Roller designs the analytic method of translating cam contour curve when pressing cosine rule direct acting
Technical field
The present invention relates to a kind of method for designing cam profile curve, and in particular to a kind of roller makees straight line by cosine rule
The analytic method of translating cam contour curve is designed during reciprocating motion, belongs to cam design and processing technique field.
Background technology
Cam is the component for having specific curves profile, and the mechanism containing cam is referred to as cam mechanism.Cam mechanism is in machine
Tool engineering field is widely used, and its great advantage is that driven member can be made to realize various complicated movement needs, and response quickly.
But for conventional sophisticated driven member, flat-face follower, due to being to contact or line between cam profile curve and driven member
The contact area of the higher pair of contact, cam contour and driven member is small, so contact position pressure is big, easy to wear.In order to reduce friction
Abrasion, installing a roller in driven member end turns into roller follower, becomes the sliding friction between driven member and cam
Rolling friction, preferably solves the wear problem of cam mechanism, the probability for being in contact fatigue failure is greatly reduced.
" roller follower --- the translating cam " mechanism being widely used in various mechanical devices, it is a kind of typical flat
Face cam mechanism.There is one-to-one close between the characteristics of motion of roller follower and the shape of translating cam contour curve
System, in engineering practice, the characteristics of motion of roller follower is typically what is determined by the requirement of translating cam, translating cam wheel
The foundation of wide curvilinear equation is to ensure that roller follower meets desired movement rule and then designs that of good performance " roller is driven
The most important condition of part --- translating cam " mechanism.
Cosinusoidal motion rule is a kind of common characteristics of motion of cam follower, existing machinery design teaching material and correlation
In handbook, the derivation introduction of profile of plate cam curvilinear equation is many when being moved for sophisticated push rod driven member by cosine rule,
But what kind of method to design the profile of translating cam when making straight reciprocating motion by cosine rule for roller follower with
Curve is then seldom related to, and designer obtains the profile of such translating cam song frequently with manual plotting by described point and fitting
Line, because manual plotting error is larger and wastes time and energy, low speed translating cam and unessential occasion are only used for, is hindered
The development and popularization and application of " direct acting roller follower --- translating cam " mechanism.
The content of the invention
For overcome the deficiencies in the prior art, the invention provides a kind of design process is directly perceived, computational efficiency is high and accurate
Roller the analytic method of translating cam contour curve is designed when pressing cosine rule direct acting, to solve to design such translating cam at present
Contour curve lacks the analytic method that may be referred to or manual plotting is time-consuming more by rule of thumb and cam profile curve that try to achieve owes smooth
It is not gentle, motion distortion be present, the problems such as cam cutting precision is difficult to ensure that.
The purpose of the present invention is achieved through the following technical solutions:
A kind of roller designs the analytic method of translating cam contour curve when pressing cosine rule direct acting, the roller is by cosine
Rule makees the driven member of straight reciprocating motion, and the translating cam refers to the cam that constant speed movement is matched and made with the roller;Work
When roller and cam contour contact point be consistently equal to radius of roller to the distance in the roller center of circle, the displacement function of roller is defined as ought
When cam translates x, the roller center of circle rises displacement y from initial position, i.e. translating cam contour curve can state cam position as
Move x function;The translating cam contour curve that the analytic method is formed includes ascent stage cosine curve EN and NF, horizontal segment straight line
FFf, descending branch cosine curve FfNfWith NfEf, translating cam contour curve comprises the following steps that described in Analytical Design:
1) basic parameter of the roller and translating cam is drafted according to design objective requirement:Radius of roller r, roller lift
H, the speed V of constant speed movement cam, translating cam corresponding with roller lift h displacement L1, with horizontal segment straight line FFfIt is corresponding
The displacement L of translating cam2;
2) it is origin O, the direction opposite with cam moving direction for x side using the starting rising point in the center of circle of the roller
To, with cam moving direction vertical and upwardly direction be y directions establish coordinate system, set by the requirement of translating cam mechanism
Roller is determined by acceleration equation during cosine rule direct acting:
Wherein, H is the characteristic parameter for the shape for determining translating cam contour curve, and a (x) is that roller makees straight reciprocating motion
When acceleration;
3) according to the roller direct acting acceleration cosine rule of setting, according to the movement velocity of roller without mutation, translating cam
Contour curve is smooth continuous and in the absence of the principle of cusp and motion distortion, simultaneous equations (1) and (2):
Obtain determining characteristic parameter H, more than the ascent stage of translating cam contour curve of the shape of translating cam contour curve
The abscissa x of chord curve EN and NF tie pointN;
4) the ascent stage cosine curve, horizontal segment straight line, descending branch cosine curve of translating cam contour curve are established respectively
Mathematical equation:
1. establishing the ascent stage cosine curve EN of translating cam contour curve, its math equation is:
2. establishing the ascent stage cosine curve NF of translating cam contour curve, its math equation is:
3. establish the horizontal segment straight line FF of translating cam contour curvef, its math equation is:
4. establish the descending branch cosine curve F of translating cam contour curvefNf, its math equation is:
5. establish the descending branch cosine curve N of translating cam contour curvefEf, its math equation is:
5) by the ascent stage cosine curve EN drawn according to above-mentioned math equation and NF, horizontal segment straight line FFf, more than descending branch
Chord curve FfNfWith NfEfIt is smoothly connected, obtains the profile of translating cam when roller makees straight reciprocating motion by cosine rule
Curve.
It is that " direct acting roller follower --- translating cam " mechanism design most critical is also most to establish cam profile curve equation
A difficult step, the beneficial effects of the invention are as follows:
(1) as long as establishing the contour curve equation of translating cam according to the step, roller can be achieved with predetermined by remaining
String rule makees straight reciprocating motion, substantially reduces the construction cycle, improves design accuracy and design efficiency, while is " direct acting
The Parametric designing of roller follower --- translating cam " mechanism provide reliable theoretical foundation and it is efficient and convenient, be easy to grasp
Design method.
(2) be easy to Matlab or other programming languages powerful drawing function come quickly and accurately draw movement it is convex
Visual and clear contour curve is taken turns, and gained translating cam contour curve is still smooth continuous gentle in slope variation, is rising
The junction contour curve of two strokes of journey and backhaul is not in the phenomenon for disconnecting or intersecting, in the absence of motion distortion.Rolling
When son makees straight reciprocating motion by cosine rule, the movement velocity of roller eliminates the rigid shock of cam mechanism, dropped without mutation
The low vibration and noise of movement parts, improve the dynamic property and its service life of translating cam mechanism.
(3) according to the universal equation of translating cam contour curve provided by the invention, it is convex that CNC milling machine milling can be provided
Track of tool center sport when wheel or cam grainder grinding cam, so as to process the guaranteed movement of precision, quality
Cam, processing cost is reduced, improve the effect that " direct acting roller follower --- translating cam " mechanism uses CAD/CAM technologies
Benefit.
Brief description of the drawings
Fig. 1 is stream of the roller of the present invention by the analytic method embodiment that translating cam contour curve is designed during cosine rule direct acting
Cheng Tu;
Fig. 2 is that the translating cam contour curve that analytic method of the present invention is formed and matched roller press cosine rule
Relation schematic diagram during direct acting between roller deferent;
Fig. 3 is that the movement that the analytic method of translating cam contour curve is formed is designed when roller of the present invention presses cosine rule direct acting
Cam profile structural representation.
In figure:EN and NF is ascent stage cosine curve, FFfFor horizontal segment straight line, FfNfWith NfEfFor descending branch cosine curve,
Rf represents roller, and r is radius of roller, and h is roller lift, L1For cam displacement corresponding with roller lift h, L2For with horizontal segment
Straight line FFfCorresponding cam displacement, ENFFfNfEfFor the contour curve of translating cam, OMTTfMfOfMoved along for roller is cylindrical
When the contour curve of cam rolls, the track in the roller center of circle.
Embodiment
Below in conjunction with the accompanying drawings, the implementation process of present invention design translating cam contour curve analytic method is described in detail.
1) activation system;
2) according to design objective or production scene working condition requirement, " direct acting roller follower --- translating cam " mechanism is drafted
Basic parameter:Radius of roller r, roller lift h, the translational speed V of constant speed movement cam, corresponding with roller lift h move
The displacement L of cam1, with horizontal segment straight line FFfThe displacement L of corresponding translating cam2;
3) be by origin O, the direction opposite with cam moving direction of the starting rising point in the roller center of circle x directions, with it is convex
Wheel moving direction is vertical and upwardly direction is that coordinate system is established in y directions, and roller is set by the requirement of translating cam mechanism
It is by acceleration equation during cosine rule direct acting:
Wherein, H is the characteristic parameter for determining translating cam contour curve shape, when a (x) is that roller makees straight reciprocating motion
Acceleration;
4) according to the roller direct acting acceleration cosine rule of setting, motion analysis is carried out to the translating cam mechanism, taken into account
Translating cam contour curve is smooth continuous and cusp, intersection and motion distortion phenomenon is not present, while considers the motion speed of roller
The requirement do not undergone mutation is spent, simultaneous equations (1) are tried to achieve with (2) to be determined the characteristic parameter H of translating cam contour curve shape, moves
The abscissa x of moving cam contour curve ascent stage cosine curve EN and NF tie pointN:
5) mathematical equation corresponding with ascent stage of translating cam contour curve, horizontal segment, descending branch is established respectively:
1. the ascent stage cosine curve EN of translating cam contour curve math equation is established according to formula (3):
2. the ascent stage cosine curve NF of translating cam contour curve math equation is established according to formula (4):
3. the horizontal segment straight line FF of translating cam contour curve is established according to formula (5)fMath equation:
4. the descending branch cosine curve F of translating cam contour curve is established according to formula (6)fNfMath equation:
5. the descending branch cosine curve N of translating cam contour curve is established according to formula (7)fEfMath equation:
6) by the ascent stage cosine curve EN drawn according to above-mentioned equation and NF, horizontal segment straight line FFf, descending branch cosine it is bent
Line FfNfWith NfEfIt is smoothly connected, roller in " direct acting roller follower --- translating cam " mechanism can be obtained and advised by cosine
Rule makees the contour curve of translating cam during straight reciprocating motion, the work of translating cam contour curve described in completion Analytical Design
Make.
It is specific below by one in order to embody the simple and easy of present invention design translating cam contour curve analytic method
Design process is illustrated.
Now require the contour curve of translating cam in one " direct acting roller follower --- translating cam " mechanism of design, it is known that
Roller follower makees straight reciprocating motion in vertical direction by the motion feature of " rising -- stopping -- to return ", and cam is horizontal positioned and it is moved
Dynamic direction is turned left, roller it is past, return stroke and obey cosine function rule.
First:Required according to design objective and user, determine radius of roller r=15mm, roller lift h=40mm, constant speed
The speed V=35mm/s of translating cam, cam displacement L corresponding with roller lift h1=120mm, with horizontal segment straight line FFfIt is corresponding
Cam displacement L2=30mm.
The analytic method of the translating cam contour curve is designed, can be realized by following steps:
1) the above-mentioned known parameters value of roller, translating cam is substituted into equation (1) and (2), obtained:
The two equations of simultaneous solution obtain:The characteristic parameter H=21.08mm of decision translating cam contour curve shape,
The abscissa x of translating cam contour curve ascent stage cosine curve EN and NF tie pointN=63.61mm;
2) math equation that translating cam contour curve ascent stage cosine curve EN is obtained according to formula (3) is:
3) math equation that translating cam contour curve ascent stage cosine curve NF is obtained by formula (4) is:
4) translating cam contour curve horizontal segment straight line FF is obtained according to formula (5)fMath equation be:
Now, direct acting roller follower enters remote dormant state.
5) translating cam contour curve descending branch cosine curve F is obtained by formula (6)fNfMath equation be:
6) translating cam contour curve descending branch cosine curve N is obtained by formula (7)fEfMath equation be:
7) according to the separate equation tried to achieve above, it is straight that ascent stage cosine curve EN and NF, horizontal segment can be drawn out respectively
Line FFf, descending branch cosine curve FfNfWith NfEf, these linear light slips are got up, roller can be obtained and made directly by cosine rule
The contour curve of translating cam when line moves back and forth, so as to terminate " direct acting roller follower --- translating cam " mechanism design
The process of the analytic method of translating cam contour curve.
The analytic method of design translating cam contour curve of the present invention is smooth gentle according to translating cam contour curve
Continuously and in the absence of cusp, intersection and motion distortion phenomenon, the movement velocity of roller translating cam is established without requirements such as mutation
The universal equation of contour curve.Although having carried out described above to the present invention with reference to accompanying drawing, the invention is not limited in upper
The embodiment stated, above-mentioned embodiment is only schematical, rather than restricted.Heretofore described one
As principle can be realized in other embodiments without departing from the spirit of the invention.Therefore, it is every using the present invention
Design some simple deduction or replace, the modification made, should all be considered as belonging within protection scope of the present invention.