CN116021100B

CN116021100B - Machining method for machining precision small boss type molded parts by electric spark

Info

Publication number: CN116021100B
Application number: CN202310286220.4A
Authority: CN
Inventors: 杨兵; 崔育; 曾连全; 万有军; 邓仕平; 席振寰; 郭芝忠; 林岗
Original assignee: Chengdu Baoligen Chuangke Electronics Co ltd
Current assignee: Chengdu Baoligen Chuangke Electronics Co ltd
Priority date: 2023-03-23
Filing date: 2023-03-23
Publication date: 2023-06-20
Anticipated expiration: 2043-03-23
Also published as: CN116021100A

Abstract

The invention belongs to the technical field of electrode processing, and discloses a processing method for processing precision small boss molded parts by electric spark processing, which comprises the following steps: combining each molded part with a matching structure suitable for forming on a tool electrode according to the boss distribution mode of each molded part at the same molded part of the die so as to determine the total electric spark machining quantity required to be machined of the tool electrode, wherein the electric spark machining quantity takes rows, columns or areas as machining units; determining an electric machining gap, a height and an electrode hole number of a tool electrode for electric discharge machining, wherein the unit of the electrode hole number is consistent with the machining unit of the electric discharge machining number; and modeling an electrode three-dimensional model according to the determined machining gap, the determined height and the determined electrode hole number of the tool electrode. The invention can finish all the forming parts with bosses in the whole plastic mould by electric machining only by one tool electrode, thereby saving the tool electrode material and the manufacturing cost.

Description

Machining method for machining precision small boss type molded parts by electric spark

Technical Field

The invention belongs to the technical field of electrode machining, and particularly relates to a machining method for machining precision small boss molded parts by electric spark machining.

Background

In the plastic injection mould, there is a kind of high-speed communication connector plastic connector product applied to the CPU of the large-scale computer, there are very many irregularly shaped small through holes distributed on this kind of plastic connector product, the size and interval of the hole on different plastic connector products are different, these small hole size is generally between 0.2 mm-0.35 mm, the distance between holes is adjusted from original more than or equal to 0.4mm to between 0.18 mm-0.30 mm, there are rounded corners of R0.05mm on the interior angle of all holes, and these hole size and surface have strict requirements.

In the corresponding plastic injection mold, the molding part consists of an upper mold and a lower mold, the upper mold and the lower mold are respectively required to be separated into hundreds of individual molding parts with different lengths and widths, and small bosses with the spacing of less than 0.4mm, different numbers and the size of 0.2 mm-0.35 mm are distributed on the molding parts, so that the difficulty is increased in the aspect of processing and manufacturing the molding parts.

In the Chinese patent with the application number of 200910059266.2, an invention patent named as a method for processing a die with precise and fine characteristics by utilizing high-speed milling is disclosed, and the boss shape on a formed part can be directly processed, but the method is only suitable for processing the die formed part with the interval between bosses being more than or equal to 0.4 mm.

At present, the forming parts with the distance of less than 0.4mm between bosses can be only formed by forming electric spark machining, but the forming electric spark machining has high difficulty, the machined surface is provided with tiny pits, and the reverse inclination is easy to generate, so that the demolding can be seriously influenced for the products, and the planeness, the geometric dimension and the like of the products are influenced; because the maximum cross section size of the boss on the formed part is less than or equal to 0.35mm, the corresponding tool electrode upper electrode machining area needs to be split into two parts to finish electric spark machining of the same boss; in addition, different tool electrodes are corresponding to different molded parts in the upper die and the lower die, so that the electric spark machining of the molded parts in the whole die can be finished only by machining and manufacturing a plurality of different tool electrodes, the quality difference between the machined molded parts is large, and the requirements are hardly met; the tool electrodes are large in processing and manufacturing quantity, high in difficulty, long in time, high in cost and poor in quality control, so that the processing and manufacturing period of the whole formed part is prolonged, and the current requirements cannot be met.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for machining precision fine boss-like molded parts by electric spark machining, so as to realize that a plurality of different molded parts at the same molded part can be machined by one electrode tool.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

a processing method for machining precision small boss molded parts by electric spark comprises the following steps:

combining each molded part with a matching structure suitable for forming on a tool electrode according to the boss distribution mode of each molded part at the same molded part of the die so as to determine the total electric spark machining quantity required to be machined of the tool electrode, wherein the electric spark machining quantity takes rows, columns or areas as machining units;

determining an electric machining gap, a height and an electrode hole number of a tool electrode for electric discharge machining, wherein the unit of the electrode hole number is consistent with the machining unit of the electric discharge machining number;

modeling an electrode three-dimensional model matched with the tool electrode through three-dimensional software according to the determined electric machining gap, height and electrode hole number of the tool electrode, wherein the electrode three-dimensional model is provided with at least a clamping part;

processing an electrode tool corresponding to the electrode three-dimensional model;

and (5) carrying out electric machining on the boss on the molded part.

According to the technical scheme, the bosses of each molded part of the same molded part can be matched and combined according to the method, the combined arrangement structure can be concentrated on one electrode tool, so that the processing of all boss molded parts of the same molded part of a die can be completed by the same electrode tool, the material and manufacturing cost of tool electrodes are saved, and if the die is provided with a plurality of molded parts and the boss structures are the same, a plurality of the same electrode tools can be processed at one time, and the die is more convenient and practical, such as an upper die and a lower die with the same boss structures.

In a possible implementation manner, the boss distribution mode of each molding part of the molding part is in a row distribution mode, each molding part is provided with at least one row of bosses, the shape of each boss is consistent, and the distance between two adjacent bosses in each row is equal; the unit of the electric spark machining quantity is a column;

combining each of the molded parts in a mating configuration adapted to be formed on a tool electrode, comprising the steps of:

selecting a first formed part, and selecting a formed part with the longest length and the largest number of bosses from formed parts with different lengths and widths of the same formed part as a first electric machining object;

matching and combining the formed parts, namely matching and combining all the formed parts with the bosses of at least one formed part in the length direction by taking the first formed part as a reference, and forming a plurality of rows of formed parts after matching and combining, wherein each boss of each row of formed parts needs to be aligned in the length direction and the interval is kept consistent, and the number of bosses of the longest row of formed parts in each row is smaller than or equal to the number of bosses of the longest row of formed parts in the first formed part;

and determining the number of electric spark machining, wherein the sum of the number of the boss rows on each row of molded parts of the same molded part is taken as the number of electric spark machining.

In a possible implementation, the calculation method for determining the number of electric discharge machining comprises the following steps:

the number of the molded parts is Qk, the number of boss rows is Ck, and the number of the molded parts to be electrosparked is tk=qk×ck, where k is a natural number of 1, 2, 3.

Respectively calculating the number of the electric spark machining to be formed on all the formed parts in the upper die;

calculating the total number of electric spark machining T in the upper die, t=t1+t2+t3+. TN, and calculating the total number of electric spark machining t=t1+t2+t3+. TN in the lower die;

and calculating the number of the formed parts which are recombined and combined according to the number of the parts and the number of the boss columns after being combined.

In a possible implementation, determining an electrical machining gap, a height and an electrode hole number of a tool electrode for electrical discharge machining comprises the steps of:

determining an electric machining gap of the tool electrode, and obtaining the electric machining gap through a formula S (F-0.09)/2, wherein S is the electric machining gap and is selected from 0.03mm to 0.10mm, F is the minimum distance between bosses on the formed part, and 0.09mm is the minimum thickness between electrode holes on the tool electrode.

Determining the height of a tool electrode, determining the diameter of a circled drill bit according to the formula D (W+S) -0.06, and determining the drilling depth according to the diameter of the drill bit, wherein D is the diameter of the drill bit, W is the maximum cross-section width of a boss on a formed part, 0.06mm is the allowance of an electrode hole on the tool electrode after drilling, and S is an electric machining gap;

The tool electrode upper electrode Kong Lieshu is determined, and the tool electrode upper electrode Kong Lieshu is determined based on the total number of spark machining and the number of spark machining tools for which all the formed parts are completed.

In a possible implementation manner, in determining the tool electrode upper electrode Kong Lieshu, the tool electrode has a number of times of use of the degradable surface, where G is the number of times of use of the degradable surface, H is the height of the tool electrode, and H is the height of the boss on the molded part, which can be found by calculating the formula g= (H-2)/H.

Thus, by determining the number of motor hole rows on the tool electrode based on the number of times the tool electrode is used to lower the surface, the electrode Kong Lieshu that can be used easily can be obtained.

In a possible implementation manner, after the number of times of using the degradable surface is included in the determination of the number of electrode hole columns on the tool electrode, the calculation formula of the number of electrode hole columns on the single tool electrode is as follows: n= [ [ T/(g+1) ]/B/2] +3×c or n= [ [ T/(g+1) ]/B/2] +3×c;

wherein, T and T in the formula select the largest one according to the calculation result of the calculation method for determining the number of electric spark machining, B is the number of tool electrodes, B is 2 or 4, C is the number of boss columns on the selected first electric machining part, N is the number of calculation results of electrodes Kong Lieshu on a single tool electrode, and N is an even number.

In a possible implementation manner, the die is provided with two forming parts and is divided into an upper die and a lower die, wherein the upper die and the lower die are composed of a plurality of forming parts with a plurality of bosses, the boss spacing between the upper die and the lower die is smaller than 0.4mm, and the maximum cross section size of the bosses on the forming parts is smaller than or equal to 0.35mm.

The upper die and the lower die are respectively processed by at least one tool electrode.

In a possible implementation manner, modeling the electrode three-dimensional model includes the following steps:

a first curved surface feature is created by adopting a curved surface stretching method, the feature shape is consistent with the boss, and the feature height is equal to the drilling depth of the optimized drill bit;

the curved surface features are arrayed along the length direction of the formed part to form a first row of curved surface features with the same number and distance as the bosses;

arranging the first row of curved surface features along the width direction of the formed part in an array manner, wherein the distance between the boss rows is equal, the number of the curved surface features is N, and the number of the curved surface features is equal to the number of electrode hole rows on a single tool electrode;

a symmetrical square reference outer frame which wraps the curved surface features in the middle is created by adopting a solid stretching method according to the symmetry center of the whole curved surface features, and the height of the symmetrical square reference outer frame is equal to the height of the curved surface features;

The method comprises the steps of taking a modeling reference plane on a square reference outer frame as a reference, and adopting a solid stretching method to establish a clamping part of a tool electrode which is connected with the square reference outer frame and has the length of more than or equal to 60.0mm, the width of 15.0mm and the height of the tool electrode as well as 3 locking threaded through holes of M4.0mm and chamfering in the direction of C2.0 mm;

and removing the curved surface feature inner side material in the square reference outer frame by adopting a curved surface materialization method, wherein the through holes formed on the square reference outer frame after the removal are electrode holes.

In a possible implementation manner, after the electrode three-dimensional model is molded, all the molded parts are assembled with the tool electrode, and the assembling method comprises the following steps:

in three-dimensional software, the forming parts of the upper die and the lower die are respectively assembled on the corresponding sides of the electrode three-dimensional model, and the electric machining position sizes of the forming parts and the tool electrode on an electric machining machine tool during electric spark electric machining are marked.

In a possible implementation manner, in three-dimensional software, the forming parts of the upper die and the lower die are respectively assembled on corresponding sides of the electrode three-dimensional model, and the electric machining position sizes of the forming parts and the tool electrode on an electric machining machine tool during electric spark electric machining are marked, and the method comprises the following steps:

Taking a molded part as a first processing object as a reference and taking two planes and electrode holes in the height direction on a tool electrode as references, assembling all molded parts in a mold on the tool electrode, assembling the molded part in an upper mold on one side of one plane on the tool electrode, assembling the molded part in a lower mold on one side of the other plane, wherein the appearance of the assembled molded part needs to be parallel to the appearance of the reference part, the boss needs to be overlapped with the electrode holes, and the bottom surface of the boss needs to be overlapped with the two plane references in the height direction of the tool electrode respectively;

the relative position size X, Y, Z between the tool electrode and each of the formed parts, that is, the electric machining position size of the formed parts and the tool electrode on the electric machining machine tool in the electric spark electric machining process, is marked by the center of the tool electrode and the reference surface respectively by the reference surface on the formed parts.

In a possible implementation manner, the electrode three-dimensional model is further provided with a square reference outer frame positioned at the periphery of the electrode hole area and at least one locking threaded through hole arranged on the clamping part;

after all the formed parts are assembled with the tool electrode, modeling of a tool electrode auxiliary model is further included, and the modeling method of the tool electrode auxiliary model comprises the following steps:

The method comprises the steps of respectively thickening the other sides except one side of a clamping part in the circumferential direction of a square reference outer frame of the electrode three-dimensional model, and respectively creating at least one connecting threaded through hole and at least one positioning connecting hole on the thickened physical characteristics to form a tool electrode auxiliary model comprising the electrode three-dimensional model.

In a possible implementation manner, in the modeling method of the tool electrode auxiliary model, the three remaining sides on the square reference outer frame are thickened by 10.0mm, and 6M 4 connecting threaded through holes and 3 ⌀ 3.000.000 fine positioning pin holes with the tolerance of +0.005mm to +0.01mm are respectively created on the three thickened physical features.

In a possible implementation, an electrode tool corresponding to the electrode three-dimensional model is processed, comprising the steps of:

selecting at least two electrode blanks, blanking each electrode blank by a milling machine, and roughly machining the appearance, the clamping part and the locking threaded through hole of the auxiliary model of the tool electrode;

finish machining is carried out on each electrode blank by a grinding machine, and each surface plane on the auxiliary model of the tool electrode is machined, wherein the parallelism and the flatness of the surface planes respectively corresponding to the machining of the upper die and the lower die forming part are controlled within 0.002 mm;

After finish machining, further machining each electrode blank through a high-speed machining center, and machining wire-out cutting wire-through holes, connecting threaded through holes and finish positioning connecting holes at positions corresponding to all electrode holes on the tool electrode auxiliary model;

overlapping and assembling the two electrode blanks by using a positioning connecting piece, ensuring that wire cutting wire penetrating holes of each electrode blank are aligned, and connecting and fixing by using a fastening connecting piece smaller than the overlapping height;

the two electrode blanks after the superposition and assembly are finished by linear cutting once, all electrode holes of the two electrode blanks are firstly processed, thickened parts, positioning connecting pieces and fastening connecting pieces are removed along a square reference outer frame, and a plurality of tool electrodes are formed after the linear cutting is finished;

and detecting the machined tool electrode, and then using the machined tool electrode after detection.

In a possible implementation, the electrical machining of the boss on the molded part is performed, comprising the steps of:

clamping the tool electrode on a reversible clamping head of an electric machining machine tool, correcting, and installing a to-be-machined formed part in a matched mode according to the electric machining position size of the tool electrode and the formed part through a group of fixing pieces;

And setting a machining operation program of an electric machining machine tool, starting machining, performing electric spark preprocessing on one of the formed parts with the longest length and the largest number of bosses serving as a first electric machining object, detecting the formed part after the electric spark preprocessing is finished, and sequentially machining the bosses of the rest formed parts through replacement after the detection is qualified.

In a possible implementation manner, the to-be-machined molded part is installed according to the size matching between the tool electrode and the electric machining position of the molded part through a set of fixing pieces, and the method comprises the following steps:

preparing three rectangular jacking blocks with avoidance positions, wherein the height of the rectangular jacking blocks is not lower than two thirds of the height of a formed part, two jacking blocks are respectively arranged on a magnetic table top of an electric machining machine, and the inner side surfaces of the two jacking blocks are respectively used as X and Y directional position references of all formed parts on the magnetic table top of the electric machining machine;

the first top block is placed at a proper position of the magnetic table top and is parallel to the X axis of the machine tool, the second top block is placed on the magnetic table top and is close to the left lower corner of the first top block, the second top block is parallel to the Y axis of the machine tool, the parallelism and the verticality of the two top blocks are controlled within 0.002mm by using a dial indicator, and after the two top blocks are arranged, a small amount of 502 glue is used for fixing the two top blocks and the magnetic table top to prevent loosening;

Determining an initial position between the center of the machine head and the inner side surfaces of the two jacking blocks by using a ball probe;

according to the assembly position relation between the tool electrode and the first electric machining part, the first electric machining part is placed on the magnetic table top, two side surfaces on the first electric machining part are respectively attached to the inner side surfaces on the fixed top blocks on the magnetic table, and the first electric machining part is pressed by the remaining top blocks to prevent the first electric machining part from loosening.

In a possible embodiment, a machining operation program of an electric machining machine tool is set, machining is started, one of the formed parts, which has the longest length and the largest number of bosses, is used as a first electric machining object to perform electric spark pre-machining, after the electric spark pre-machining is completed, the electric spark pre-machining is detected, and after the electric spark pre-machining is qualified, bosses of each of the remaining formed parts are sequentially machined through replacement, and the method comprises the following steps:

when the first electric machining forming part is machined by electric spark, three sections of electric machining programs need to be written and circular translation is adopted; in the first section of electric machining program, respectively roughing a boss on a first electric machining part by using electrode holes in a 1 st area and a 2 nd area, and carrying out electric machining to Ra0.8um, wherein the allowance is 0.02mm;

In the second section of electric machining program, the boss is finished by using the electrode hole in the 3 rd area, electric machining is carried out until Ra0.4um is reserved, the allowance is 0.01mm, after the second section of electric machining program is finished, the first electric machining forming part on the magnetic table top 3 is taken down to carry out boss size measurement and surface roughness measurement, and electric machining parameter optimization adjustment is carried out according to the actually measured allowance and roughness;

finally, the third section of electric machining program and the electrode Kong Jingxiu boss in the 4 th area are used for adjusting the size to 0.000 to +0.003mm, the surface roughness to Ra0.2um and the sharp angle of the boss root to R0.03max; and taking down the formed part again to detect whether the formed part is qualified or not, and if the formed part is unqualified, continuing to optimally adjust the electric machining parameters, and continuing to finish until the formed part is qualified.

In a possible implementation manner, after the electric spark preprocessing is finished, in the process of performing formal electric machining, the three-section electric machining program can be executed at one time, the formed part does not need to be taken down for inspection during the second section program, the formed part is taken down for detection until the three-section electric machining program is executed, no problem exists under normal conditions, and if the formed part is unqualified, the formed part needs to be trimmed once again; every time a new machined part is started, a new electrode Kong Lieshu corresponding to 1 area needs to be added, each formed part needs to ensure electrode holes with 4 areas, and the third procedure needs to use the new electrode holes after the addition.

In a possible implementation mode, after the electrode hole on the tool electrode is used up, a special tool connected with the head of the forming electric spark machine tool and provided with the tool electrode is taken down, the tool electrode is subjected to first surface lowering processing according to the height of a boss on a formed part through wire cutting, a galvanized wire of ⌀ 0.25.25 mm is selected, a processing technology of rough cutting once and finishing four times is adopted, the allowance of the first rough cutting is 0.04mm, the allowance of the second fine cutting is 0.01mm, the allowance of the third fine finishing is 0.003mm, the fourth fine finishing is performed, and the surface is controlled within Ra0.25 um; after the surface is lowered, the special fixture with the tool electrode is connected with the machine tool head again, the electric discharge machining can be directly carried out on the boss on the formed part, after the electrode hole is used, the second surface lowering machining is carried out by the same method, the height of the tool electrode is more than or equal to 2mm after the surface lowering of the last time is required to be ensured, and the deformation of the tool electrode after the surface lowering is prevented.

In a possible implementation manner, in the process of carrying out the electro-machining of the boss on the molded part, a method for using a tool electrode is further included, and the method for using includes the following steps:

the tool electrode is driven by a machine head of the electric machining machine tool to move, and each formed part is sequentially machined in a multi-region mode according to the machining direction from one side to the other side, wherein the multi-region comprises three functional regions which are the same as the number of boss columns of the machined formed part, and the three functional regions are sequentially divided into a rough machining region, a finish machining region and a finish machining region along the machining direction.

Compared with the prior art, the invention has the following beneficial effects:

1. all the forming parts with bosses in the whole plastic mold can be electrically machined by only one tool electrode, so that the tool electrode material and the manufacturing cost are saved.

2. The high-speed machining center is utilized, and the hard alloy drill bit is adopted, so that the machining problem of wire cutting of wire through holes of electrode holes smaller than ⌀ - ⌀ 0.35.35 mm on a tool electrode is solved.

3. The plurality of tool electrodes can be processed at one time by superposing the plurality of tool electrodes, the electrode hole size and the electrode hole surface roughness on each tool electrode are the same, the surface roughness of the electrode hole can reach Ra0.25, and the wire cutting device plays a key role in forming tiny pits on the electric spark control surface; the quality of the tool electrode is well ensured, and the very high wire cutting processing cost is saved.

4. The used tool electrode can be reused after the worn part is subjected to face-down removal processing, so that the number of the tool electrode is reduced; saving tool electrode materials and manufacturing cost.

5. In the electric spark machining process, the tool electrodes do not need to be frequently replaced and the electric machining parameters are not required to be adjusted, the consistency of the boss sizes and the surface roughness on all molded parts is ensured, the qualification rate is more than 97%, the fine pits, the anticlockwise inclination, the geometric dimension and the flatness of the boss surfaces after electric machining are controlled in an acceptable range, and the mold passes the acceptance of plastic products after injection molding.

6. The invention can be widely applied to similar forming parts in a high-speed communication connector mould.

Drawings

FIG. 1 is a schematic view of a three-dimensional model of an upper mold of a mold according to an embodiment of the present application;

FIG. 2 is a schematic view of a three-dimensional model of a lower mold of a mold according to an embodiment of the present application;

FIG. 3 is a schematic view of a boss structure of a partially formed part according to an embodiment of the present application;

FIG. 4 is a schematic view of a molded part with different length, width, and number of bosses in a mold according to an embodiment of the present application;

fig. 5 is a schematic diagram of matching and combining molded parts according to an embodiment of the present application, where (C) is a front view and a top view of a first electro-formed part, and (D) and (E) are front views and top views of partially matched and combined molded parts;

FIG. 6 is a schematic diagram of a first step of an electrode three-dimensional model modeling sequence for a tool electrode according to an embodiment of the present application;

FIG. 7 is a second step schematic illustration of an electrode three-dimensional model modeling sequence for a tool electrode according to an embodiment of the present application;

FIG. 8 is a third step schematic diagram of an electrode three-dimensional model modeling sequence for a tool electrode according to an embodiment of the present application;

FIG. 9 is a fourth step schematic diagram of an electrode three-dimensional model modeling sequence for a tool electrode according to an embodiment of the present application;

FIG. 10 is a fifth step schematic diagram of an electrode three-dimensional model modeling sequence for a tool electrode according to an embodiment of the present application;

FIG. 11 is a schematic view of the positional relationship between the molded part and the tool electrode in the upper and lower molds in part of the embodiment of the present application;

FIG. 12A is a top view of a molded part and tool electrode according to an embodiment of the present application;

FIG. 12B is a front view of a molded part and tool electrode according to an embodiment of the present application;

FIG. 12C is a side view of a molded part and tool electrode according to an embodiment of the present application;

FIG. 12D is a partial view of a molded part and tool electrode according to an embodiment of the present application;

FIG. 13 is a diagram illustrating a clamping assembly of a tool electrode auxiliary model and a dedicated jig according to an embodiment of the present application;

FIG. 14 is an exploded view of a tool electrode auxiliary model and a dedicated jig according to an embodiment of the present application;

FIG. 15 is an enlarged partial schematic view of a wire cut through hole to be drilled in a high speed machining center according to an embodiment of the present application;

FIG. 16 is a diagram of a multi-piece assembly stack assembly of a tool electrode auxiliary model in accordance with an embodiment of the present application;

FIG. 17 is an exploded view of a tool electrode auxiliary model assembly according to an embodiment of the present application;

FIG. 18 is a diagram illustrating a tool electrode and flip chuck connection assembly according to an embodiment of the present application;

FIG. 19 is an exploded view of a tool electrode and flip chuck according to an embodiment of the present application;

FIG. 20 is a diagram showing a combination of a turnover chuck with a tool electrode connected and a dedicated jig according to an embodiment of the present application;

FIG. 21 is an exploded view of a flip chuck with a dedicated fixture attached to a tool electrode according to an embodiment of the present application;

FIG. 22 is a combined view of the electric discharge machining state of the forming machine according to the embodiment of the present application;

FIG. 23 is an exploded view of the electric discharge machine according to the embodiment of the present application;

fig. 24 is a schematic view of tool electrode drop in accordance with an embodiment of the present application.

In the figure: 1-a boss bottom surface; 2-a boss; 3-first forming part; 4-a first composite molded part; 5-a second composite molded part; 6-first row of bosses; 7-a first curved feature; 8-a first column of curved features; 9-multiple columns of curved surface features; 10-square reference frame; 11-X is towards a central reference plane; 12-modeling a reference plane; 13, clamping part; 14-locking the threaded through hole; 15-chamfering in the direction; 16-electrode holes; 17-a tool electrode; 18-a first Z reference plane; 181-a second Z reference plane; 19-Y direction reference plane; 20-a first X-direction reference plane; 201-a second X-direction reference plane; 21-tool electrode auxiliary model; 22-pin through holes; 23-connecting threaded through holes; 24-a first socket head cap screw; 25-pins; 26-an internal hexagonal headless screw; 27-dividing lines; 28-a reversible chuck; 29-a second socket head cap screw; 30-a special jig; 31-a third socket head cap screw; 32-mating reference plane; 33-magnetic table plane; 34-a first top block, 35-a second top block, 36-a third top block; 37-first landing tool electrode position; 38-second step down tool electrode position; 351—top block X-direction reference plane; 341-top block Y-reference plane; 352-X direction datum plane of the molded part; 342—forming a part Y-reference plane; 331-forming a part Z-reference plane; 301-first column electrode holes; 302-a first plurality of rows of electrode holes; 303-a second plurality of rows of electrode holes; 304-a third plurality of rows of electrode holes; 305-fourth multiple columns of electrode holes; 90-threading holes; 500-machine head.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

The invention is further described with reference to the drawings and specific examples.

The embodiment of the application provides a machining method for machining precision fine boss type molded parts by electric spark machining, which can be used for machining molded parts with precision fine bosses, is preferably suitable for machining molded parts with boss spacing smaller than 0.4mm and boss maximum cross-section size smaller than or equal to 0.35mm, and can be used for machining bosses outside the range by adjusting some parameters without limitation.

Referring to fig. 1-4, a mold for a plastic connector of a high-speed communication connector applied to a cpu of a large computer is described below, wherein the mold has two molding portions, an upper mold and a lower mold, the upper mold and the lower mold have identical boss structures and are arranged in rows, so that an electrode tool can be used for processing, the minimum spacing of bosses on the molding parts of the mold is 0.215mm, the maximum cross-sectional width w=0.245 mm of the bosses, and the length of each molding part is different and the number of the molding parts is not identical.

Aiming at the processing of the formed part of the die, the processing method of the electric spark processing precision fine boss type formed part comprises the following steps:

step 1: a first electroformed part is selected.

As shown in fig. 1, 2 and 5, a first formed part 3, which is the first electrical object, is selected from the three-dimensional model of the mold to be the first formed part having the longest length and the largest number of bosses 2.

Step 2: and matching and combining the formed parts.

Referring to fig. 5, with the selected first forming part 3 as a reference, all forming parts with bosses 2 and different lengths and widths in the upper die and the lower die are matched and combined respectively, that is, another suitable forming part is spliced in the length direction of the forming part, the bosses 2 in the length direction after splicing need to be aligned, the distance needs to be kept consistent, and the number of the bosses 2 is less than or equal to the number of the bosses 2 in the length direction of the first forming part 3, such as the first combined forming part 4 and the second combined forming part 5.

Step 3: and determining the number of the electric spark machining.

In the embodiment of the application, the sum of the columns of the bosses 2 on all the formed parts is taken as the total electric spark machining quantity. As shown in fig. 5 (C), the first molded part 3 is arranged in the length direction by one boss 2 on the selected first molded part 3 to obtain a first row of bosses 6, and the first row of bosses 6 are arranged in the width direction to obtain a second row of bosses, i.e., two rows of bosses are shared on the selected first molded part 3; thus, if the number of molded parts is Qk and the number of boss rows is Ck, the number tk=qk×ck of the molded parts to be electrosparked (where k is a natural number of 1, 2, and 3).

Further, the numbers T1, T2 required to be electrically machined on the first and second molded parts in the upper die are calculated separately, t1=q1×c1=3×2=6 (column), t2=q2×c2=1×2=2 (column), and the numbers T1, T2 required to be electrically machined on the first and second molded parts in the lower die are calculated, t1=q1×c1=3×2=6 (column), t2=q2×c2=1×2=2 (column). The molded parts rearranged and combined in the above step 2 are calculated according to the number of parts after being combined and the number of columns of the bosses 2, as td=1×3=3 (columns) and te=1×6=6 (columns) in fig. 5 (D) and (E). In the calculation of the number of columns of T1 and T1 for the upper and lower dies, at least two more cases are required for the pre-processing, and therefore the number of molded parts is 3.

Further, the number of total electromachining in the upper die t=t1+t2+td+ Te. is calculated.

Further, the number of total electromachining in the lower die t=t1+t2+td+ te. is calculated.

Step 4: an electrical machining gap of the tool electrode is determined.

The minimum spacing between the bosses 2 on the above selected first molded part 3 is 0.215mm, and the machining gap is set to S, then S is required to be + (minimum spacing-0.09)/2= (0.215-0.09)/2=0.063 mm, preferably the machining gap s=0.05 mm. Wherein 0.09mm is the minimum thickness between electrode holes on the tool electrode.

Step 5: the height of the tool electrode is determined.

The height of the tool electrode may be determined based on the drilling depth of the selected drill bit, as shown in the table of machining parameters for the center hole cutter and drill bit. The maximum cross-sectional width w=0.245 mm of the boss 2 on the selected first molded part 3 is set to be D, the diameter D is equal to or smaller than (w+s) -0.06= (0.245+0.050) -0.06=0.235 mm, the diameter d= ⌀ 0.2.2 mm of the drill is preferable, the drilling depth of the drill is 4mm, and the height of the tool electrode is equal to 4mm. Wherein, 0.06mm is the allowance of the electrode hole on the tool electrode after drilling processing.

Step 6: an electrode Kong Lieshu on the single tool electrode is determined.

Firstly, determining the required count of tool electrodes according to the manufacturing cycle of parts in the whole die; if the period is very urgent, 4 tool electrodes 17 are needed to be considered, and the electric machining of all the molded parts is finished by four molding electric spark machine tools respectively, namely, two molding electric spark machine tools are used for electric machining of the molded parts in the upper die, two molding electric spark machine tools are used for electric machining of the molded parts in the lower die, and each molding electric spark machine tool corresponds to 1 tool electrode 17; under normal conditions, only 2 tool electrodes 17 are considered, namely 1 upper die and 1 lower die, and the electric machining of all parts is finished by two forming electric spark machine tools respectively; secondly, the number of times of using the tool electrode 17 by lowering the surface is calculated according to the height of the boss 2 and the height of the tool electrode 17, as shown in fig. 24, that is, the worn electrode hole 16 is partially removed for reuse after the tool electrode 17 is used, the height of the tool electrode 17 after lowering the surface cannot be less than or equal to 2.0mm, and the tool electrode 17 is prevented from being deformed.

The number of times of usage of the degradable surface is calculated as follows by a calculation formula: g= (H-2)/h= (4-2)/0.9≡2 (times); wherein, the height H=4.0 mm of the tool electrode, the height h=0.9 mm of the boss on the formed part, and the number of times of surface falling is 2.

The calculation formula of the electrode hole column number on the electrode of the single tool is as follows: n= [ [ T or T/(g+1) ]/B/2] +3×c= [ [ 138/(2+1) ]/2/2] +3×2=52 (columns); in the formula, T and T are selected according to the calculation result in the step 3, the maximum value t=138 columns, B is the number of tool electrodes 17, and the electric machining of all the formed parts is planned to be completed by two forming electric spark machine tools, so that the value of B is 2, and the upper electrode Kong Lieshu n=52 of a single tool electrode.

Step 7: tool electrode structure and three-dimensional modeling.

As shown in fig. 6 to 10, the tool electrode 17 includes an electrode hole 16, a square reference frame 10, a clamping part 13, a locking screw through hole 14, and a directional chamfer 15; three-dimensional modeling of the tool electrode 17 is performed using three-dimensional software Creo with reference to the first molded part 3.

The three-dimensional modeling method specifically comprises the following steps:

step 71: firstly, a first curved surface feature 7 is created by adopting a curved surface stretching method, the feature shape is the same as that of the boss 2, and the feature height is 4.0mm;

step 72: the first curved surface features 7 are arrayed along the length direction of the first forming part 3 to form first rows of curved surface features 8 with the same number and distance as the bosses 2;

Step 73: arranging a plurality of rows of curved surface features 9,N with equal distances between boss rows and N rows of the first row of curved surface features 8 along the width direction of the first forming part 3, and calculating in the step 6 to obtain N=52 rows;

step 74: a symmetrical square reference outer frame 10 which wraps the multi-column curved surface features 9 in the middle is created by adopting a physical stretching method according to the symmetry center of the whole multi-column curved surface features 9, and the height of the symmetrical square reference outer frame is equal to that of the first column curved surface features 8;

step 75: using a modeling reference plane 12 on the square reference outer frame 10 as a reference, and adopting a solid stretching method to create a clamping part 13 of a tool electrode 17 which is connected with the square reference outer frame 10 and has a length of 60.0mm, a width of 15.0mm and a height of the tool electrode, 3M 4.0mm locking threaded through holes 14 and a C2.0mm directional chamfer 15;

step 76: and removing materials on the inner sides of the rows of curved surface features 9 in the square reference outer frame 10 by adopting a curved surface materialization method, wherein through holes formed on the square reference outer frame 10 after the removal are electrode holes 16.

Since the electrode holes 16 are very many, the computer can cause operation jam and unsmooth operation when running the three-dimensional model of the tool electrode 17, and the working efficiency is affected, so the curved surface materialization method must be carried out in the last step of three-dimensional modeling.

Step 8: all the molded parts are assembled with the tool electrode.

As shown in fig. 11 and 12A, 12B, 12C and 12D, first, all the molded parts in the mold are assembled to the tool electrode 17 with the first molded part 3 as a reference and the first Z-direction reference plane 18, the second Z-direction reference plane 181 and the electrode hole 16 on the tool electrode 17 as references, the molded part in the upper mold is assembled on one side of the first Z-direction reference plane 18, the molded part in the lower mold is assembled on one side of the second Z-direction reference plane 181, the shape of the assembled molded part needs to be parallel to the shape of the first molded part 3, the boss needs to be overlapped with the electrode hole 16, and the boss bottom surface 1 needs to be overlapped with the first Z-direction reference plane 18 and the second Z-direction reference plane 181 on the tool electrode respectively; next, the relative position dimensions X, Y, Z between the tool electrode 17 and each of the molded parts, that is, the electrical machining position dimensions of the molded parts and the tool electrode 17 on the electrical machining machine during the electrical discharge machining, are marked with the first X-direction reference plane 20, the second X-direction reference plane 201, the X-direction center reference plane 11, the Y-direction reference plane 19, the first Z-direction reference plane 18, and the second Z-direction reference plane 181 on the tool electrode 17, respectively, with the molded part X-direction reference plane 352, the molded part Y-direction reference plane 342, and the molded part Z-direction reference plane 331 on the molded part.

Step 9: the tool electrode assists the model.

As shown in fig. 13 and 14, the tool electrode auxiliary model 21 is created by modeling again based on the electrode three-dimensional model of the tool electrode 17, specifically, the three sides of the square reference frame, that is, the Y-direction reference plane 19, the first X-direction reference plane 20 and the second X-direction reference plane 201, are thickened by 10.0mm, and 6M 4 connecting threaded through holes 23 and 3 ⌀ 3.000.000 mm pin through holes 22 for fine positioning are created on the three thickened physical features, respectively, with a tolerance of +0.005mm to +0.01 mm.

Step 10: the processing technology of the tool electrode comprises the following steps: the machining of the tool electrode 17 is completed by six working procedures of a milling machine, a grinding machine, a high-speed machining center, assembly, wire cutting (slow wire feeding) and detection in sequence.

The processing technology specifically comprises the following steps:

step 101: the tool electrode 17 is made of red copper, and is fed by a milling machine and rough-machined with the appearance of the tool electrode auxiliary model 21 and the three M4 locking threaded through holes 14 on the clamping part 13.

Step 102: the tool electrode is finished by a grinding machine to assist six planes on the model 21 and the direction chamfer 15, wherein the parallelism and the flatness of the first Z-direction reference plane 18 and the second Z-direction reference plane 181 need to be ensured to be within 0.002 mm.

Step 103: as shown in fig. 13 to 15, wire-cutting through holes 90, and 6M 4 connecting threaded through holes 23 and 3 pin through holes 22 for fine positioning ⌀ 3.000.000 mm are machined by a high-speed machining center at positions of all the electrode holes 16 on the tool electrode auxiliary model 21, respectively.

In this step, before the machining of the auxiliary tool electrode model 21, the high-speed machining center clamps the clamping part 13 on the auxiliary tool electrode model 21 with the special fixture, and uses the first socket head cap screws 24 of M4 to connect and lock the special fixture with the tool electrode auxiliary model 21 through the 3 locking threaded holes 23 on the clamping part 13, links the special fixture with the precise clamping system base on the high-speed machining center machine, determines the initial machining position according to the shape of the auxiliary tool electrode model 21, sets the center hole cutter and the drill bit, runs the high-speed machining center to start the execution program, after finishing the machining of the wire holes 90, needs to project the auxiliary tool electrode model 21 onto a piece of white paper in a lighting mode to check whether all the wire holes 90 completely penetrate or are missed, after determining that there is no problem, takes the auxiliary tool electrode model 21 from the special fixture, clamps the next auxiliary tool electrode model 21, and repeats the operation until finishing the machining of the procedure.

The wire-cut through hole 90 is specifically formed by drilling at a high-speed machining center; the drill bit was selected from a coated cemented carbide drill bit, the drill bit diameter d= ⌀ 0.2.2 mm was calculated in step 5, the center hole cutter was selected from a used ball end mill, the cutter diameter was selected as the drill bit diameter, reference was made to the table of machining parameters for the center hole cutter and drill bit, which table is as follows:

the high-speed machining center needs to pay special attention when drilling, because the plasticity of red copper is good and copper is difficult to discharge, the drill bit needs to be withdrawn once for discharging and cutting every time the drill bit is fed once, the drill bit is prevented from being broken by copper cutting blockage in a hole, and the service life of the drill bit can be controlled within 3 hours.

Step 104: as shown in fig. 16 and 17, the tool electrode auxiliary model 21 is assembled together by stacking with the pins 25, after stacking, the wire cutting threading holes 90 are required to be completely aligned, and then the connecting and fixing are performed by using the hexagon socket screw 26 of M4 smaller than the stacking height.

In this step, after the superimposed assembly of the auxiliary tool electrode pattern 21 is completed, it is also necessary to project the auxiliary tool electrode pattern 21 onto a piece of white paper by means of illumination to check whether all the wire holes 90 are completely aligned.

Step 105: the superimposed and assembled auxiliary tool electrode model 21 is finished by one-step wire cutting (slow wire feeding), firstly, all electrode holes 16 on the auxiliary tool electrode model 21 are finished, then the redundant auxiliary model is removed along a parting line 27 on the square reference outer frame 10 of the tool electrode, the auxiliary model is removed, meanwhile, the hexagon socket head screw 26 and the pin 25 are removed together, and after the wire cutting is finished, the removed tool electrode 17 is automatically separated into one piece.

In this step, before machining the electrode hole 16 in the auxiliary tool electrode model 21, the clamping part 13 on which the auxiliary tool electrode model 21 is stacked is fixed to a wire cutting machine, and a ⌀ 0.1.1 mm galvanized wire is selected to determine the initial machining position from the external shape of the auxiliary tool electrode model 21.

The wire cutting (slow wire feeding) is carried out on the electrode hole 16 by adopting a processing technology of rough cutting once and finishing four times, wherein the allowance of rough cutting is 0.03mm in the first time, the allowance of fine cutting is 0.01mm in the second time, the allowance of finishing is 0.003mm in the third time, the finishing is carried out in the fourth time, the tolerance of the electrode hole 16 is controlled within 0 to-0.005 mm, and the surface is controlled within Ra0.25 um.

Because the electrode holes 16 are very many, the hole surface and the size are required to be high, and the wire cutting time is long, before the electrode holes 16 are cut in a formal manner, one electrode hole 16 needs to be pre-machined to adjust the wire cutting parameters, and after the electrode holes 16 meet the requirements, all the electrode holes 16 are cut, and whether cutting abnormality exists or not needs to be observed in the cutting process.

Step 106: and (3) finishing the detection of the tool electrode, and protecting the tool electrode 17 qualified in detection and then sending the tool electrode to a forming electric spark for use.

Step 11: and finishing the electric machining of the boss on the molded part.

The electrical machining of the molded parts in the upper and lower dies is performed by several electrical machining tools according to the count of the tool electrodes 17.

The electric machining of the boss on the molded part specifically comprises the following steps:

step 111: as shown in fig. 18-21, the second socket head cap screws 29 of M4 are used to connect the tool electrode 17 with the reversible chuck 28, and then the reversible chuck is clamped onto two matching reference planes 32 of the special fixture 30 through the third socket head cap screws 31, and the tool electrode 17 is calibrated at 0.002 mm.

If the first tool electrode 17 is used for machining the molded part in the upper die, the next tool electrode 17 is clamped to be turned 180 degrees relative to the first tool electrode 17 and then clamped to the special jig 30 for machining the molded part in the lower die.

Step 112: as shown in fig. 22 and 23, three rectangular first, second and third top blocks 34, 35 and 36 with a height not lower than two thirds of the height of the molded part are prepared, the first and second top blocks 34, 35 are respectively arranged on a magnetic table plane 33 of the electric machine tool, and the inner side surfaces of the first and second top blocks 34, 35, namely a top block Y reference plane 341 and a top block X reference plane 351 are respectively used as the position references of all molded parts in the X and Y directions on the magnetic table plane 33 of the electric machine tool; the first top block 34 is placed at a proper position on the magnetic table plane 33 and is parallel to the X axis of the machine tool, the second top block 35 is placed on the magnetic table plane 33 and is close to the lower left corner of the first top block 34, the second top block is parallel to the Y axis of the machine tool, the parallelism and the perpendicularity of the two top blocks are controlled within 0.002mm by using a dial gauge, and after the first top block 34 and the second top block 35 are arranged, a small amount of 502 glue is used for fixing the first top block 34, the second top block 35 and the magnetic table plane 33 to prevent loosening.

Step 113: the initial position between the center of the machine head 500 and the inner surfaces of the first and second top blocks 34 and 35 is determined by a ball probe.

Step 114: as shown in fig. 12A, 12B, 12C, 22 and 23, according to the assembly positional relationship between the tool electrode 17 and the first molded part 3 in step 8, the first molded part 3 is placed on the magnetic table plane 33, the side surface 352 on the first molded part 3 is bonded to the top block X-direction reference plane 351 of the side surface of the second top block 35, the side surface 342 on the first molded part 3 is bonded to the top block Y-direction reference plane 341 of the side surface of the first top block 34, the bottom surface on the first molded part 3, i.e., the molded part Z-direction reference plane 331 is bonded to the magnetic table plane 33, and the first molded part 3 is pressed by the third top block 36 to prevent the first molded part 3 from loosening.

Step 115: as shown in fig. 20 to 23, the special jig 30 with the tool electrode 17 clamped is connected to the head 500 of an electric discharge machine, a machine tool program is set, and the running program starts the electric machining.

Because the electric spark machine tools are different in each type, the electric discharge parameters are also different, and the factors influencing the electric discharge parameters are also many, and a unified and stable parameter standard cannot be formed, when the boss 2 on the first formed part 3 with higher electric machining requirements is machined, the number of the formed parts needs to be considered more than 2, and the electric spark machine tools are used for adjusting the electric machining parameters in the electric spark pre-machining process;

Firstly, carrying out electric spark pre-machining on the boss 2 on the redundant first formed part 3, debugging relatively preferable electric machining parameters through electric spark pre-machining, detecting the first formed part 3 after electric spark pre-machining, and formally starting to finish electric spark machining on the boss 2 on the rest first formed part 3 after the requirements can be completely met; the rest of the formed parts do not need to pre-process electric sparks and debug electric machining parameters, and only the formed parts to be electrically machined are replaced according to the placement method of the first formed part 3 on the magnetic table plane 33, and attention is paid to the fact that the relative position sizes between the last formed part and the formed parts to be electrically machined in the process are required to be modified due to the fact that the appearance sizes of the formed parts are different.

Regarding the machining sequence of the molded parts, the electric machining sequence of the molded parts is that of the remaining molded parts except for the first molded part 3, the molded part having the longest length and the largest number of bosses is machined first, then the other single molded part is machined, and finally the combined molded parts are electrically machined again, as shown in fig. 5 (D) and (E).

In the method for using the tool electrode 17, as shown in fig. 12D, 22 and 23, the machine head 500 drives the tool electrode 17 to move rightward, and starts to use from the rightmost first row of electrode holes 301; in the actual electro-machining process, the number of the electrode holes used at present is possibly one or more, and mainly depends on the number of the bosses on the machined part; if the number of columns of bosses on the current machined part is L, then the electrode Kong Lieshu corresponding to one region is also L; because the tool electrode can generate loss in the electric machining process, in order to ensure the precision size and the surface quality of the boss, 4 electrode holes in areas are needed to finish the electric machining of a formed part; electrode hole-to-next electrode hole distance w=p×l for one region, P being the distance between one row of electrode holes to the next row of electrode holes, L being the electrode Kong Lieshu in one region.

The number of rows of bosses on the first molded part 3 is two, corresponding to two rows of first row electrode holes 301 in the region of the first plurality of rows of electrode holes 302 as in fig. 12D, the distance P between the first row electrode holes 301 and the next row of first row electrode holes 301 is 0.868mm, and the electrode Kong Lieshu L in the region is 2 rows, then w=p×l=0.868×2= 1.736mm, that is, the distance from the region of the first plurality of rows of electrode holes 302 to the region of the second plurality of rows of electrode holes 303 is 1.736mm, and the distance from the region of the second plurality of rows of electrode holes 303 to the region of the third plurality of rows of electrode holes 304 is 1.736mm.

When the first formed part 3 is pre-machined by the electric spark, three sections of electric machining programs need to be written and circular translation is adopted; in the first section of the electro-machining program, respectively roughing a boss on the first formed part 3 by using electrode holes of two rows of first row electrode holes 301 in the area of a first plurality of rows of electrode holes 302 and electrode holes of two rows of first row electrode holes 301 in the area of a second plurality of rows of electrode holes 303, and electro-machining to Ra0.8um, wherein the allowance is 0.02mm; in the second section of electric machining program, electrode hole finishing bosses of two first rows of electrode holes 301 in the area of a third plurality of rows of electrode holes 304 are used for electric machining to Ra0.4um, the allowance is 0.01mm, after the second section of electric machining program is finished, the first formed part 3 on the magnetic table plane 33 is taken down for boss size measurement and surface roughness measurement, electric machining parameter optimization adjustment is carried out according to the actually measured allowance and roughness, and finally, the boss sizes of the electrodes Kong Jingxiu of the two first rows of electrode holes 301 in the area of the third section of electric machining program and the fourth plurality of rows of electrode holes 305 are used for optimizing adjustment to reach 0.000-0.003 mm, the surface roughness is reached to Ra0.2um and the boss root sharp angle is reached to R0.03max; taking down the first formed part 3 again to detect whether the formed part is qualified or not, if the formed part is unqualified, continuously optimizing and adjusting the electric machining parameters, and continuously finishing until the formed part is qualified; after the electric spark preprocessing is finished, in the process of performing formal electric machining, the three-section electric machining program can be executed at one time, the formed part is not required to be taken down for inspection in the second section program, the formed part is not required to be taken down for inspection until the three-section electric machining program is executed, no problem exists under normal conditions, and if the formed part is unqualified, the formed part is required to be trimmed again; every time a new machined part is started, a new electrode Kong Lieshu corresponding to 1 area needs to be added, each formed part needs to ensure electrode holes with 4 areas, and the third procedure needs to use the new electrode holes after the addition.

Regarding the lowering surface of the tool electrode, as shown in fig. 24, after the electrode hole on the tool electrode 17 is used, the special fixture 30 with the tool electrode 17 connected with the head 500 of the forming electric spark machine is taken down, the tool electrode 17 is subjected to first lowering surface processing according to the height of the boss on the forming part by wire cutting (slow wire feeding), the position 37 of the first lowering surface tool electrode is a first lowering surface termination line, h1 is the first lowering surface height, a galvanized wire of ⌀ 0.1.1 mm is selected, the processing technology of rough cutting once and finishing four times is adopted, the first rough cutting leaves a margin of 0.04mm, the second fine cutting leaves a margin of 0.01mm, the third fine finishing leaves a margin of 0.003mm, the fourth finishing is performed, and the surface is controlled within Ra0.25um; after the surface is lowered, the special fixture 30 with the tool electrode 17 is connected with the machine tool head 500 again, the electric discharge machining can be directly performed on the boss on the formed part, after the electrode hole is used, the second surface lowering machining is performed by the same method, the position 38 of the second surface lowering tool electrode is the second surface lowering termination line, h2 is the second surface lowering height, and h3 needs to be ensured to be more than or equal to 2mm.

The electric machining method of the boss on the molded part in the upper die and the lower die is the same in the whole electric spark machining process, and only electric machining is finished on two different electric spark machines respectively.

Finally, it should be noted that: the foregoing description is only of the preferred embodiments of the invention and is not intended to limit the scope of the invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A processing method for machining precision small boss molded parts by electric spark is characterized by comprising the following steps of: the method comprises the following steps:

carrying out electric machining on a boss on the molded part;

the boss distribution mode of each molded part of the molded part is in column distribution, each molded part is provided with at least one column of bosses, the shape of each boss is consistent, and the distance between two adjacent bosses in each column is equal; the unit of the electric spark machining quantity is a column;

Determining the number of electric spark machining, wherein the sum of the number of boss rows on each row of molded parts of the same molded part is taken as the number of electric spark machining;

the electrode three-dimensional model is also provided with a square reference outer frame positioned at the periphery of the electrode hole area and at least one locking threaded through hole arranged on the clamping part;

respectively thickening the other sides except one side of the clamping part in the circumferential direction of the square reference outer frame of the electrode three-dimensional model, and respectively creating at least one connecting threaded through hole and at least one positioning connecting hole on the thickened physical characteristics to form a tool electrode auxiliary model comprising the electrode three-dimensional model;

an electrode tool corresponding to the electrode three-dimensional model is processed, comprising the following steps:

2. The method for machining the precision fine boss-like molded parts by electric spark machining according to claim 1, wherein the method comprises the steps of: determining an electrical machining gap, a height and an electrode hole number of a tool electrode for electrical discharge machining, comprising the steps of:

determining an electric machining gap of the tool electrode, and obtaining the electric machining gap through a formula S (F-0.09)/2, wherein S is the electric machining gap and the selection range is 0.03 mm-0.10 mm, F is the minimum distance between bosses on the formed part, and 0.09mm is the minimum thickness between electrode holes on the tool electrode;

3. The method for machining the precision fine boss-like molded parts by electric spark machining according to claim 1, wherein the method comprises the steps of: in determining the tool electrode upper electrode Kong Lieshu, the tool electrode has a number of times of use of the degradable surface, which can be found by the calculation formula g= (H-2)/H, where G is the number of times of use of the degradable surface, H is the height of the tool electrode, and H is the height of the boss on the molded part.

4. The method for machining the precision fine boss-like molded parts by electric spark machining according to claim 1, wherein the method comprises the steps of: the die is provided with two forming parts and is divided into an upper die and a lower die, the upper die and the lower die are composed of a plurality of forming parts with a plurality of bosses, the distance between the bosses on the upper die and the lower die is smaller than 0.4mm, and the maximum cross section size of the bosses on the forming parts is smaller than or equal to 0.35mm;

5. The method for machining the precision fine boss like molded parts by electric spark machining according to claim 4, wherein the method comprises the steps of: after modeling the electrode three-dimensional model, the method further comprises the steps of assembling all the molded parts with the tool electrode, wherein the assembling method comprises the following steps:

6. The method for machining the precision fine boss-like molded parts by electric spark machining according to any one of claims 1 to 5, characterized in that: and (3) carrying out electric machining of the boss on the molded part, comprising the following steps of:

7. The method for machining the precision fine boss like molded part by electric spark machining according to claim 6, wherein the method comprises the steps of: in the electro-machining process of the boss on the formed part, the method also comprises a tool electrode using method, and the using method comprises the following steps: