A permanent ferrite counter-pressure magnetic tile mold

Abstract

The present invention discloses a permanent ferrite counter-pressure magnetic tile mold, comprising a middle mold, several upper mold bases, and several punch bases. The top profile of the middle mold includes an arc segment R1 located in the middle and arc segments R2, R3, and R4 symmetrically distributed on both sides. The two ends of the arc segment R1 are connected to the arc segments R2, R3, and R4 in sequence. The two sides of the arc segment R1 gradually rise, the arc segments R2 to R3 gradually decrease, and the arc segments R3 to R4 gradually rise. The bottom profile of the upper mold base is consistent with the top profile of the middle mold, so that the compression ratio of each part of the green body is basically consistent. An upper mold inlay is provided below the upper mold base, and a punch inlay is provided on the punch base, so that the direction of the magnetic force lines on both sides of the magnetic tile green body also tends to be vertical. By adjusting the compression ratio and changing the direction of the magnetic force lines, the density of each part of the green body is more consistent, thereby completely solving the problem of knife edge cracking.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic tile processing, in particular to a permanent ferrite counter-pressure magnetic tile mould. Background Art

[0002] Permanent ferrite magnetic tiles are mainly used in automobiles, home appliances, power tools, etc., and are used to make micro motors. The working surfaces of permanent ferrite magnetic tiles have two types: outer arc surface and inner arc surface.

[0003] The permanent ferrite magnet tile forming equipment primarily consists of a hydraulic press, mold, and coil. Because the coil surrounds the vertical mold, magnetic lines of force form a closed magnetic field through the press and mold during the pressing process. During the permanent ferrite mold forming process, immediately after the hydraulic press closes the mold, the slurry is injected into the mold cavity through the injection port for magnetization. This magnetization is then applied simultaneously during the pressing process. During the molding process, the coil magnetic field radially magnetizes the slurry in the mold. When the set pressure is reached, the molding process concludes. The pressed green body is sintered in a kiln and then ground to the dimensions specified by the customer's drawings. Finally, it is cleaned and packaged.

[0004] Permanent ferrite magnetic tiles are mainly used in automobiles, home appliances, power tools, etc., and are used to make micro motors. The working surfaces of permanent ferrite magnetic tiles have two types: outer arc surface and inner arc surface.

[0005] Permanent ferrite molds are divided into positive pressure molds and negative pressure molds. Negative pressure products use an outer arc working surface, with the inner arc pointing upward and the outer arc pointing downward. Products pressed with positive pressure molds have an inner arc higher than the outer arc. Because the magnetic field is oriented radially from the inner arc of the punch to the outer arc, the inner arc has a higher magnetic field density and a higher magnetic field than the outer arc. The inner arc surface of the permanent ferrite tile is used as the working surface. Products pressed with negative pressure molds have an outer arc higher than the inner arc. Because the magnetic field is oriented radially from the outer arc of the punch to the inner arc, the outer arc has a higher magnetic field density and a higher magnetic field than the inner arc. The outer arc surface of the permanent ferrite tile is used as the working surface.

[0006] In order to prevent cracks in the inner arc corners of the currently known permanent magnet ferrite counter-pressure magnetic tiles, the inner arc corners are usually designed to be horizontal and then ground, which greatly increases the production cost. Another method is to directly use the horizontal as a reference and directly warp a certain degree, but this method is prone to knife-edge crack defects during molding. Summary of the Invention

[0007] The purpose of the present invention is to provide a permanent magnet ferrite counter-pressure magnetic tile mold to solve the problems raised by the above background technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A permanent magnet ferrite counter-pressure magnetic tile mold includes a middle mold, several upper mold bases and several punch bases. The top profile contour line of the middle mold includes an arc segment R1 located in the middle and arc segments R2, R3 and R4 symmetrically distributed on both sides. The two ends of the arc segment R1 are connected to the arc segments R2, R3 and R4 in sequence. The two sides of the arc segment R1 gradually rise, the arc segments R2 to R3 gradually decrease, and the arc segments R3 to R4 gradually rise. The bottom profile contour line of the upper mold base is consistent with the top profile contour line of the middle mold.

[0010] As a further solution of the present invention: the arc segment R1 is tangentially connected to the arc segment R2, the arc segment R2 is tangentially connected to the arc segment R3, and the arc segment R3 is tangentially connected to the arc segment R4.

[0011] As a further solution of the present invention: an upper mold inlay is arranged below the upper mold base, and the upper mold inlay is symmetrically distributed on both sides of the magnetic tile green body.

[0012] As a further solution of the present invention: the upper mold inlays on both sides are located outside the extension lines of the two side edges of the corresponding magnetic tile green body.

[0013] As a further solution of the present invention: the thickness of the upper mold inlay is the same as the thickness of the magnetic tile green body.

[0014] As a further solution of the present invention: a punch inlay is provided on the punch base, the punch inlay is located below the top profile of the punch base, and the punch inlay is thick in the middle and thin at both sides.

[0015] As a further solution of the present invention: the upper mold inlay and the punch inlay are both made of weakly magnetic stainless steel.

[0016] As a further solution of the present invention: the middle thickness of the male mold inlay is 5-20 mm, and the thickness on both sides gradually decreases to 0 mm.

[0017] Beneficial effects of the present invention:

[0018] The present invention processes three mutually connected arc segments R2, R3 and R4 on both sides of the middle arc segment R1 of the permanent magnet ferrite counter-pressure mold, and gradually increases the arc segment R1 on both sides, gradually decreases from the arc segment R2 to the arc segment R3, and gradually increases from the arc segment R3 to the arc segment R4; so that the compression ratio b / B increases and the compression ratio c / C decreases, so that the final compression ratios a / A, b / B and c / C are basically consistent, the density of each part of the molded green body is basically consistent, and the reduction Reducing compression ratio differences among various parts of the green blank reduces the amount of angular grinding on both sides of the magnetic tile during grinding. Furthermore, a weakly magnetic stainless steel upper die insert is placed beneath the upper die base to reduce the dispersion of magnetic lines of force. A weakly magnetic stainless steel punch insert is placed on the punch base to disperse the magnetic lines of force near the punch base. The dual coordination of the upper die insert and the punch insert makes the magnetic lines of force perpendicular, and thus also perpendicular, on both sides of the magnetic tile green blank. By adjusting the compression ratio and changing the direction of the magnetic lines of force, the density of each part of the green blank becomes more consistent, thus completely resolving the problem of knife-edge cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 for Figure 1 A partial enlarged view of point D in the middle;

[0022] Figure 3 It is a schematic diagram of the green structure of magnetic tiles in the prior art;

[0023] Figure 4 It is a schematic diagram of the structure of the magnetic tile green body pressed by the present invention.

[0024] In the figure: 1, middle mold; 2, upper mold base; 3, punch base; 4, injection hole; 5, magnetic tile green body; 6, upper mold inlay; 7, punch inlay; 8, horizontal angle. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making any creative efforts shall fall within the scope of protection of the present invention.

[0026] See also Figure 1As shown, the permanent magnet ferrite counter-pressure magnetic tile mold includes a middle mold 1, several upper mold bases 2 and several punch bases 3. Several cavities are set on the middle mold 1, the upper and lower ends of the cavity are connected, and injection holes 4 are opened on the side walls of the cavity; the upper mold base 2 and the punch base 3 are used as a set and are respectively adapted to the two ends of the cavity on the middle mold 1; the upper mold base 2, the punch base 3 and the middle mold 1 are combined, and the slurry is injected into the cavity through the injection hole 4, and the magnetic tile green body 5 is formed by pressing and molding with a hydraulic press.

[0027] In this embodiment, please refer to Figure 4 As shown, the top profile contour line of the middle mold 1 includes an arc segment R1 located in the middle and arc segments R2, R3 and R4 symmetrically distributed on both sides. The two ends of the arc segment R1 are connected to the arc segments R2, R3 and R4 in sequence, wherein the arc segment R1 is tangentially connected to the arc segment R2, the arc segment R2 is tangentially connected to the arc segment R3, and the arc segment R3 is tangentially connected to the arc segment R4; the two sides of the arc segment R1 gradually rise, the arc segment R2 to the arc segment R3 gradually decreases, and the arc segment R3 to the arc segment R4 gradually rises; the bottom profile contour line of the upper mold base 2 is consistent with the top profile contour line of the middle mold 1.

[0028] Please note that Figure 2 As shown in the figure, before the green compact is pressed, that is, when the punch base 3 is in the initial state (the punch base 3 is not closed), the height difference between the lowest point of the top profile of the punch base 3 (that is, the center of the inner arc surface) and the lowest point of the top profile of the center mold 1 (that is, the center of the arc segment R1) is recorded as a; the height difference between the two side edges of the top profile of the punch base 3 and the highest points of the two side edges of the top profile of the center mold 1 (that is, the connection between the arc segment R2 and the arc segment R3) is recorded as b; the height difference between the two side edges of the top profile of the punch base 3 and the lowest point of the two side edges of the top profile of the center mold 1 (that is, the lowest point of the arc segment R4) is recorded as c;

[0029] Likewise, see Figure 3 and Figure 4 As shown in the figure, after the green compact is pressed, that is, when the punch base 3 is in the mold closing state, the height difference between the lowest point of the top profile of the punch base 3 (that is, the center of the inner arc surface) and the lowest point of the top profile of the center mold 1 (that is, the center of the arc segment R1) is recorded as A; the height difference between the two side edges of the top profile of the punch base 3 and the highest points of the two side edges of the top profile of the center mold 1 (that is, the connection between the arc segment R2 and the arc segment R3) is recorded as B; the height difference between the two side edges of the top profile of the punch base 3 and the lowest point of the two side edges of the top profile of the center mold 1 (that is, the lowest point of the arc segment R4) is recorded as C;

[0030] Furthermore, it can be concluded that the compression ratios at three points of the pressed magnetic tile green body 5 are a / A, b / B and c / C respectively, and the compression ratio at each point represents the density of each part of the magnetic tile green body 5.

[0031] In the prior art, in order to prevent cracks from forming at the corners of the inner arc surface of the pressed magnetic tile, the through grooves are designed to form a horizontal angle 8 on both sides of the top molding surface of the middle mold 1, so that the sides of the pressed green body present the same horizontal angle 8. This will lead to an uneven distribution of compression ratios at three points of the existing green body, showing a trend of c / C>a / A>b / B, and the overall density of the green body is inconsistent, which makes it easy for knife-edge cracks to occur.

[0032] This embodiment processes three mutually connected arc segments R2, arc segment R3 and arc segment R4 on both sides of the arc segment R1, and gradually raises the two sides of the arc segment R1, gradually lowers the arc segment R2 to the arc segment R3, and gradually raises the arc segment R3 to the arc segment R4; in this way, compared with the existing technology, the height difference b and the height B increase, the height difference c and the height difference C decrease, and the increase in height difference b is smaller than the increase in height difference B, and the increase in height difference c is smaller than the increase in height difference C, so that the compression ratio b / B increases and the compression ratio c / C decreases, so that the final compression ratios a / A, b / B and c / C are basically consistent, the density of each part of the formed green body is basically consistent, the compression ratio difference of each part of the green body is reduced, and the angle grinding amount on both sides of the magnetic tile during grinding of the green body can be reduced.

[0033] Also, see Figure 3 As shown, in the prior art, since the upper mold base 2 and the punch base 3 are made of magnetic pure iron, and the middle mold 1 is made of weakly magnetic stainless steel, the direction of the magnetic lines of force is radially arranged from the punch base 3 to the upper mold base 2, and the slurry is also radially arranged when magnetized in the mold cavity. Due to the influence of the magnetic field, the magnetic lines of force on both sides of the green body (i.e. Figure 3 The direction of the straight line with arrows in the middle diverges to the left and right sides respectively.

[0034] In this embodiment, please refer to Figure 4 As shown, in order to guide the direction of the magnetic lines of force from the punch through the green to the upper mold, the direction of the magnetic lines of force tends to be vertical, an upper mold inlay 6 is set below the upper mold base 2, and the upper mold inlay 6 is symmetrically distributed on both sides of the magnetic tile green 5. The upper mold inlay 6 is made of weak magnetic stainless steel, which can reduce the dispersion of the magnetic lines of force to both sides and make the direction of the magnetic lines of force tend to be vertical, so that the magnetic lines of force on both sides of the magnetic tile green 5 (i.e. Figure 4 The direction of the straight line with an arrow in the middle also tends to be vertical.

[0035] It should be noted that the upper mold inlays 6 on both sides are located outside the extension lines of the corresponding two side edges of the magnetic tile green body 5 , and the thickness of the upper mold inlays 6 is the same as that of the magnetic tile green body 5 .

[0036] Similarly, a punch inlay 7 is provided on the punch base 3. The punch inlay 7 is located below the top profile of the punch base 3, and the punch inlay 7 is thick in the middle and thin on both sides. The punch inlay 7 is made of weakly magnetic stainless steel, which can make the direction of the magnetic lines of force close to the punch base 3 diverge to both sides, so that the direction of the magnetic lines of force close to the punch base 3 tends to be vertical, thereby making the direction of the magnetic lines of force on both sides of the magnetic tile green body 5 (i.e., the straight lines with arrows in the figure) also tend to be vertical.

[0037] It should be noted that the thickness of the male mold inlay 7 is 5-20 mm in the middle, and the thickness on both sides gradually decreases to 0 mm.

[0038] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A permanent ferrite counter-pressure magnetic tile mold, comprising a middle mold (1), a plurality of upper mold bases (2) and a plurality of punch bases (3), characterized in that: The contour line of the top profile of the middle mold (1) includes an arc segment R1 located in the middle and arc segments R2, R3 and R4 symmetrically distributed on both sides, and both ends of the arc segment R1 are connected to the arc segments R2, R3 and R4 in sequence; The two sides of arc segment R1 gradually rise, arc segment R2 to arc segment R3 gradually fall, and arc segment R3 to arc segment R4 gradually rise; The contour line of the bottom profile of the upper mold base (2) is consistent with the contour line of the top profile of the middle mold (1); The arc segment R1 is tangentially connected to the arc segment R2, the arc segment R2 is tangentially connected to the arc segment R3, and the arc segment R3 is tangentially connected to the arc segment R4; Before the green compact is pressed, when the punch base (3) is not closed, the height difference between the lowest point of the top profile of the punch base (3) and the lowest point of the top profile of the middle mold (1) is recorded as a; the height difference between the highest points of the two side edges of the top profile of the punch base (3) and the two side edges of the top profile of the middle mold (1) is recorded as b; the height difference between the lowest points of the two side edges of the top profile of the punch base (3) and the two side edges of the top profile of the middle mold (1) is recorded as c; After the green compact is pressed, when the punch base (3) is in the mold closing state, the height difference between the lowest point of the top profile of the punch base (3) and the lowest point of the top profile of the middle mold (1) is recorded as A; the height difference between the highest points of the two side edges of the top profile of the punch base (3) and the two side edges of the top profile of the middle mold (1) is recorded as B; the height difference between the lowest points of the two side edges of the top profile of the punch base (3) and the two side edges of the top profile of the middle mold (1) is recorded as C; The compression ratios at three points of the pressed magnetic tile green body (5) are a / A, b / B and c / C respectively; a / A, b / B and c / C are basically the same.

2. A permanent magnet ferrite counter-pressure magnetic tile mold according to claim 1, characterized in that: An upper mold inlay (6) is provided below the upper mold base (2), and the upper mold inlay (6) is symmetrically distributed on both sides of the magnetic tile green body (5).

3. The permanent magnet ferrite counter-pressure magnetic tile mold according to claim 2, characterized in that: The upper mold inlays (6) on both sides are located outside the extension lines of the two side edges of the corresponding magnetic tile green body (5).

4. A permanent magnet ferrite counter-pressure magnetic tile mold according to claim 2, characterized in that: The thickness of the upper mold inlay (6) is the same as the thickness of the magnetic tile green body (5).

5. The permanent magnet ferrite counter-pressure magnetic tile mold according to claim 2, characterized in that: A punch inlay (7) is provided on the punch base (3), the punch inlay (7) is located below the top profile of the punch base (3), and the punch inlay (7) is thick in the middle and thin at both sides.

6. The permanent magnet ferrite counter-pressure magnetic tile mold according to claim 5, characterized in that: The middle thickness of the male mold inlay (7) is 5-20 mm, and the thickness of both sides of the male mold inlay (7) gradually decreases to 0 mm.

7. The permanent magnet ferrite counter-pressure magnetic tile mold according to claim 5, characterized in that: The upper mold inlay (6) and the punch inlay (7) are both made of weakly magnetic stainless steel.

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