Summary of the invention:
Technical problem to be solved by this invention provides a kind of over-long precise mortise joint rack, and it can reduce the tooth pitch deviation of joint, guarantees that accurate length apart from the tooth bar transmission quality, improves the bearing capacity of joint.
The present invention also will provide a kind of method of making over-long precise mortise joint rack.
Thinking of the present invention is, significant surfaces to decision rack segments shaped positions such as the flank of tooth of the vital part joggle rack segments that constitutes rack elements, tongue-and-groove, tenon, carrying reference levels adopts the disposable clamping of same locating basis, use the numerical control electric spark linear cutting equipment, cut out and the corresponding to accurate slit of rack segments shape track, carry out the shaping processing of significant surfaces such as tooth portion, tongue-and-groove, tenon, carrying reference level thus.
In order to address the above problem, the present invention by the following technical solutions:
A kind of over-long precise mortise joint rack of the present invention, it is combined by two or more joggle rack segments 1, each joggle rack segments comprises tooth row 2, fixing screw hole 3, positioning pin hole 4, tooth bar end 5, tongue-and-groove 6 tenons 7 and bar shaped body 8 structures, described tongue-and-groove 6 is opened on the end 5 of rack segments near middle position, the position that the other end that described tenon 7 is located at rack segments and tongue-and-groove 6 are corresponding, under the assembled state, described tenon 7 is formed the nested joggle structure that is connected with the tongue-and-groove 6 on adjacent another rack segments, both ends of the surface and tenon and tongue-and-groove surface form the surface of contact that closely links up, and constitute the accurate accurate combination of two rack segments thus.
The direction of described tongue-and-groove 6 is vertical with the length direction of bar shaped body 8, and parallel with the teeth groove direction.
The sectional shape of described tenon 7 is identical with the sectional shape of described tongue-and-groove 6.
Described tenon 7 and tongue-and-groove 6 comprise head and neck respectively, and the head width dimension D of described tenon 7 is greater than its neck width size T; The reference point O of described tongue-and-groove 6 and tenon 7 cross section figures equates apart from B to the reference point O's ' of profile of tooth.
The fiting property of described joggle can be designed as transition fit or interference fit.
The seamed edge of described tenon 7 is a chamfer shape.
A kind of method of making above-mentioned over-long precise mortise joint rack, its step comprises:
(1) rough forging step, blank is the rectangular slab bulk, thickness is pressed the tooth bar width and is set, the length of blank adds tenon minister Du Jia 30-50 millimeter clamping amount, width dimensions according to arranging 1 to n rack segments along the rack segments short transverse for the rack segments effective length, and consider that wire cut electric discharge machine clamping allowance and track profile set at interval, be that n rack segments height adds n-1 track profile 2-10 millimeter at interval, add clamping allowance 30-50 millimeter again, the short transverse of described rack segments is consistent with tooth depth; The rack segments width direction is consistent with facewidth direction.
(2) early stage process step, comprise the big plane of roughing and fixing screw hole, pin hole and threading hole, threading hole is a kind of cutting track initial position that is located at, and is used for the through hole by electrode wire, it also claims auxiliary hole).
(3) heat treatment step, to be processed of tooth bar after adopting heat treating device such as electric furnace to above-mentioned processing carries out quenching heat treatment, improves workpiece hardness, makes it reach HRC32-42.
(4) grinding plane step adopts surface grinding machine that grinding is carried out on the big plane of heat treated workpiece, makes it to reach dimensional accuracy 0.05mm, planeness 0.03mm, surface roughness Ra 3.2 μ m grades.
(5) establishment numerical control electric spark wire cutting program step is according to the numerical control electric spark wire cutting program of the programming standardize organization rack segments of the cutting track that shape and size determine of rack segments profile and employed NC wirecut EDM machine.
(6) location clamps to be processed step, working specification with reference to equipment, to digital control wire-electrode cutting equipment, adopt to be processed clamping universal fixture to guarantee that to be processed big plane is parallel with table top and the significant surfaces of decision tooth bar shaped positions such as the flank of tooth, tongue-and-groove, tenon, carrying reference level adopted the disposable clamping of same locating basis.
(7) numerical control electric spark line cutting step, at first determine the initial position of cutting track, wear electrode wire then, start-up routine, thereafter, by electrode wire discharge generation cutting slit, the movement locus of the worktable that computerizeds control cuts out and the corresponding to accurate slit of tooth bar shape track, carry out the automatic cutting of significant surfaces such as tooth portion, tongue-and-groove, tenon thus, thereby finish the shape processing of tooth bar.
(8) tenon edge chamfering step is utilized electronic or pneumatic grinding head carries out chamfered to the tenon rib.
(9) installation step, for being the mounting type of junction plane and supporting plane with mutually perpendicular tooth bar side and tooth bar bottom surface, only a positioning pin hole to a rack segments positions on total length, then, be fixed on the machine support junction plane with set screw, guarantee simultaneously that surface corresponding with supporting member, tooth bar bottom surface is pasted and, again all the other joggle rack segments piecemeal by light pressing end-to-end, screw, finish assembling, for only with the mounting type of tooth bar side as junction plane, need be at whole two positioning pin hole installing and locating pins of rack segments.
Among the present invention, described rack elements overall length dimension equals all rack segments length dimension sums, and described rack segments length dimension equals the integral multiple of pitch of teeth.
The advantage that the present invention compared with prior art has:
Because the disposable clamping processing of same locating basis is adopted in the processing of described joggle rack segments, can obtain the best mutual alignment precision between the significant surfaces thus.So positioning error that does not have the conversion of classical production process benchmark and repeatedly be installed and cause.
Because this processing method is no cutting force processing, therefore do not exist in the traditional diamond-making technique because the error that cutting force produces.
Because utilization digital control wire-electrode cutting technology utilizes its cutting gap compensation function can control the size deviation of tongue-and-groove and tenon, therefore can make the contact position form reasonable supporting clearance, as transition fit, interference fit etc.
Because over-long precise mortise joint rack of the present invention has the joggle structure, and adopt the numerical control electric spark line cutting technology to process, therefore can obtain higher workpiece accuracy of manufacturing, and the manufacturability that is linked and packed is better, reduce the tooth pitch deviation of joint effectively, improve the bearing capacity of joint, guarantee accurate long apart from the tooth bar transmission quality.In addition, manufacture method of the present invention is not subjected to the restriction of workpiece material hardness, can make whole high hardness rack elements, and the precision of rack elements and bearing capacity are kept for a long time.
Embodiment
Specific embodiments of the present invention is described in detail with reference to the accompanying drawings.
Fig. 1 is an over-long precise mortise joint rack mode of execution structural representation of the present invention, Fig. 2 is a joggle rack segments mode of execution organigram of the present invention, Fig. 3 is the tenon groove structure schematic representation of joggle rack segments mode of execution of the present invention, Fig. 4 is the tenon structural representation of joggle rack segments mode of execution of the present invention, Fig. 5 is the joggle local structure stereogram of over-long precise mortise joint rack mode of execution of the present invention, and Fig. 6 is the joggle partial circle arc section curve and the coupled condition structural representation of over-long precise mortise joint rack mode of execution of the present invention.
Referring to Fig. 1, Fig. 2, over-long precise mortise joint rack of the present invention by two or more joggle rack segments 1, constitute.Wherein each joggle rack segments has tooth row 2, fixing screw hole 3, positioning pin hole 4, tooth bar end 5, tongue-and-groove 6, tenon 7, bar shaped body 8 formations.Described joggle rack segments 1 is provided with positioning pin hole 4 near end position, realizes location to described tooth bar by this positioning pin hole 4 and locating stud.In addition, be respectively equipped with the fixing screw hole 3 that stationary rack is used in the inboard of described positioning pin hole 4, described joggle rack segments 1 be fixed on the supporting member of tooth bar by set screw being inserted this fixing screw hole 3.In addition, on the end 5 of above-mentioned joggle rack segments 1, be provided with tongue-and-groove 6 near middle position, the position that the other end that described tenon 7 is located at rack segments and tongue-and-groove 6 are corresponding.The joggle that constitutes embedded structure by the tongue-and-groove 6 and the tenon 7 of adjacent two rack segments.
In addition, the direction of described tongue-and-groove 6 is vertical with the length direction of bar shaped body 8, and the cross-section curve shape of tenon 7 is identical with the cross-section curve shape of tongue-and-groove 6, can be continuous arc, as shown in Figure 3, Figure 4, also can be other shape, as rectangle, swallow-tail form etc., as Fig. 7, Fig. 8.D is the head width size of joggle cross section; T is the neck width size of joggle cross section; O is the reference point of joggle cross section figure; O ' is the reference point of profile of tooth; B is the distance of joggle cross section figure reference point O to profile of tooth reference point O '; P is a tooth pitch.
The size relationship of the size of above-mentioned tenon 7 and tongue-and-groove 6 is, the head width dimension D of described tenon 7 is greater than the neck width size T of described tenon, and the reference point O of the cross section figure of described tongue-and-groove 6 and described tenon 7 equates apart from size B with the reference point O's ' of profile of tooth.
The mode of execution of over-long precise mortise joint rack of the present invention is made of n section joggle rack segments, the effective length of each section be Lk (k=1,2 ..., n), its total length L t equals each rack segments effective length sum, as shown in Figure 1.The effective length Lk of joggle rack segments equals the tooth pitch P of tooth bar and the product of the tooth bar number of teeth, and the number of teeth must be an integer.
In addition, chamfer shape is made at the knuckle place of described tenon 7, is beneficial to assembling.
Fig. 5 is the joggle partial perspective view of coupled condition of the mode of execution of over-long precise mortise joint rack of the present invention.When combine and assemble, after in the tongue-and-groove 6 that tenon 7 is inserted adjacent rack, the tenon 7 of adjacent two rack segments and tongue-and-groove 6 form the joggle of embedded structure.This joggle can realize connecting the abundant contact on surface, and distribution of contact is reasonable.
In addition, the direction of described tongue-and-groove 6 is vertical with the length direction of bar shaped body 8, and tenon 7 is chimeric with the shape convex-concave of tongue-and-groove 6.
Fig. 7 is the joggle local moment tee section curve and the coupled condition structural representation of over-long precise mortise joint rack mode of execution of the present invention, and as shown in Figure 7, described joggle cross-section curve is the rectangle build-up curve.
Fig. 8 is local swallow-tail form cross section curve of the joggle of over-long precise mortise joint rack mode of execution of the present invention and coupled condition structural representation, and as shown in Figure 8, described joggle cross-section curve is the swallow-tail form curve.
In Fig. 6, Fig. 7, Fig. 8, D is the head dimensions of joggle cross section; T is the neck size of cross section; O is the reference point of cross section figure; O ' is the reference point of profile of tooth; B is the distance of cross section figure reference point O to profile of tooth reference point O '; P is a tooth pitch.
Because the accuracy of manufacturing of this tooth bar is had relatively high expectations.Thus, after tenon 7 and tongue-and-groove 6 be combined into embedded structure, can be so that the tooth pitch precision of whole assembled rack be higher, when adopting circular section, pitch error can reach 0.010-0.028 millimeter, thereby guarantees that this gear rack transmission pays and have higher precision.
Fig. 9 is the driving mechanism and the work loads schematic representation of over-long precise mortise joint rack mode of execution of the present invention.
Figure 10 forms long rack gear and work loads schematic representation with the short tooth bar of existing conventional art.
As shown in Figure 9, the 9th, over-long precise mortise joint rack, after any two-phase neighbour's joggle rack segments assembling, its joggle position forms the face contact that closely links up, and constitutes the accurately nested closely combination of two adjacent joggle rack segments.When work was paid in the transmission that gear 14 and this tooth bar 9 constitute, wherein a rack segments and gear 14 meshed, and bore the load from gear, as the commentaries on classics torch symbol 13 of arrow direction.Because joggle can transmit tension compression bidirectional load, therefore load is delivered to other each section tooth bar by a series of joggles, and be delivered on the supporting member by the fastening rubbing action of all set screws 10 and the shearing resistance effect of positioning dowel 11, load is rationally distributed.
In Fig. 9, Figure 10, two-way outer arrow 12 is the tensile stress symbol, and the expression tensile stress distributes, and two-way interior arrow 15 is the pressure stress symbol, and the expression pressure stress distributes.Obviously, as shown in Figure 9, be the boundary with the loading point of gear, in half tensile stress that distributing of tooth bar total length, and second half pressure stress that distributing.
As shown in figure 10,16 are the short tooth bar of existing conventional art, and Δ be the gap of assembling back existence between the end of its adjacent rack.Because the clearance delta that exists between the end of its each rack segments, when therefore working one section tooth bar bearing load can only be arranged, can not form effective loading transfer, suffered load can only be delivered on the supporting member by the fastening rubbing action of the set screw of this section tooth bar and the shearing resistance effect of pin, and this stress distribution mode can cause stress to be concentrated and stress mutation.
Comparison diagram 9 shows that with Figure 10 over-long precise mortise joint rack supporting effect of the present invention and whole tooth bar are more approaching.And, its better effects if when the joggle head is prestressing force assembling character.
In addition, when assembling over-long precise mortise joint rack of the present invention,, get final product so only use a locating stud to position because tenon insertion tongue-and-groove can guarantee the correct relation between each rack segments.And do not need each rack segments is positioned, therefore assemble simple and convenient and lower to operator's technical ability requirement.
Because joggle rack segments 1 structure of the present invention is complicated, shape and position accuracy demand are higher, and material hardness height, and therefore traditional general cutting apparatus is not suitable for making joggle rack segments of the present invention.For this reason, the invention provides a kind of manufacture method that adopts the numerical control electric spark wire cutting method to process, referring to Figure 11.
Figure 11 is the processing method schematic representation that adopts NC wirecut EDM machine processing joggle rack segments of the present invention.Among Figure 11,17 be to be processed, 18 for electrode wire, 19 for cutting track, arrow points is the direction of feed of electrode wire 18.
The manufacture method of above-mentioned joggle rack segments comprises:
(1) rough forging step.Blank is the square shape, and thickness is pressed the tooth bar width and set, and the length of blank, width be according to can arranging a plurality of rack segments, and considers that spark-erosion wire cutting equipment clamping allowance sets.
(2) early stage process step.Comprise roughing of big plane and fixing screw hole, positioning dowel hole and threading hole processing.
(3) heat treatment step.To be processed after adopting heat treating device such as electric furnace to above-mentioned processing is carried out quenching heat treatment, improves workpiece hardness, makes it reach HRC32-42.
(4) grinding plane step.Adopt surface grinding machine that grinding is carried out on the big plane of heat treated workpiece, make it to reach dimensional accuracy, planeness, the roughness grade of drawing requirement, for example 0.05mm, 0.03mm, Ra3.2 μ m.
(5) establishment numerical control electric spark wire cutting program step.Numerical control electric spark wire cutting program according to the tongue-and-groove surface of diagram shape of cutting track 19 and parameter establishment tooth bar, tenon surface, tooth working surface, carrying bottom surface.During programming, to carry out the joint-cutting compensation between the centrode of electrospark electrode line 18 and the work piece cut track 19 according to the diameter of electrospark electrode line 18.And program will meet the programming standard of the equipment that uses.
(6) location clamps to be processed step.In the time of on the worktable of to be processed 17 clamping, adopt universal fixture to guarantee that to be processed 17 big plane is parallel with table top at NC wirecut EDM machine.The edge that the anchor clamps pressing plate is fixing to be processed 17, and must not interfere cut coverage.In addition, impacting force will suit, and must not cause workpiece deformation.
(7) numerical control electric spark line cutting step.At first determine the initial position of cutting track 19, wear electrospark electrode line 18 then, thereafter, make to be processed 17 relative electrospark electrode line 18 carry out feeding according to cutting track shown in Figure 11 19, realize 18 17 the automatic cuttings to machined part of electrospark electrode line, thereby finish tongue-and-groove surface, tenon surface, the tooth working surface of tooth bar, the numerical control electric spark line cutting process of carrying bottom surface.Wherein, the cutting process parameter should satisfy requirement on machining accuracy such as device therefor standard and part roughness.
(8) tenon edge chamfering step.Utilize electronic or pneumatic grinding head etc. carried out chamfered to the tenon seamed edge, becomes 0.8 * 45 ° chamfering.
(9) installation step.Multistage joggle rack segments end-to-end by gently compressing into the row combination, is only assembled a locating stud and gets final product on total length.Then, be fixed on the mechanical bearings junction plane, guarantee tooth bar bottom surface and supporting member relevant surfaces even contact simultaneously with set screw.
According to as can be known above-mentioned, the advantage of over-long precise mortise joint rack of the present invention and manufacture method thereof is:
A. two adjacent teeth bar section joint can obtain very high tooth pitch precision.The tooth pitch deviation of joint depends on the accuracy of manufacturing of joggle, the accurate digital control line cutting manufacture method processing tongue-and-groove and the tenon of uses advanced, and after assembling, pitch error can reach 0.010-0.028 millimeter scope.And this method is that main surface once is installed and finishes processing under the no cutting force condition, can not produce error because of cutting force and machining benchmark conversion.Thus, more easily obtain the overall tooth pitch precision of rack elements, and do not rely on the assembly method and the condition of tooth bar and supporting member.
The fiting property of described joggle can design in advance in addition, is fabricated to transition fit or interference fit as required, thereby realizes the prestressing force assembling, makes this joint bear the function that still has maintenance tooth pitch precision under the complex load situation.Therefore can avoid traditional tooth bar to be difficult for the problem that guarantees because of its joint pitch error.
B. tooth bar integrated carrying ability is strong.After the combination of two joggle rack segments, its joggle position forms the surface of contact that closely links up, and constitutes the accurately nested closely combination of two adjacent teeth bar.Because joggle can transmit tension compression bidirectional load, so load is delivered to other each section tooth bar by a series of joggles, and is delivered on the supporting member by the fastening rubbing action of all set screws and the shearing resistance effect of pin, guarantees the reasonable distribution of load.Therefore this tooth bar can bear big load.
C. assembly process process is good.The tenon tongue-and-groove of packing into has promptly guaranteed correct relation between two sections tooth bars.Do not need special Method and kit for.Technical ability to assembling work condition and operator requires lower.Property easy to assembly is obvious.
D. tooth bar hardness height.Over-long precise mortise joint rack of the present invention is owing to adopt the cutting of numerical control electric spark line to can be designed as the high hardness tooth bar.Thereby precision stability is good, wear-resistant, and the life-span is long.
E. manufacture process is simple.Joggle method for producing rack of the present invention is compared with traditional tooth bar processing method, and it uses process equipment to make than being easier to less.
In addition, aspect work efficiency, because the metal resection rate of line cutting is far below the metal resection rate of milling, grinding, but the metal removal in this method cutting slit is very little, and simplify tooth bar significantly and make overall process, therefore, effect is obvious in the long precise tooth bar of single and mini-batch production is made.