RU2147496C1 - Sectional worm milling cutter - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: worm milling cutter has body and rotary nonreground cutting plates positioned along profiling lines directed according to normal to side cutting edges of teeth through profiling pole lying at cross-point of initial straight line with interaxial perpendicular of milling cutter and article. To avoid drawbacks associated with complexity of manufacture, especially for average and small modules, milling cutter is provided with racks where rotary nonreground cutting plates are alternately mounted. Modified sections of profile adequate to profile of given part of rack tooth are made on these plates. The plates are positioned in plane of rack tooth profile, in sections limited by projections of profiling lines on middle and extreme rack teeth adjacent to it. EFFECT: higher efficiency. 17 cl, 6 dwg

Description

 The invention relates to the field of engineering, in particular to worm tools for processing gear products.

 Worm mills are known in which the cutting edges on the right and left sides of the tooth are equipped with prismatic inserts (see German Patent N 2753286, M. CL B 23 F 21/16 Mehrteiliger Abwalzfa-ser.Anmeldetag 30.11.77, Anmelder Sack GmbH, Dusseldorf). The use of replaceable inserts of a different shape for such mills is not provided.

 Also known are prefabricated worm mills for machining gear products, equipped with replaceable non-rotatable cutting inserts mounted on the side of the teeth along the line of machine engagement (see ed. St. USSR N 629023, Prefabricated worm mill, MKI B 23 F 21/16, application N 2484590 / 25-08 from 12.05.77, author Sidorenko A.K., BI N 39 from 10.25.78). The disadvantage of this cutter is the complexity of execution, especially for medium and small modules.

 In the present invention, these disadvantages are eliminated by alternately equipping the teeth of the worm tools with replaceable non-rotatable cutting inserts having modified sections of the profile on the sides to align them with the profile of the cutter tooth, which are installed in the plane of its profile on the top, in the middle part and on the leg in the profiling lines, as well as new options for installing and fixing plates and rails.

 Descriptions of the proposed cutters are illustrated in the drawings.

In FIG. 1 shows a worm milling cutter having rails 1, in which the middle teeth 2 are aligned with the center axis of the milling cutter and the product, the intersection point of which with the dividing line (dp) is the profile pole P _о , and the outer teeth 3 and 4 are connected with the profile lines A _l C _l P _o B _p and A _p C _p P _o B _l , which are the normals drawn through the profiling pole P _o to the left and right side cutting edges of the rack teeth with profile angles α _o equal to the angle of machine engagement c _o . The teeth 2 located along the milling cutter turn in their extreme positions 5 and 6 coincide with the extreme positions of the teeth 3 and 4, which limits their profiling sections with points C _l D _l and C _p D _p respectively on the left and right sides of the teeth and eliminates the need for placement of cutting inserts outside of these areas. Therefore, on the turn of the middle teeth 2, the cutting inserts 7 are installed only in their middle part, with overlapping projections of the points C _l D _l C _p D _p on the cutting edges of the tooth, for example, by a value of (0.01 ... 0.3) m, where m is the tooth modulus. On the turns of the extreme teeth 3, 4, the cutting inserts 8 are installed only at the vertices, with overlapping projections of points A _l C _l A _p C _p , and the inserts 9 are only at the legs, with overlapping projections of points D _l B _l D _p B _p . The profile of the cutter tooth having a height h _o , head height h _a leg height h _f , width S _o and profile angle α _o on the dividing line (dp), as well as points A _l A _p C _l C _p P _o D _l D _p B _l B _p profiling lines uniquely determine the parameters and installation height for the plates of the selected shape, which can be various shapes, for finishing mills - hexahedrons 7, 8, 9 (Fig. 1, a), for semi-finished - hexagons 9, 10, 11 (Fig. 1, b), and for rough - hexagons 12, 13, 14 (Fig. 1, c) with combined straight-arc protrusions to form undercut pripu ka for final processing or manufacturing hexahedrons teeth 15, 16, 17 (FIG. 1 g) with a projecting head arc.

 The proposed milling cutters for finishing provide adequate conditions for the formation of the teeth of the product, adequate to the basic milling cutters, by reducing the number of profiling plates by 4/9, eliminating the need to install the plates in the overlay, which allows 1/3 to increase the number of rails, thereby increasing the resistance or productivity of the milling cutters. At the same time, the design of cutters and the manufacturability of their manufacture and maintenance are simplified, but their installation requires accurate orientation relative to the center axis.

 Non-profiling sections of semi-finished and rough mills remain cutting, therefore, on the middle and extreme teeth, the plates can alternate in the reverse order through one rail or can be installed in the overlay, which eliminates the need for precise axial installation of mills (this option is also possible for finishing mills).

In FIG. 2 shows new versions of milling cutters having adequate rails 1 with middle 2 and extreme 3, 4 teeth with profile h _o , h _a , h _f , s _o , α _o and profiling lines A _l C _l P _o D _l B _l and A _p C _p P _o D _p B _p , which differ from previous finishing mills in that between the plates 5 and 6 (Fig. 2, a) mounted on the head and tooth leg, a compensator 7 is placed, which reduces the size of the plates and reduces the consumption of tool materials. For semi-finished and rough cutters, compensators 10 between plates 8 and 9 (Fig. 2, b), compensators 13 between plates 11 and 12 (Fig. 2, c) compensators 16 between plates 14 and 15 (Fig. 2, d) can be cutting, while their profile repeats the profile of a given section of the cutter tooth, but with less accuracy.

 In FIG. 3 shows the main types of plates for equipping the teeth of the cutters. On the leg, in addition to the 6-faced finishing (Fig. 3, a) and semi-finished (Fig. 3, b), 10-faced rough with straight flanking areas (Fig. 3, c) and depressions (Fig. 3, d), 9-sided finishing and semi-finishing (Fig. 3, e, f), 9-faceted rough with straight (Fig. 3, g) and arc (Fig. 3, h) flanking sections, 8-sided finishing and semi-finishing can be installed (Fig. 3, and), 8-sided with flats, finishing and semi-finished (Fig. 3, k), 8-sided rough with straight (Fig. 3, l) and arc (Fig. 3, m) flanking sections. In the middle part, diamond-shaped 6-sided or trapezoidal (option 2) finishing (fig. 3, n), semi-finished (fig. 3, o) and rough plates with a combined (fig. 3, p) or arc (fig. 3, p) the protruding head. On top, in addition to the 6-sided finishing (Fig. 3, c), semi-finished (Fig. 3, t) and rough plates with a protruding combined (Fig. 3, y) or arc (Fig. 3, f) head, there can be 8-sided (Fig. 3, x), round (Fig. 3, c, w) or 5-sided (Fig. 3, h) are installed. Variants of their installation are possible in various combinations, which are uniquely determined by the size of the plates and the parameters of the teeth of the cutters, but make up the know-how of this invention.

 For mills of medium and large modules, where it is possible to install plates in the plane of the tooth profile for the separate formation of its right and left cutting edges, standard-shaped inserts can be used: three-, four-, five-, hexagonal and others. In this case, preferred are such plates in which the length of the lateral side overlaps the length of the profiling section, respectively, in the middle part, at the leg or head of the tooth, which also uniquely determines their dimensions and installation parameters, but constitutes the know-how of the present invention.

 In FIG. 4 shows mounting options on the rail 1 of the plates 2 and 3, respectively, on the head and leg of the tooth. For this, a support wall 4 is made at the rail leg, repeating the shape of the back surface of the plate pressed against it. Installation of the plate 3 is performed by a pin 5 with a protruding head 6 inserted into an adequate cavity 7 (including a conical, spherical, pyramidal, wedge, segment, cross-shaped or other shape in plan), made on the base of the plate, and the clamp is made by a wedge 8 (which is inserted into the groove 9 between the rails) until it stops between the heel 10 of the pin and the previous plate or, if there is none at the extreme rail, by the supporting surface of the rail and the wedge 11 of increased thickness (Fig. 4, a). In this case, the clamp is provided due to the positive displacement of the axes of the plate hole and the pin mounting hole, and the wedge is fixed with a stopper 12 with bent protrusions (of which the side ones are bent in advance to guide the wedge, and the upper one is bent after jamming). The installation and fastening of the plate 2 on the top of the tooth are similar: in the absence of a compensator, it is pressed directly to the plate mounted on the tooth leg, therefore, their contacting surfaces 13 are made adequate, and the fasteners differ from the previous ones only in the thickness of the wedges 14 and 15. The placement of the fastening elements is possible as from the side of the bases, and from the upper surfaces of the plates (Fig. 4, b). In the presence of between the plates 2 and 3 of the compensator 16 (Fig. 4, b), which serves as a support for both plates, pairs of contact surfaces 17 and 18 are made adequate. When making compensator 16 for roughing and semi-finishing milling cutters for overlapping joints with cutting edges of adjacent plates, its height may be lower than the height of these plates. The remaining fasteners are the same as the previous ones.

 For the case of inserting plates in rough and semi-finished milling cutters into the overlay (Fig. 4, c, d, e), the plates 2 and 3 have protrusions 19, which are inserted into the corresponding cavities 20 of the plate 21. The remaining parameters and fasteners are the same as the previous ones. The plate at the tooth leg can be excluded (Fig. 4, d) when performing the superimposed plate 22, fully profiling the middle part and the tooth leg, which simplifies the fastening elements, and when performing the clamping of the directly superimposed plate 23 (Fig. 4, d) the top plate 2 with a protrusion 24 and their fastening are further simplified. The remaining fasteners differ from the previous ones only in the angle and dimensions of the wedge 8 and groove 9.

In FIG. 5 shows milling cutters assembled from rails with plates placed on them. The rails 1 in the end section are made in the form of flat gear sectors corresponding to the angular pitch ξ _{t of} their installation on the housing 2. For mills with a small angle of elevation of the turns, the rails can be installed in the axial direction (Fig. 5, a) one to one adequate support surfaces 3, which allows to sharply increase their number and simplify the design of the tool. Moreover, the profile of their cutting edges is adjusted accordingly, but the correction method is the know-how of this application. The displacement of the rails along a helical line is accomplished by installing the ends 4 against the stop in a spring 5 inserted into a helical groove 6 having a tooth pitch, and the fastening of the rails can be performed by soldering, gluing or using any of the known mechanical methods, for example, screws. In the case of fastening by soldering, to prevent leakage of solder, instead of a round thrust spring, flat springs 7 (option 2) can be used, installed on both sides in the corresponding screw grooves 8, or cylindrical in the housing 9 (Fig. 5, b) a recess 10 with helical sides 11 corresponding to the course of the turns of the cutter teeth. With insufficient strength of the solder to hold the rails on the supporting surfaces 3, longitudinal and / or transverse grooves or other cavities can be made to fill them with solder, and outside 12, interdental cavities or along the edges of the rails are wound 12 (option 2), which can also be reinforcing element of composite external solder. With sufficient strength for soldering the rails, the use of the mill body can be eliminated (Fig. 5, c), and for their installation along the helix at the ends of the rails, protrusions 13 can be made on opposite sides, or screws 14 with adequate thickness can be installed on the ends of the rails protrusions with heads or plates (option 2).

In FIG. 6 shows the installation and fastening of the rails with an inclination relative to the axis of the cutter, equal to the angle γ _{w of} lifting its helix on the initial cylinder. When this rails 1 are made flat and mounted on a cylindrical body 2 in straight grooves 3 having an inclination γ _w to the axis of the cutter. This design ensures the formation of a hyperboloid producing surface 4, while the profile of the rails completely coincides with the flat initial tool contour, which eliminates the distortion of the cutter for any number of entries (see report: Vitrenko A.N., Vitrenko V.A. et al. "Technology the manufacture of hyperboloid knurls for smoothing the surfaces of parts such as bodies of revolution ", in the book:" Progressive engineering and mechanical engineering ". Abstract of the report of the international scientific-technical conference. Donetsk: DonSTU, 1995, p. 39-40). The fastening of the rails in the grooves can be performed similarly to the previous options, and the fastening of the plates differs only in the increasing thickness of the wedges to compensate for the divergence of the rails when approaching the ends of the hyperboloid surface (Fig. 6, a). However, this drawback can be eliminated (Fig. 6, b) by performing flats 1 on the backs of the rails 1 (after fixing them on the cutter body 2 in the grooves 3) 5, providing a constant width of the grooves for the plates and wedges mounted on the cutter teeth. To exclude in the middle part of the housing sections with a minimum thickness of the partitions between the grooves 3, an annular groove 6 can be made on the housing 2, which further facilitates access for solder. The fastening of the plates on the teeth of the rail can be performed according to any of the options shown in FIG. 4.

 The combination of the above characteristics fully characterizes the proposed parameters of the plates, teeth, racks and mills, which meets the criterion of technical solution. Their execution is not previously known from solutions of the basic level of technology, which meets the criterion of novelty, and does not automatically follow from them, explicitly, which meets the criterion of non-obviousness. Their implementation is possible in modern conditions of real production, since they differ from the basic versions only in the shape of the profile and the installation parameters of non-turning plates, their installation and fastening on the rails, as well as the fastening of the rails themselves, which meets the criterion of industrial applicability. This provides a positive effect, which consists in simplifying the design of cutters and increasing their accuracy and productivity, which improves the technical and economic indicators of their manufacture and operation. Therefore, the proposed technical solutions have all the features of the invention, which consistently develop the previous options.

 Examples of specific performance of the proposed cutters.

For a finishing worm mill processing gears with a module m = 5.5 mm, the width of the tooth on the dividing straight line S _d = 8.81 mm, head height h _a0 = 6.88 mm and legs h _f0 = 6.87 mm, the use of 6-sided inserts with the parameters given in the table provides complete tooth profiling.

 The economic effect of the application of the proposed milling cutters is: 1) to reduce the number of profiling plates, which reduces their consumption; 2) in increasing the number of cutting rails, which increases the resistance of the cutters or the productivity of gear processing; 3) to simplify the design of cutters, which increases the manufacturability of their manufacture and operation.

 At present, experimental designs of worm cutters have been developed, which will be manufactured and tested in 1998 at Kherson Combine Harvesters.

With a decrease in the number of profiling plates by 4/9 and a simultaneous increase in the number of rails by 1/3, the reduction in the consumption of plates will be 1/9 (or 11.1% compared to the original). With the average cost of a set of inserts per 1 mill from 300 to 500 US dollars, this economic effect will be from 33 to 55 $. An additional effect due to a reduction in cutter consumption by 1/3 with an average cost of one cutter from $ 500 to $ 1,000 will be from $ 167 to $ 333. Thus, even without taking into account the economic effect of simplifying the design of cutters, the manufacturability of their production and operation, the total economic effect on one cutter will be
E = (33 ... 55) + (167 ... 333) = 200 ... 388 $.

 With the country's annual demand for such mills up to 2 thousand pieces, the economic effect will be $ 0.4 ... 0.78 million, and taking into account all the advantages of manufacturing and operation, it can be significantly greater.

 The totality of the data confirms the feasibility of widespread use of the proposed cutters.

Claims (17)

 1. A prefabricated worm mill for machining gear products, comprising a housing and rotary non-rotatable cutting inserts mounted along the profiling lines normal to the lateral cutting edges of the teeth through the profiling pole lying at the intersection of the initial straight line with the center axis of the cutter and the product, characterized in that it is equipped with rails on which the said non-rotatable cutting inserts are installed alternately, while the latter have modified sections of the profile, adequate tnye profile of the tooth of the rack, wherein the cutting plates are arranged in the rack tooth profile plane in areas that are bounded by projections profiling lines for medium and an adjacent extreme rack teeth.  2. The cutter according to claim 1, characterized in that the non-rotatable cutting inserts are installed in the plane of the tooth profile at the vertices, in the middle part and on the legs of the teeth of the staff, while on the middle tooth they are installed in the middle part, and on the extreme teeth - on the head and the leg in one plane, with contact with each other on the base surfaces or on the flats made for this.  3. The cutter according to claim 1 or 2, characterized in that it is equipped with a compensator placed between the plates mounted on the head and leg of the tooth of the rail to reduce their size.  4. The cutter according to claim 3, characterized in that the compensators for roughing and semi-finished milling cutters are made cutting, and their profile repeats the profile of this section of the cutter tooth.  5. A milling cutter according to any one of claims 1 to 3, characterized in that the middle and outer teeth with non-rotatable cutting inserts mounted on them for rough and semi-finished milling cutters are placed in reverse order on the rails alternating through one.  6. The milling cutter according to claim 4 or 5, characterized in that non-rotatable cutting inserts having protruding sections for forming allowance cuts on the head and tooth leg of the articles are placed on the tooth leg and head.  7. A milling cutter according to any one of claims 1 to 6, characterized in that trapezoidal or 6-sided modified non-rotatable cutting inserts are installed on the middle teeth of the rails, 6- or 8-, or 9, or 12 are installed on the extreme teeth of the rails at the foot - faceted modified non-sharpened cutting inserts, 5-, or 6-, or 8-, or 12-sided modified non-sharpened cutting inserts, or round, or 5-sided non-sharpened cutting inserts of the correct form are installed at the head.  8. The cutter according to claim 2 or 6, characterized in that for modules that ensure the placement of non-sharpened cutting inserts of the correct shape in the tooth profile plane separately on the right and / or left cutting edges, 3-, or 4-, or 5-, or 6-sided plates, in which the length of the lateral edges overlaps the length of the profiling section, respectively, in the middle of the leg or head of the tooth.  9. The milling cutter according to any one of claims 1 to 4, characterized in that the non-rotatable cutting insert mounted on the tooth tooth leg is pressed against the supporting wall having the shape of its rear surface using a pin with a convex head, which is inserted into the axis a cavity adequate to the head, made on the base or on the upper surface of the non-rotatable cutting insert, and secured by means of a wedge, which is inserted into the groove between the rails as far as it will go into the pin heel and into the previous non-rotatable cutting insert or to replace it at the extreme a supporting surface, and is fixed by the bent protrusions of the stopper worn on the heel of the pin, and the non-rotatable cutting insert mounted and secured to the top of the tooth of the rake is pressed against the rear surface of the non-rotatable cutting insert mounted on the tooth leg or to the compensator installed between these non-rotatable cutting plates.  10. The cutter according to claim 9, characterized in that the middle non-rotatable cutting insert is installed on the non-rotatable cutting inserts of the head and legs according to adequate protrusions and depressions.  11. The cutter according to claim 10, characterized in that the non-rotatable cutting insert mounted on the overlay has a profile of the middle part and legs of the tooth of the rail.  12. The cutter according to claim 11, characterized in that a non-rotatable cutting insert is installed on the head, having a protrusion inserted into an adequate cavity made on the tooth of the rail or on the basis of a superimposed non-rotatable cutting insert, and the superimposed non-rotatable cutting insert is fixed with a pin and a wedge.  13. A milling cutter according to any one of claims 1 to 12, characterized in that the rails are made in the end section in the form of flat gear sectors corresponding to the angular pitch of their placement on the mill body and secured axially when contacting each other with adequate supporting surfaces with the displacement of their teeth along the helix, which is limited by installing the ends of the rails all the way to the spring inserted into the helical groove on the housing, adequate to the helix of the cutter.  14. The cutter according to item 13, wherein the stop springs are made flat and installed in the corresponding screw grooves on both sides of the housing or in the housing for the rails a cylindrical recess with sides that are adequate to the screw cutter tooth line.  15. A milling cutter according to any one of claims 1 to 13, characterized in that its body is fastened from rails, for the installation of which protrusions are made along a helical line, turned to the right at one end of the rail, and to the left at the other relative to the plane of the rail profile, or the ends of the rails installed screws, heads or washers on which are located adequately mentioned protrusions.  16. The mill according to item 13 or 14, characterized in that its rails are mounted with rotation relative to the axis of the mill at an angle equal to the angle of elevation of the helical line in straight grooves made in the housing, forming a hyperboloid bearing surface, which together with rectilinear flat rails forms a hyperboloid producing surface with a longitudinal profile of the rails equal to the flat initial tool contour, and the plates are fastened with wedges with increasing thickness to compensate for the expansion of the gaps between the rails and areas near the ends of the surface of the hyperboloid.  17. The cutter according to clause 16, characterized in that on the backs of the rails mounted on the cutter body, flats are made to ensure a constant width of the grooves for the plates and wedges mounted on the teeth of the cutter.

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