CN111546463A - Machining method and machining tool for ultra-large lead multi-start ceramic threads - Google Patents
Machining method and machining tool for ultra-large lead multi-start ceramic threads Download PDFInfo
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- CN111546463A CN111546463A CN202010406733.0A CN202010406733A CN111546463A CN 111546463 A CN111546463 A CN 111546463A CN 202010406733 A CN202010406733 A CN 202010406733A CN 111546463 A CN111546463 A CN 111546463A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
- B28B3/003—Pressing by means acting upon the material via flexible mould wall parts, e.g. by means of inflatable cores, isostatic presses
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/08—Apparatus or processes for treating or working the shaped or preshaped articles for reshaping the surface, e.g. smoothing, roughening, corrugating, making screw-threads
- B28B11/0854—Apparatus or processes for treating or working the shaped or preshaped articles for reshaping the surface, e.g. smoothing, roughening, corrugating, making screw-threads for making screw-threads or the like in the surface of the shaped article
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/12—Apparatus or processes for treating or working the shaped or preshaped articles for removing parts of the articles by cutting
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Abstract
The invention provides a method for machining a super-large lead multi-start ceramic thread, which comprises the following steps: step S1 of configuring multiple groups of sample powder to obtain average green compact compression ratio data and average sintering shrinkage; step S2, preparing granulated powder, and pressing the granulated powder by adopting isostatic cool pressing to form a blank with uniform density; step S3, preparing a specific thread cutter according to a preset helix angle and left and right back angles, configuring the thread cutter with a numerical control lathe, and turning the green body according to the average green body compression ratio data and the average sintering shrinkage ratio data; and step S4, in which the green body is configured and calcined to form a primary sintered product, replaces the problem that the multi-start ceramic thread is easy to crack due to the surface contact grinding mode between the threaded cutter and the thread groove of the large-lead multi-start ceramic thread in the prior art, and adopts the line contact grinding mode between the cutter and the groove wall of the thread groove before sintering to reduce the abrasion of the thread groove in the grinding process.
Description
Technical Field
The invention belongs to the technical field of ceramic product processing and forming, and particularly relates to a method and a tool for processing an ultra-large lead multi-start ceramic thread.
Background
Ceramic is a common material, and is known as an engineering material which has the advantages of strong rigidity, high hardness and high compression resistance, has excellent chemical stability at high temperature, and has the characteristics of low tensile strength, poor plasticity and poor toughness. Because of the characteristics of the ceramic material, the ceramic product has poor reworking performance and high processing difficulty.
The process of the prior ceramic product can be roughly divided into three steps of cold equal pressing, sintering and final grinding. Specifically, the granulated powder is pressed into a blank by cold isostatic pressing, the blank is turned before sintering according to the processing specification and size before sintering, then the turned finished blank is sintered at high temperature, and ceramic grinding is carried out after sintering to obtain the final formed finished product.
For example, in the process of processing a ceramic product with multiple threads, because the ceramic product has 15% -20% sintering shrinkage and 0.5% -1% sintering deformation during the sintering process, the finished product of the ceramic product with multiple threads after initial firing often does not meet the corresponding precision requirement.
One conceivable solution is to perform grinding (turning, milling, drilling) on a multi-start threaded portion of a preliminarily fired product after the preliminary firing of a ceramic product having a multi-start thread is completed so as to satisfy the dimensional and specification requirements, and finally perform precision grinding on portions other than the multi-start thread so as to process the product characteristics thereof. However, this method is only suitable for small pitch threads within 20 mm. The reason for this is that, when the method is used for processing a ceramic product having a large-pitch thread, the sintering shrinkage and deformation amount of the ceramic product of the large-pitch thread are larger according to the same sintering shrinkage and sintering deformation rate, and thus, the thread part thereof is highly likely to be cracked during sintering.
Another conceivable solution is to apply a precision grinding process to the multi-start threaded portion, that is, to precision grind the primary sintered product as a whole. Fig. 1 is a state diagram showing a state in which a threaded portion of a primary sintered product is subjected to precision grinding in the prior art. In the precision grinding process, a rotating grinding wheel 10 is adopted to grind the surface of an object so as to enable the surface of the object to meet the specification, size and the like of the design requirement, referring to fig. 1, in the process, because a primary sintered product 20 and the grinding wheel 10 are in a rotating state, when a thread groove is ground, two sides of the grinding wheel 10 are inevitably in surface contact with two side surfaces of the thread groove 21 after the grinding wheel 10 rotates, particularly, when a large-lead or even ultra-large-lead multi-thread is machined, the grinding wheel 10 can form interference over-cutting on the two side surfaces of the thread groove 21, namely, in the grinding process, the grinding wheel 10 can not avoid grinding with the thread groove wall 22 except for grinding the thread groove 21, when the lead of the ceramic large-lead thread is increased and the depth is further deepened, the phenomenon that the thread is cracked and cracked in the precision grinding process can be further caused by the surface contact between the grinding wheel 10 and the, directly causing the product to be scrapped. Therefore, ceramic products with large leads, especially with very large leads and deep threads, cannot be machined by applying a precision grinding process.
In view of the above, the prior art should be improved to solve the technical problems of high processing difficulty, long processing time and high rejection rate in the processing process of the large-pitch thread multi-start ceramic.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a machining method and a machining tool for the large-lead multi-start ceramic threads, which can solve the technical problems that the machining difficulty of the large-lead and large-lead multi-start ceramic threads is high, the machining time is long, and the rejection rate is high due to the fact that the large-lead multi-start ceramic threads are easy to crack in the sintering process in the prior art.
In order to solve the technical problems, the invention adopts a technical scheme that: the method for machining the ultra-large lead multi-start ceramic thread comprises the following steps: step S1 of configuring multiple groups of sample powder to obtain average green compact compression ratio data and average sintering shrinkage; step S2, preparing granulated powder, and pressing the granulated powder by adopting isostatic cool pressing to form a blank with uniform density; step S3, preparing a specific thread cutter according to a preset helix angle and left and right back angles, configuring the thread cutter with a numerical control lathe, and turning the green body according to the average green body compression ratio data and the average sintering shrinkage ratio data; and S4, calcining the green body to sinter the green body to form a primary sintered product.
Preferably, in the step S1, the step of obtaining the average green compact compression ratio and average sintering shrinkage data includes a step S11 of cold isostatic pressing the plurality of sets of powder materials under the same conditions to obtain a plurality of formed green compacts, and obtaining green shrinkage ratio data of the plurality of sets of formed green compacts; a step S12 of sintering the plurality of green compacts under the same conditions to obtain sintering shrinkage data of the plurality of sets of molded green compacts; and S13, obtaining average green compression ratio data and average sintering shrinkage ratio data according to the multiple groups of green shrinkage ratio data and sintering shrinkage ratio data in a weighting mode.
Further preferably, in the step S3, the method further includes a step S31 of calculating the size of the green body before sintering according to the average green compression ratio data and the average sintering shrinkage ratio data.
Still more preferably, in step S3, the cutting blade angle is set to 6 degrees, the thread demand angle is set to 30 degrees, and the angles of the two side edges are set to be in the range of 3 degrees to 5 degrees.
Still further preferably, in step S3, during the turning process, the threading tool is fixed, and as the multi-start thread rotates, both side edges of the threading tool successively come into linear contact with both side groove surfaces of the thread groove of the multi-start thread.
Still further preferably, in step S3, the numerical control lathe is configured with parameters according to a preset major diameter and minor diameter of the thread, and a width, a lead, and the number of thread starts of the threading tool.
Preferably, in the step S4, the calcining process further includes: center circumference equidistant ground sets up and sets up a plurality of logical grooves on the smelting tool square plate, lead to the groove edge the square plate thickness direction runs through, and makes two arbitrary logical grooves in a plurality of logical grooves all form the symmetry with the square plate center.
Correspondingly, the invention also provides an ultra-large lead multi-head ceramic thread machining tool applied to the ultra-large lead multi-head ceramic thread machining method, the tool comprises a tool handle and a tool bit formed at the end part of the tool handle, the tool bit comprises a first tool face and a second tool face, the planes of the first tool face and the second tool face are respectively vertical to the vertical plane and extend along the direction from the tool handle to the tool bit, the included angle between the plane of the first tool face and the plane of the second tool face is in the range of 20-40 degrees, the tail ends of the first tool face and the second tool face are intersected to form a cutting edge, and the notch of the cutting edge is in a ladder shape.
Preferably, the cutter left and right relief angles are in the range of 3 to 5 degrees.
Further preferably, when the tool is used for machining a multi-start ceramic thread, the thread tool is fixed, and along with the rotation of the multi-start thread, the first tool face and the second tool face of the thread tool are in linear contact with the groove faces on the two sides of the thread groove of the multi-start thread in sequence, and the groove faces on the two sides of the thread groove are cut.
Compared with the prior art, the invention has the following beneficial technical effects due to the adoption of the technical scheme:
1. the method comprises the steps of (1) performing compression sintering on multiple groups of samples in advance because the granulated powder is compressed into a green body and also has green body shrinkage in the sintering process, and calculating compression ratio data of multiple groups of green bodies and the sintering shrinkage ratio of a primary sintered product sintered under the same condition after cold isostatic pressing under the same condition to obtain average compression ratio data and average sintering shrinkage ratio data of the green bodies, so that a grinding process performed after sintering in the prior art is arranged in front of a sintering process, and the large-lead multi-start ceramic threads and the extra-large-lead multi-start ceramic threads on the primary sintered product formed after sintering are directly designed in a composite mode to meet the rated specification and size requirements;
2. in order to achieve the technical effects, a special thread cutter needs to be designed according to the size of a green body, the problem that the multi-start ceramic thread is easy to crack due to a grinding mode of surface contact between the thread cutter and a thread groove of the large-lead multi-start ceramic thread in the prior art is solved, a grinding mode of line contact between the cutter and the wall of the thread groove is adopted before sintering, and the specific cutter is configured with a cutting edge angle, so that the interference between a cutting edge and the thread groove can be avoided, and the abrasion of the thread groove in the grinding process is reduced;
3. according to the average green body compression ratio data and the average sintering shrinkage ratio data, the accurate size of the green body before sintering can be calculated according to the size of the finished product after sintering, and therefore turning before sintering is carried out on the green body before sintering according to the calculated accurate size of the green body before sintering;
4. and according to the calculated accurate size of the green body before sintering, configuring the cutting-in cutter angle and the left and right back angle angles of the side edge of the special cutter. The plane of the first knife face and the plane of the second knife face of the tool bit are perpendicular to the vertical plane and extend from the tool shank to the tool bit direction, the included angle between the planes of the two knife faces is in the range of 20-40 degrees, and a trapezoidal cutting edge is formed at the intersection, so that during practical processing, the cutting edge is arranged in a thread groove of a multi-start ceramic thread, the position of the tool is kept fixed, a green body is rotated, the side wall of the thread groove of the ceramic thread is sequentially in linear contact with the first knife face and the second knife face to complete turning, and thread cracking caused by the contact turning of the knife faces and the thread groove face is avoided, so that the number of knives required under the same drop of a blank is obviously reduced, the tool moving speed is improved, and the processing efficiency is also improved;
5. for reducing the thermal tension of smelting tool among the high temperature sintering process, make the finished product size that the product leads to because of shrinkage deformation uncontrollable, before the sintering, set up a plurality of logical grooves around square plate center circumference equidistant on the smelting tool square plate, and make two arbitrary logical grooves in a plurality of logical grooves all form the symmetry with the square plate center, thereby in the high temperature calcination in-process, because the existence in logical groove has reduced the deformation that the smelting tool produced because of thermal tension, thereby finished product size accuracy has been guaranteed, then make the sintering accomplish the back finished product need not to pass through the specification and the size that the grinding can satisfy the demand again, also namely, after the sintering is accomplished, big helical pitch bull ceramic thread part direct forming.
Drawings
FIG. 1 is a state diagram showing a state in which a threaded portion of a primary sintered product is subjected to precision grinding in the prior art;
FIG. 2 is a flow chart showing a flow of a method of making a super-lead multi-start ceramic thread in accordance with a preferred embodiment of the present invention;
FIG. 3 is a flow chart illustrating a flow of obtaining average green compression ratio and average sintering shrinkage data for the preferred embodiment shown in FIG. 2;
FIG. 4 is a side view showing the configuration of the side of a particular thread cutter in the preferred embodiment of the invention;
FIG. 5 is a top view showing the top view configuration of the particular thread cutting tool shown in FIG. 4;
FIG. 6 is a state diagram showing the specific thread cutting tool shown in FIG. 4 positioned in the thread groove of a multi-start ceramic thread and in linear contact with the groove wall during actual machining;
fig. 7 is a top view showing a top view of the jig square plate with through slots in the preferred embodiment shown in fig. 2.
Detailed Description
An embodiment of a method and a tool for machining a ceramic thread with a large lead and a large number of threads according to the present invention will be described with reference to the accompanying drawings. Those of ordinary skill in the art will recognize that the described embodiments can be modified in various different ways, without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims. Furthermore, in the present description, the drawings are not to scale and like reference numerals refer to like parts.
It should be noted that, in the embodiments of the present invention, the expressions "first" and "second" are used to distinguish two entities with the same name but different names or different parameters, and it is understood that "first" and "second" are merely for convenience of description and should not be construed as limitations of the embodiments of the present invention, and the descriptions thereof in the following embodiments are omitted.
Fig. 2 is a flow chart showing a flow of a method for machining a super-lead multi-start ceramic thread according to a preferred embodiment of the present invention. Referring to fig. 2, the method of machining a super-lead multi-start ceramic thread in the preferred embodiment of the present invention includes the steps of: step S1 of configuring multiple groups of sample powder to obtain average green compact compression ratio data and average sintering shrinkage; step S2, preparing granulated powder, and pressing the granulated powder by adopting isostatic cool pressing to form a blank with uniform density; step S3, preparing a specific thread cutter according to a preset helix angle and left and right back angles, configuring the thread cutter with a numerical control lathe, and turning the green body according to the average green body compression ratio data and the average sintering shrinkage ratio data; and S4, calcining the green body to sinter the green body to form a primary sintered product.
Specifically, in step S1, considering that the green body will shrink during the cold isostatic pressing process and the sintering process, 10 groups of powders are selected to be sampled, the size of the pressed money of each group of powders is recorded, the cold isostatic pressing process is performed according to the same process and pressure environment, the sizes of multiple groups of pressed green bodies are recorded, the high-temperature calcination is performed according to the same temperature, and the size data of the primary sintered product formed by sintering is recorded. For example, in the preferred embodiment, the size of the green body before sintering is 12.55, the size of the green body after sintering is 10, the sintering shrinkage is 1.255, and the average sintering shrinkage data is obtained by sampling the sintering shrinkage for each of the plurality of sets of powders and weighting and averaging the samples. Therefore, the size of the blank before sintering can be calculated according to the actual specification of finished product processing and the average sintering shrinkage rate, so that the primary sintered product formed after sintering meets the thread parameters of the design requirements, such as the major diameter, the minor diameter, the lead, the number of thread heads and the like. Accordingly, in other embodiments of the present invention, the amount of powder may also be determined at the cold isostatic pressing cost based on the average green compression ratio obtained from multiple sets of samples, and embodiments of the present invention are not limited thereto. FIG. 3 is a flow chart showing the process of obtaining the average green compression ratio and average sintering shrinkage data in the preferred embodiment shown in FIG. 2. the process of determining the average green compression ratio and average sintering shrinkage by multiple sets of samples as described above is shown in FIG. 3.
After the size of the blank before sintering is determined, a special thread cutter can be configured according to the size of the blank before sintering. In order to solve the problem of thread cracking in the sintering process and the grinding process of a primary sintered product after sintering in the prior art, a linear contact cutter is adopted to cut a blank before sintering instead of a mode of adopting a grinding wheel to carry out surface contact grinding after sintering in the prior art, so that the problem is solved. Specifically, FIG. 4 is a side view showing the configuration of the side of the particular thread cutting tool in the preferred embodiment of the present invention. Fig. 5 is a top view showing the top view configuration of the particular thread cutting tool shown in fig. 4. Referring to fig. 4 and 5, in the preferred embodiment of the present invention, the cutting angle, the thread forming demand angle, and the left and right relief angles of the tool are configured according to the estimated size of the pre-sintered blank. In the embodiment, the cutting-in cutter angle is 6 degrees, 10 degrees are used for discharging cutting powder, 30 degrees are used for designing the required angle of the super-lead multi-start ceramic thread forming in the embodiment, and the left and right back angles of the two side edges are in the range of 3 degrees to 5 degrees so as to ensure symmetrical cutting in the forward and reverse cutting process.
After the cutter configuration is completed, configuring the cutter and the numerical control machine tool, configuring numerical control parameters including thread large diameter, small diameter, thread cutter width, thread lead, thread head number, thread length, radial cutting amount, axial cutting amount, thread groove width and the like, then configuring and calling the parameters, calculating a substitute value for the variables, sending an instruction, carrying out radial groove expansion on a blank by equipment, then correspondingly recalculating the substitute value and sending the instruction, carrying out axial groove expansion on the blank by the equipment, forming the large-lead multi-head ceramic thread which meets the design requirement, and exiting after processing to obtain the blank before sintering.
Fig. 6 is a state diagram showing a state in which the specific thread cutting tool shown in fig. 4 is disposed in the thread groove of the multi-start ceramic thread and is in linear contact with the groove wall during actual machining. Referring to fig. 6, in the turning process of the preferred embodiment of the present invention, unlike the process of synchronously rotating the grinding wheel and the blank in the prior art, the specific threaded tool 30 is kept fixed, and the blank 20 is rotated, so that the two side edges of the threaded tool 30 are in linear contact with the two side groove surfaces 22 of the thread groove 21 of the multi-start thread of the blank 20 in sequence, that is, at any time of machining, because the specific tool is configured with the cutting edge angle, the interference between the cutting edge and the thread groove can be avoided, and one side tool surface of the tool bit is in linear contact with the groove wall of the thread groove.
The sintering process is to place the blank on a sintering jig for calcination, raise the temperature from room temperature to 1530 ℃, and continuously calcine for 120 hours to 130 hours, thereby obtaining a sintered primary sintering finished product. In this in-process, for reducing the thermal tension of smelting tool among the high temperature sintering process, make the finished product size that the product warp to lead to because of the shrink uncontrollable, before the sintering, set up a plurality of logical grooves around square plate center circumference equidistant on the smelting tool square plate, and make two arbitrary logical grooves in a plurality of logical grooves all form the symmetry with the square plate center, thereby in the high temperature calcination in-process, because the existence in logical groove has reduced the smelting tool because of the deformation that thermal tension produced, thereby finished product size accuracy has been guaranteed, then make the sintering accomplish the back finished product need not to pass through the specification and the size that the grinding can satisfy the demand again, also, that is, after the sintering is accomplished, big helical pitch bull ceramic thread part direct forming. Fig. 7 is a top view showing a top view of the jig square plate with through slots in the preferred embodiment shown in fig. 2. Referring to fig. 7, in the preferred embodiment of the present invention, the size of the square plate 50 of the tool is 550 mm × 550 mm square plate, four through grooves 51 penetrating the surface of the square plate in the thickness direction of the square plate are formed on the square plate 50 of the tool, the diameter of each through groove 51 is 2 mm, the distance between the notch and the end points of the edge where the notch is located is 198 mm and 350 mm, respectively, and the four through grooves 51 are distributed clockwise at equal intervals according to a fixed deflection angle, and the four through grooves 51 satisfy that any two through grooves are symmetrical with respect to the center of the square plate 50 of the tool, or the connecting line between the notch of each through groove 51 and the center of the square plate 50 of the tool is inclined clockwise at a fixed inclination angle with respect to the horizontal or vertical direction.
Referring back to fig. 4 and 5, the method for machining a ceramic thread with a large lead and multiple threads is implemented based on a specific thread tool, and accordingly, the invention also provides a tool for machining a ceramic thread with a large lead and multiple threads. As shown in the drawing, the threading tool 40 includes a shank 41 and a cutting head 42 formed at an end of the shank 41, and the cutting head 42 includes a first cutting surface 421 and a second cutting surface 422, and a vertical plane is taken as a reference plane, so that the planes of the first cutting surface 421 and the second cutting surface 422 are intersecting planes, and both extend perpendicularly to the vertical plane in a direction from the shank 41 to the cutting head 42. In the preferred embodiment, the included angle between the plane of the first cutting surface 421 and the plane of the second cutting surface 422 is 30 degrees when they intersect, in other embodiments of the present invention, the included angle between the planes of the first cutting surface 421 and the second cutting surface 422 can be adjusted to be in the range of 20 degrees to 40 degrees according to specific machining specifications. In addition, the ends of the first blade surface 421 and the second blade surface 422 meet to form a blade 423, the cut of the blade 423 is trapezoidal, and the left and right clearance angle of the blade is 4 degrees and can be adjusted within a range of 3 degrees to 5 degrees. Referring back to fig. 6, in actual machining, the threaded tool 40 is kept fixed, the multi-thread portion rotates along with the rotation of the blank 20, and then the first tool surface 421 and the second tool surface 422 of the threaded tool 40 sequentially and linearly contact and cut with the groove surfaces 22 on the two sides of the thread groove 21 of the multi-thread, so as to replace the surface cutting mode between the grinding wheel and the thread groove when the grinding wheel and the blank synchronously rotate as shown in fig. 1 in the prior art.
Compared with the prior art, the invention has the following beneficial technical effects due to the adoption of the technical scheme:
1. the method comprises the steps of (1) performing compression sintering on multiple groups of samples in advance because the granulated powder is compressed into a green body and also has green body shrinkage in the sintering process, and calculating compression ratio data of multiple groups of green bodies and the sintering shrinkage ratio of a primary sintered product sintered under the same condition after cold isostatic pressing under the same condition to obtain average compression ratio data and average sintering shrinkage ratio data of the green bodies, so that a grinding process performed after sintering in the prior art is arranged in front of a sintering process, and the large-lead multi-start ceramic threads and the extra-large-lead multi-start ceramic threads on the primary sintered product formed after sintering are directly designed in a composite mode to meet the rated specification and size requirements;
2. in order to achieve the technical effects, a special thread cutter needs to be designed according to the size of a green body, the problem that the multi-start ceramic thread is easy to crack due to a grinding mode of surface contact between the thread cutter and a thread groove of the large-lead multi-start ceramic thread in the prior art is solved, a grinding mode of line contact between the cutter and the wall of the thread groove is adopted before sintering, and the specific cutter is configured with a cutting edge angle, so that the interference between a cutting edge and the thread groove can be avoided, and the abrasion of the thread groove in the grinding process is reduced;
3. according to the average green body compression ratio data and the average sintering shrinkage ratio data, the accurate size of the green body before sintering can be calculated according to the size of the finished product after sintering, and therefore turning before sintering is carried out on the green body before sintering according to the calculated accurate size of the green body before sintering;
4. and according to the calculated accurate size of the green body before sintering, configuring the cutting-in cutter angle and the left and right back angle angles of the side edge of the special cutter. The plane of the first knife face and the plane of the second knife face of the tool bit are perpendicular to the vertical plane and extend from the tool shank to the tool bit direction, the included angle between the planes of the two knife faces is in the range of 20-40 degrees, and a trapezoidal cutting edge is formed at the intersection, so that during practical processing, the cutting edge is arranged in a thread groove of a multi-start ceramic thread, the position of the tool is kept fixed, a green body is rotated, the side wall of the thread groove of the ceramic thread is sequentially in linear contact with the first knife face and the second knife face to complete turning, and thread cracking caused by the contact turning of the knife faces and the thread groove face is avoided, so that the number of knives required under the same drop of a blank is obviously reduced, the tool moving speed is improved, and the processing efficiency is also improved;
5. for reducing the thermal tension of smelting tool among the high temperature sintering process, make the finished product size that the product leads to because of shrinkage deformation uncontrollable, before the sintering, set up a plurality of logical grooves around square plate center circumference equidistant on the smelting tool square plate, and make two arbitrary logical grooves in a plurality of logical grooves all form the symmetry with the square plate center, thereby in the high temperature calcination in-process, because the existence in logical groove has reduced the deformation that the smelting tool produced because of thermal tension, thereby finished product size accuracy has been guaranteed, then make the sintering accomplish the back finished product need not to pass through the specification and the size that the grinding can satisfy the demand again, also namely, after the sintering is accomplished, big helical pitch bull ceramic thread part direct forming.
The present invention has been described in detail, and the embodiments are only used for understanding the method and the core idea of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and to implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (10)
1. A method for machining an ultra-large lead multi-start ceramic thread is characterized by comprising the following steps:
step S1 of configuring multiple groups of sample powder to obtain average green compact compression ratio data and average sintering shrinkage;
step S2, preparing granulated powder, and pressing the granulated powder by adopting isostatic cool pressing to form a blank with uniform density;
step S3, preparing a specific thread cutter according to a preset helix angle and left and right back angles, configuring the thread cutter with a numerical control lathe, and turning the green body according to the average green body compression ratio data and the average sintering shrinkage ratio data;
and S4, calcining the green body to sinter the green body to form a primary sintered product.
2. The method of machining a super-lead multi-start ceramic thread of claim 1 wherein in step S1, the step of obtaining the average green compression ratio and average sintering shrinkage data includes
A step S11 of performing cold isostatic pressing on the multiple groups of powder under the same condition to obtain multiple formed green bodies and acquiring green body shrinkage ratio data of the multiple groups of formed green bodies;
a step S12 of sintering the plurality of green compacts under the same conditions to obtain sintering shrinkage data of the plurality of sets of molded green compacts;
and S13, obtaining average green compression ratio data and average sintering shrinkage ratio data according to the multiple groups of green shrinkage ratio data and sintering shrinkage ratio data in a weighting mode.
3. The method of machining a super-lead multi-start ceramic thread according to claim 2, further comprising a step S31 of calculating the size of the green body before sintering from the average green compression ratio data and the average sintering shrinkage ratio data in the step S3.
4. The method of claim 3, wherein in the step S3, the cutting blade angle is set to 6 degrees, the thread demand angle is set to 30 degrees, and the angles of the two side edges are set to 3 to 5 degrees.
5. The method of machining an ultra-large lead multi-start ceramic thread according to claim 4, wherein in the step S3, during turning, the threading tool is fixed, and as the multi-start thread rotates, two side edges of the threading tool successively make linear contact cutting with two side groove surfaces of a thread groove of the multi-start thread.
6. The method of machining a ceramic thread with ultra-large lead and multiple threads according to claim 4, wherein in step S3, the numerical control lathe is configured according to the preset major diameter and minor diameter of the thread, and the width, lead and number of thread starts of the threading tool.
7. The method of machining a super-lead multi-start ceramic thread according to claim 1, wherein in the step S4, the calcining process further comprises:
center circumference equidistant ground sets up and sets up a plurality of logical grooves on the smelting tool square plate, lead to the groove edge the square plate thickness direction runs through, and makes two arbitrary logical grooves in a plurality of logical grooves all form the symmetry with the square plate center.
8. An ultra-large lead multi-start ceramic thread machining tool according to claims 1 to 7, wherein the tool comprises a shank and a tool bit formed at an end of the shank, the tool bit comprises a first tool face and a second tool face, the planes of the first tool face and the second tool face are perpendicular to a vertical plane respectively and extend in a direction from the shank to the tool bit, wherein,
the included angle between the plane of the first knife face and the plane of the second knife face is in the range of 20 degrees to 40 degrees, the tail ends of the first knife face and the second knife face are intersected to form a knife edge, and the cut of the knife edge is in a ladder shape.
9. The ultra-lead multi-start ceramic threading tool of claim 8 wherein said tool left and right relief angle is in the range of 3 degrees to 5 degrees.
10. The ultra-large lead multi-start ceramic thread machining tool according to claim 8 or 9, wherein the tool is used for machining a multi-start ceramic thread, the thread tool is fixed, and the first tool face and the second tool face of the thread tool are in linear contact with the groove faces on both sides of the thread groove of the multi-start thread in sequence along with the rotation of the multi-start thread, and cut the groove faces on both sides of the thread groove.
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