Manufacturing method and mold of conical tank

Abstract

The invention discloses a manufacturing method of a conical tank, which comprises the following steps: a plurality of sub-sections which are sequentially arranged in the height direction are formed on the side wall of a blank tank by adopting a multi-pass tapering process, and each sub-section comprises a straight wall section and a conical section; shaping the side wall of the blank tank to form a tank body of which the upper part is a straight wall and the other part is a conical wall with a target taper; and tank opening expanding and tank bottom forming are conducted, so that the target conical tank is obtained. The invention further discloses a die for manufacturing the conical can, the die comprises a plurality of sets of tapering dies corresponding to the multi-pass tapering process, each set of tapering die comprises a tapering male die and a tapering female die, and the tapering male die is used for the outer wall of the current-pass forming part and the inner wall of the tapering female die and comprises a straight wall part and a conical part; the shaping die comprises a shaping male die and a shaping female die, the shaping male die and the shaping female die each comprise a shaping straight wall part and a shaping conical part, and the taper angle of each shaping conical part is set to be the target taper.

Description

TECHNICAL FIELD

[0001] The present application relates to a forming method and a die thereof, in particular to a manufacturing method of a can body and a die thereof. BACKGROUND

[0002] Two-piece cans are composed of a can body and a top cover, and two-piece cans include straight-wall two-piece cans with straight-wall can bodies and conical cans with conical can bodies.

[0003] For conical cans with small cone angles and small heights, a matched conical punch and a matched conical die are used in combination with an applied blank holder force to obtain the conical cans by stamping forming, so that wrinkles on the can wall during forming can be avoided.

[0004] However, the above conventional method is not applicable to conical cans with large heights and certain cone angles. When the cone angle is certain, the larger the height of the can is, the larger the difference between the diameters of the can mouth and the can bottom is, which requires that the difference between the diameters of the upper part and the lower part of the punch is also larger. In addition, considering the required gap between the inner die and the outer die due to the thickness of the sheet, the diameter of the bottom of the die should be larger than the diameter of the lower part of the punch, so that the difference between the diameter of the bottom of the die and the diameter of the upper part of the punch is larger. When the conventional stretch forming method is used, the upper part of the punch with a small diameter first contacts the blank can, and at this time, the gap between the inner die and the outer die is much larger than the normal gap between the inner die and the outer die, which inevitably leads to wrinkles on the can wall. Such wrinkles cannot be eliminated by increasing the blank holder force.

[0005] Based on this problem, Japanese Patent Document No. JP476178B2 uses a method of first obtaining a blank can with a target can mouth diameter by stretching, then forming a blank can with several straight-wall segments with diameters gradually decreasing from the can mouth to the can bottom by several pressing processes, and finally forming a can wall with a target cone angle by using a conical punch and a conical die. The blank can before the final forming process is mainly composed of straight-wall segments and is supplemented by short inclined surfaces.

[0006] Therefore, how to provide a processing die and a method for conical cans, so that no wrinkles or transition marks are generated on the can wall during the forming process of the two-piece conical cans, is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0007] One of the purposes of the present application is to provide a manufacturing method for conical cans, which aims to solve the problem that wrinkles are easily generated on the can wall during the forming of the conical cans in the prior art.

[0008] In order to achieve the above-mentioned purpose, the present application provides a manufacturing method for conical cans, which comprises the following steps:

[0009] A multi-pass conical drawing process is used to form a plurality of sub-segments arranged in sequence in the height direction of the side wall of the blank can, wherein each sub-segment includes a straight-wall segment and a conical segment connected thereto.

[0010] The side walls of the blank tank are shaped to form a tank body with a straight upper wall and a tapered wall with a target taper in the remaining part;

[0011] The can opening is enlarged and the bottom is formed to obtain the target conical can.

[0012] As can be seen, the manufacturing method of the present invention forms several tank wall segments that combine straight wall segments and conical segments through a multi-pass tapering process. After the tank wall is shaped, a conical tank with a straight wall at the top and the target taper at the bottom is formed. Finally, the target conical tank is obtained by expanding the tank opening and forming the arched bottom of the tank.

[0013] Furthermore, in the manufacturing method described in this invention, the multi-pass tapering process is at least a three-pass tapering process.

[0014] Furthermore, in the manufacturing method described in this invention, in each tapering process, the tapering punch and tapering die have the same tapered angle.

[0015] Furthermore, in the manufacturing method described in this invention, when the sidewall of the blank can is formed into three segments arranged sequentially in the height direction using a three-pass tapering process, the cone angle of the tapered portion of the tapering punch and tapering die used in the first tapering process is 2.5-3°; the cone angle of the tapered portion of the tapering punch and tapering die used in the second tapering process is 3-4°; and the cone angle of the tapered portion of the tapering punch and tapering die used in the third tapering process is 3-4°.

[0016] Furthermore, in the manufacturing method described in this invention, for each sub-segment, the ratio of the height of the straight-walled segment to the height of the tapered segment is 0.9-1.1.

[0017] Furthermore, in the manufacturing method described in this invention, the height of the straight wall section formed by the first tapering process is less than the height of the straight wall section formed by subsequent tapering processes.

[0018] Another object of the present invention is to provide a mold for manufacturing conical cans to implement the above-described manufacturing method, thereby solving the problem of can wall wrinkles that are easily generated during the forming of conical cans in the prior art.

[0019] To achieve the above objectives, the present invention also provides a mold for manufacturing conical cans, comprising:

[0020] A number of sets of tapered dies corresponding to a multi-pass tapering process are provided. Based on the multi-pass tapering process, the sidewall of the blank can is formed into several segments arranged sequentially in the height direction, wherein each segment includes a straight wall segment and a tapered segment connected thereto; wherein each set of tapered dies includes a tapered punch and a tapered die, wherein the tapered punch is used for the outer wall of the current pass forming part and the tapered die for the inner wall both include a straight wall portion and a tapered portion;

[0021] A shaping mold is used to shape the side wall of a blank tank, forming a tank body with a straight upper wall and a conical wall with a target taper in the remaining part; the shaping mold includes a shaping punch and a shaping die, both of which include a shaping straight wall part and a shaping conical part, and the taper angle of the shaping conical part is set to the target taper.

[0022] Furthermore, in the mold described in this invention, the tapered mold comprises at least three sets.

[0023] Furthermore, in the mold described in this invention, in each set of tapered molds, the tapered portion of the outer wall of the tapered punch for the current forming section and the tapered portion of the inner wall of the tapered die have the same taper angle.

[0024] Furthermore, in the mold described in this invention, when the tapered mold is provided in three sets, the tapered angle of the tapered portion of the tapered punch and tapered die used in the first tapered process is 2.5-3°; the tapered angle of the tapered portion of the tapered punch and tapered die used in the second tapered process is 3-4°; and the tapered angle of the tapered portion of the tapered punch and tapered die used in the third tapered process is 3-4°.

[0025] Furthermore, in the mold described in this invention, the height of the straight-walled shaping portion is 7.0-7.4 mm.

[0026] The manufacturing method of the conical can described in this invention can effectively eliminate can wall wrinkles and transition marks, thereby obtaining conical can products with excellent appearance quality.

[0027] The manufacturing method and mold described in this invention adopt a segmented tapered process, which reduces the gap between the inner and outer punches and dies during each stretching process, thereby reducing the impact of the difference in the upper and lower can diameters on the gap between the inner and outer dies. The punches and dies adopt the same cone angle and fit with the blank can separately during forming, which can eliminate possible micro-wrinkles. The combination of straight wall sections and tapered sections of the same height is conducive to more uniform deformation during subsequent shaping, avoiding transition marks on the can wall due to severe local deformation. Attached Figure Description

[0028] Figure 1 A schematic diagram of the structure of a finished two-piece conical can is shown.

[0029] Figure 2 The process of forming the taper of the conical can in this invention is illustrated schematically.

[0030] Figure 3 The diagram schematically illustrates the overall flow chart of the manufacturing method described in one embodiment of the present invention.

[0031] Figure 4 The diagram schematically shows the mold for the first tapered process in one embodiment of the manufacturing method described in this invention.

[0032] Figure 5 The diagram schematically shows a blank formed after the first tapered process in one embodiment of the manufacturing method described in this invention.

[0033] Figure 6 The diagram schematically shows a mold for the second-pass tapering process of the manufacturing method described in this invention in one embodiment.

[0034] Figure 7 The diagram schematically shows a blank formed after the second tapered process in one embodiment of the manufacturing method described in this invention.

[0035] Figure 8 The diagram schematically shows a mold for the third tapered process in one embodiment of the manufacturing method described in this invention.

[0036] Figure 9 The diagram schematically shows a blank formed after the third tapered process in one embodiment of the manufacturing method described in this invention.

[0037] Figure 10 The diagram schematically illustrates a state of the mold during the shaping process in one embodiment of the manufacturing method described in this invention.

[0038] Figure 11 The diagram schematically illustrates another state of the mold during the shaping process in one embodiment of the manufacturing method described in this invention.

[0039] Figure 12 for Figure 11 A magnified view of a portion of point A in the middle.

[0040] Figure 13 The diagram schematically shows a shaped tank according to one embodiment of the manufacturing method described in this invention.

[0041] Figure 14 The diagram schematically shows a can body after the can opening is enlarged according to one embodiment of the manufacturing method described in this invention.

[0042] Figure 15The diagram schematically shows a can body after the bottom of the can is formed according to one embodiment of the manufacturing method described in this invention. Detailed Implementation

[0043] The manufacturing method of the conical tank of the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, such explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0044] Figure 1 A schematic diagram of the structure of a finished two-piece conical can is shown.

[0045] like Figure 1 As shown, the tank body P is conical, meaning it has a large opening diameter and a small bottom diameter. Because it can be stacked, this reduces the transportation cost of empty tanks. However, such conical tanks, especially those with greater height, are prone to developing wall wrinkles during the forming process.

[0046] To address the aforementioned problems, the present invention provides a method for manufacturing a conical can in one embodiment, such as... Figure 2 and Figure 3 As shown, it may include the following steps:

[0047] For the blank tank P1 obtained by cupping 100 and stretching 201, 202, a multi-pass tapering process 301-303 is used to form a tapered blank tank P2 with several segments arranged sequentially in the height direction on the side wall of the blank tank. Each segment includes a straight wall segment connected to a tapered segment. The side wall of the tapered blank tank P2 is shaped 400 to form a tank body P3 with a straight wall at the top and a tapered wall with the target taper in the rest. The tank mouth is expanded 500 and the tank bottom is formed 600 to obtain the target tapered tank.

[0048] In some more specific embodiments, the tapering process is performed in three passes, correspondingly using three sets of tapering dies. The following will use this embodiment as an example to provide a detailed description of the manufacturing method and dies for the conical can:

[0049] Step S1: The raw material plate is blanked, punched, and stretched to obtain a circular blank container 13 with a diameter of D0 and a height of H0.

[0050] Step S2: As Figure 4 As shown, the outer wall of the first tapered punch 11 and the inner wall of the first tapered die 14 in the first tapering process both have straight wall portions and tapered portions. The tapered portions of the first tapered punch 11 and the first tapered die 14 have the same taper angle A1. In some preferred embodiments, to better avoid the formation of can wall wrinkles, the taper angle A1 can be 2.5-3°. The upper part of the first tapered punch 1 is sloped to facilitate subsequent can bottom forming.

[0051] During the tapering process, the first tapering die 14 is fixed, and a blanking force is applied by the first blanking die 12. The circular blank 13 with a diameter of D0 moves downward together with the first tapering punch 11 until the circular blank 13 fits against the tapered portions of the first tapering punch 11 and the first tapering die 14, forming a shape like... Figure 5 The first step shown has a height of H1, and the upper part of the first step is still a circular tank wall with a diameter of D0. The first step consists of a first straight wall section 131 with a height of H11 and a diameter of D1, and a first conical section 132 with a height of H12 and a cone angle of A1.

[0052] In some preferred embodiments, in order to make the deformation of the tank wall more uniform during subsequent shaping, H11 / H12 is preferably 0.9-1.1.

[0053] Step S3: As Figure 6 As shown, during the second tapering process, the outer wall of the second tapering punch 21 has a structure consisting of two sections of straight wall and a tapered section. The first section retains the shape of the first tapering punch 11 from the first tapering process, while the straight wall and tapered section of the second section are the parts of the second tapering punch used for forming in the current pass. The inner wall of the second tapering die 24 also includes a straight wall and a tapered section. The tapered section of the second section of the second tapering punch 21 and the tapered section of the second tapering die 24 have the same taper angle A2. In some preferred embodiments, to better avoid the formation of can wall wrinkles, the taper angle A2 can be 3-4°.

[0054] Similar to the first-pass tapering process, the intermediate-state blank 23 moves downward with the second tapering punch 21 until it comes into contact with the tapered portion of the second section of the second tapering punch 21 and the tapered portion of the second tapering die 24, forming a shape as shown in the image. Figure 7 The second step shown has a height of H2. This second step includes a second straight-walled section 231 with a height of H21 and a diameter of D2, and a second tapered section 232 with a height of H22 and a cone angle of A2. In some more preferred embodiments, the height H21 / H22 = 0.9 to 1.1.

[0055] Furthermore, in some preferred embodiments, since the end of the first tapering process includes a bevel for forming the bottom of the can, in order to prevent wrinkles, the height H1 of the first step is preferably less than the height H2 of the second step.

[0056] Step S4: As Figure 8As shown, during the third tapering process, the outer wall of the third tapering punch 31 comprises a structure with three straight-walled sections plus a tapered section. Two of these sections retain the shape of the punch used in the first and second tapering processes. The straight-walled and tapered sections of the third section are the parts of the third tapering punch used for forming in the current pass. The inner wall of the third tapering die 34 also has a structure with straight-walled and tapered sections. The tapered section of the third tapering punch 31 and the tapered section of the third tapering die 34 have the same taper angle A3. In some more preferred embodiments, to better avoid the formation of can wall wrinkles, the taper angle A3 can be 3-4°.

[0057] Similar to the first two tapered passes, the second intermediate state blank 33 moves downward with the third tapered punch 31 until it comes into contact with the tapered portion of the third section of the third tapered punch 31 and the tapered portion of the third tapered die 34, forming a shape as shown in the image. Figure 9 The third step shown has a height of H3. This third step comprises a third straight-walled section 331 with a height of H31 and a diameter of D3, and a third conical section 332 with a height of H32 and a cone angle of A3. In some preferred embodiments, the height H31 / H32 = 0.9 to 1.1. In some embodiments, H3 may be equal to H2.

[0058] Step S5: As Figure 10 , Figure 11 and Figure 12 As shown, during the shaping stage, the outer wall end of the shaping punch 41 is connected to the inclined surface as the shaping straight wall part, and its connection angle is A0 as the shaping conical part. Correspondingly, the upper part of the shaping die 44 is the shaping conical part with a cone angle of A0, and the lower part is the shaping straight wall part.

[0059] In some preferred embodiments, since some of the can wall material will flow to the bottom of the can during the bottom forming process, in order to ensure that the finished can wall is fully conical, the forming punch and forming die retain a straight wall portion with a height of H41, which ranges from 7.0 to 7.4 mm.

[0060] During can wall shaping, the shaping die 44 is fixed, and the blank can 43 to be shaped is placed between the shaping die 44 and the shaping punch 41. The shaping punch 41 moves downward until the blank can 14 to be shaped fits against the shaping cone portion of the shaping punch 41 and the shaping cone portion of the shaping die 44, forming a shape as shown in the figure. Figure 13 The tank shown has a straight upper wall and a conical wall with a target taper A0. For example... Figure 13 As shown, the bottom diameter of the tank is Db, which is less than D1; the taper is A0, which is less than A1 to A3; and the total height is H4.

[0061] Step S6: As Figure 14 As shown, the can opening is flared to form a straight-walled section with a diameter of Dt and a can height of H5.

[0062] Step S7: As Figure 15 As shown, the bottom of the tank is formed into an arch, and the original straight wall section disappears as it flows towards the bottom of the tank. The diameter of the end of the finished tapered tube near the bottom of the tank is Db, the diameter of the tank opening is Dt, the taper of the tapered section is the target taper A0, and the tank height is H6.

[0063] In a specific example, the finished conical can produced using the above manufacturing method and mold has a can height of 215 mm, a can wall taper of 2°, a can wall diameter near the bottom of 94.7 mm, and a can mouth diameter of 110 mm. It is made from a coated iron substrate with a coating thickness of 0.20-0.30 mm and a substrate temper of T2.5-T3.

[0064] First, the coated iron sheet is blanked into a round piece with a diameter of about 324mm. It is then stamped into a shallow cup with a diameter of 240mm. After a second stretching, it is formed into a can with a diameter of about 180mm. After a third stretching, it is formed into a round blank can 13 with a diameter of 150mm and a height of about 145mm.

[0065] Then, the first tapering process is performed. The taper angle A1 of the outer wall of the first tapering punch 11 and the tapered portion of the first tapering die 14 is 2.94°. The first tapering process forms a first step (i.e., the sub-segment formed in the current pass) with a height of H1 = 65 mm. The first step includes a straight wall section and a tapered section. The height of the straight wall section is H11 = 32.5 mm, and the diameter is D1 = 96.25 mm; the height of the tapered section is H12 = 32.5 mm, and the taper angle is A1 = 2.94°.

[0066] Next, the second tapering process is performed. The cone angle of the second section of the tapered portion of the second tapering punch 21 and the cone angle of the tapered portion of the second tapering die 24 are both A2 = 3.49°. The second tapering process forms a second step (i.e., the sub-segment formed in the current pass) with a height of H2 = 71 mm. The second step includes the straight wall section with a height of H21 = 35.5 mm and a diameter of D2 = 99.6 mm; the tapered section has a cone angle of A2 = 3.49° and a height of H22 = 35.5 mm.

[0067] Next, the third tapering process is performed. The cone angle of the third section of the tapered portion of the third tapering punch 31 and the cone angle of the tapered portion of the third tapering die 34 are both A3 = 3.47°. The third tapering process forms a third step (i.e., the sub-segment formed in the current pass) with a height of H3 = 71 mm. This third step includes a straight wall section and a tapered wall section. The height of the straight wall section is H31 = 35.5 mm, and the diameter is D3 = 103.93 mm; the height of the tapered section is H32 = 35.5 mm, and the cone angle is A3 = 3.47°. After the third tapering process, the total height of the billet is 207 mm.

[0068] Then, shaping is performed. The end of the shaping punch 41 has a beveled surface forming a straight wall section, and the cone angle of its shaping tapered section is A0 = 2°. Correspondingly, the upper part of the shaping die 44 is a tapered section with a cone angle of A0, and the lower part is a straight wall section. Shaping forms a tapered tank wall with a straight wall section at the end. The height of the straight wall section is H41 = 7.2 mm, the diameter is Db = 94.7 mm, which is less than D1 = 96.25 mm; the taper is A0 = 2°, which is less than A1 to A3, and the total height is H4 = 207.48 mm.

[0069] Then, the mouth of the can is flared. After flaring, the diameter of the straight wall section near the bottom is Db = 94.7 mm, the cone angle of the conical section is A0 = 2°, the mouth diameter is Dt = 110 mm, and the height of the can is H5 = 221.6 mm.

[0070] Finally, the bottom of the tank is formed. After the bottom is formed, the diameter of the end near the bottom of the tank is Db = 94.7 mm, the diameter of the tank opening is Dt = 110 mm, the cone angle of the conical wall is A0 = 2°, and the height of the tank is H6 = 215 mm. The forming of the conical tank is now complete.

[0071] It should be noted that the raw material plate used in this invention is coated iron, and the coating layer can be PET, PE, or PP polymer materials. Alternatively, the raw material plate can also be chrome-plated, zinc- or tin-plated thin steel sheet, cold-rolled thin steel sheet, aluminum sheet, stainless steel sheet, heat-resistant steel sheet, or alloy steel sheet. Depending on the required material thickness and tempering, the tapering process can be increased to four or more times.

[0072] The manufacturing method and mold of the conical can described in this invention can effectively eliminate can wall wrinkles and transition marks, thereby obtaining conical can products with excellent appearance quality.

[0073] It should be noted that the prior art portion of the protection scope of this invention is not limited to the embodiments given in this application. All prior art that does not contradict the solution of this invention, including but not limited to prior patent documents, prior publications, prior public uses, etc., can be included in the protection scope of this invention.

[0074] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0075] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A method of manufacturing a conical tank, characterized by, The method comprises the steps of: forming the side wall of the blank can into a plurality of sub-sections arranged in sequence in the height direction by using a multi-pass tapering process, wherein each sub-section comprises a straight wall section and a tapered section connected thereto; shaping the side wall of the blank can to form a can body with a straight wall at the upper part and a tapered wall with a target taper at the remaining part; performing can mouth expanding and can bottom shaping to obtain a target tapered can.

2. The production method according to claim 1, wherein The multi-pass tapering process is at least a three-pass tapering process.

3. The production method according to claim 1, wherein In each pass of the tapering process, the tapering sections of the tapering male die and the tapering female die used have the same taper angle.

4. The production method according to claim 3, wherein When the side wall of the blank can is formed into three sub-sections arranged in sequence in the height direction by using a three-pass tapering process, the taper angle of the tapering sections of the tapering male die and the tapering female die used in the first pass of the tapering process is 2.5-3°; the taper angle of the tapering sections of the tapering male die and the tapering female die used in the second pass of the tapering process is 3-4°; and the taper angle of the tapering sections of the tapering male die and the tapering female die used in the third pass of the tapering process is 3-4°.

5. The production method according to claim 1, wherein For each sub-section, the ratio of the height of the straight wall section to the height of the tapered section is 0.9-1.

1.

6. The production method according to claim 1, wherein The height of the straight wall section formed in the first pass of the tapering process is smaller than the height of the straight wall section formed in each subsequent pass of the tapering process.

7. A mold for manufacturing a conical can, characterized by, The method comprises: a plurality of sets of tapering dies corresponding to the multi-pass tapering process, which form the side wall of the blank can into a plurality of sub-sections arranged in sequence in the height direction, wherein each sub-section comprises a straight wall section and a tapered section connected thereto; wherein each set of tapering dies comprises a tapering male die and a tapering female die, and the outer wall of the tapering male die and the inner wall of the tapering female die for the current pass of forming part each comprise a straight wall section and a tapered section; a shaping die, which is used to shape the side wall of the blank can to form a can body with a straight wall at the upper part and a tapered wall with a target taper at the remaining part; the shaping die comprises a shaping male die and a shaping female die, and the shaping male die and the shaping female die each comprise a shaping straight wall section and a shaping tapered section, and the taper angle of the shaping tapered section is set as the target taper.

8. The mold of claim 7, wherein, The tapering dies comprise at least three sets.

9. The mold of claim 7, wherein, In each set of tapering dies, the tapering section of the outer wall of the tapering male die for the current pass of forming part and the tapering section of the inner wall of the tapering female die have the same taper angle.

10. The mold of claim 7, wherein When the tapering dies are provided with three sets, the taper angle of the tapering sections of the tapering male die and the tapering female die used in the first pass of the tapering process is 2.5-3°; the taper angle of the tapering sections of the tapering male die and the tapering female die used in the second pass of the tapering process is 3-4°; the taper angle of the tapering sections of the tapering male die and the tapering female die used in the third pass of the tapering process is 3-4°.

11. The mold of claim 7, wherein The height of the shaping straight wall section is 7.0-7.4 mm.

Images