10). The second feed port (122) is located on the end cover (13) of the pump body (10) and is arranged in an inclined manner with the inlet at the top and the outlet at the bottom. The outlet of the second feed port (122) in the pump body (10) is located in the middle of the end cover (13). The first rotor (31) is sleeved on the drive shaft (20) through a shaft sleeve (311) extending from the middle to one side. The fixing nut (21) of the first rotor (31) is used to lock the first rotor (31) and the drive shaft (20); the annular second rotor (32) is fixed to the first rotor (31) through the side plate (321) and can realize synchronous rotation with the first rotor (31); the first rotor (31) includes a disc-shaped rotating disk (312); a plurality of first rotor blades (313) protruding toward one side are provided on the outer periphery of the rotating disk (312), and the plurality of first rotor blades (313) are evenly distributed along the outer periphery of the rotating disk (312); the outer side surface of the first rotor blade (313) is an arc shape with the same arc as the inner peripheral surface of the stator (40); the first rotor blade (313) is provided with a threaded hole ( 314), a through hole (322) penetrating the plate surface and matching the threaded hole (314) is provided on the side plate (321) of the second rotor (32), a screw (323) passes through the through hole (322) to fix the side plate (321) of the second rotor (32) against the first rotor blade (313), the second rotor (32) is provided with a second rotor blade (324) pointing in the opposite direction to the first rotor blade (313), and a gap for inserting the stator (40) is formed in the radial direction between the second rotor blade (324) and the first rotor blade (313); the annular stator (40) is provided with a plurality of dispersed holes evenly distributed along the circumference of the annular plate surface and penetrating the plate surface;The dispersion holes include a first dispersion hole (41) and a second dispersion hole (42) arranged along the width direction of the plate; the stator (40) is matched with the first rotor blade (313) at the position of the first dispersion hole (41); the first dispersion hole (41) is a material discharge channel after the stator (40) and the first rotor (31) disperse and grind the material once; The stator (40) is matched with the second rotor blade (324) at the position of the second dispersion hole (42), and the second dispersion hole (42) is a material discharge channel after secondary dispersion and grinding between the stator (40) and the second rotor (32).

2. A disperser according to claim 1, characterized in that: A circular discharge port ring sleeve (111) having an inner diameter greater than the inner diameter of the pump body (10) is arranged between the pump body (10) and the end cover (13); the discharge port (11) is arranged on the discharge port ring sleeve (111) and the outlet is upward; a material processing chamber is formed between the discharge port ring sleeve (111), the pump body (10) and the end cover (13); the disperser rotor and stator (40) are both located in the material processing chamber, wherein the outer ring surface of the second rotor (32) is in contact with the inner wall of the discharge port ring sleeve (111).

3. A disperser according to claim 1, characterized in that: The second rotor blades (324) are evenly distributed along the outer periphery of the annular side plate (321), and the inner side surface of the second rotor blades (324) is an arc shape having the same arc as the outer peripheral surface of the stator (40); the number of the second rotor blades (324) is consistent with the number of the first rotor blades (313), and the positions of the second rotor blades (324) and the first rotor blades (313) correspond in sequence.

4. A disperser according to claim 3, characterized in that: The first dispersion holes (41) and the second dispersion holes (42) are both strip-shaped holes, and the planes where the hole lengths of the two holes are located form an angle; the width of the second dispersion holes (42) is greater than the width of the first dispersion holes (41), and the number of the first dispersion holes (41) arranged in the circumferential direction of the stator (40) is greater than the number of the second dispersion holes (42).

5. A disperser according to claim 2, characterized in that: A stator base (43) is provided at one end of the stator (40), and the stator (40) is installed in the countersunk hole (131) of the end cover (13) through the stator base (43); the opening of the countersunk hole (131) is in an inward-retracted shape, and the inner end surface of the stator base (43) is provided with a convex ridge that matches the inward-retracted countersunk hole (131), and a snap fit is formed between the stator base (43) and the countersunk hole (131).

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