# GB/T 1800.3 limit and cooperate a foundation

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3-1998 " the limit and cooperate a foundation the 3rd part: Standard public errand and basic error numerical value are expressed " made clear and specific provision to standard public errand and basic error. New GB GB/T 1800.

3 stipulated basic measure comes the standard public errand of 3150mm, basic measure reachs two appendices to the basic error of 3150mm. Appendix A gave out the computational method of public errand of the numerical value of standard public errand of section of the origin of standard public errand and basic error, dimension, IT01 and IT0, standard and deviation and its are numeric long make an appointment with regulation to wait; Appendix B gave out standard application citing. GB/T 1800.

3 with old GB GB 1800-79 " tolerancepublic errand and cooperate topical standard public errand and basic error " in corresponding share photograph is compared, outside the modification that divided editor sex, there basically is the following change on content; Cancel the standard public errand of the IT01 of grade of standard public errand that basic measure reachs 3150mm in old GB text and IT0 is numeric. Considering the effective demand in production, new GB gave out in the appendix basic measure is mixed to the IT01 of 500mm the standard public errand of IT0 is numeric. Will old GB is basic the regulation of dimension section, in the appendix that included new GB. Basic measure is more than new old GB the tolerancepublic errand numerical value of the IT4 of grade of standard public errand to 3150mm and IT5 has 500mm 6 point are different. New GB increased applied citing of the standard. GB/T 1800.

3 outside applying to cylinder to reach cylindrical the dimension of smooth workpiece. What should point out is, although the computational method of standard public errand and basic error gives out in the standard, but the numerical value that expresses a kind in the standard when application is authority. The standard noncombatant duty that new standard of series of 1 standard public errand sets is mixed by grade of standard public errand numerical value of standard public errand is formed. Tolerancepublic errand numerical value is a basis after coefficient of grade of factor of standard public errand, public errand and classics of basic measure section are calculated, get. New GB of grade of standard public errand comes in basic measure IT18 of ～ of IT01, IT0, IT1 set inside 500mm in all grade of 20 standards public errand, 500mm is more than to come in basic measure IT1 ～ IT18 set inside 3150mm in all grade of 18 standards public errand. Come from IT01 IT18, grade is ordinal reduce, and numerical value of corresponding standard public errand is ordinal increase. New GB sets and differentiate the purpose of tolerancepublic errand grade is: To simplify and unite the requirement to tolerancepublic errand. Basic measure mixes to the origin grade IT01 of the standard public errand of 500mm, IT0 the standard public errand of IT1 is numeric (with µm plan) calculate by following formula: IT01: 0.

3+0.

008DIT0: 0.

5+0.

012DIT1: 0.

8+0.

In the type on 020D, d is the from beginning to end in section of the each dimension in the watch the geometrical average of two dimension, with Mm plan. The numerical value of standard public errand of grade IT2, IT3 and IT4 is not according to some formula is begged those who go out, press geometrical progression to increase by degrees the rule decides roughly between the numerical value of IT1 and IT5 however. Grade IT5 is the function of I of factor of standard public errand to the numerical value of standard public errand of IT8, by place of standard appendix A the row is calculated formulary computation, of classics regulation long get after the circle is full about. Factor of standard public errand is the main unit of certain level public errand, it is the base that establishs numerical value of standard public errand to express. It is to build the base in practice, pass technical trial and statistical analysis, after finding out spare parts treatment and the rule that measure an error to change along with basic measure from which, decide. Basic measure calculates by next type to the I of factor of standard public errand of 500mm: I=0.

453D+0.

In 001D type: I with µm plan; D is basic measure paragraph geometrical average, mm. Formula basically reflects the machining error of workpiece the first times medium; The 2nd is used at compensation and basic measure to become the error of direct ratio, advocate if do not stabilize what with deviate fiducial temperature place causes as a result of the temperature when measuring,measure an error, and gauge is out of shape the error. Become actually basic measure very hour, the 2nd proportion that holds is very small, this pattern is so similar at cubic parabola relation. Watch grade IT4, IT5 is new numerical value of old public errand is comparative and basic IT4IT5 of grade of public errand of dimension Mm standard is new old new old be more than to µm500630- - 3230630800- - 363580010002829- - 10001250333447461250160039405554160020004648- - 20002500555778772500315068699693 basic measure are more than 500mm to come to the origin grade IT1 of the standard public errand of 3150mm the function that the numerical value of standard public errand of IT18 is I of factor of standard public errand, by place of standard appendix A the row is calculated formulary computation, of classics regulation long get after the circle is full about. I of factor of standard public errand calculates by next type: I=0.

45D1/3+0.

In 001D type: I with µm plan; D is basic measure paragraph geometrical average, mm. To large size, relative to character, the effect that measures an error is bigger, especially the impact of temperature is very big, follow basic measure because of the error that temperature change causes increase show linear concern, be opposite so the factor of standard public errand of large size (I) uses linear relation to calculate. The specification that to basic measure the numerical value of standard public errand to 3150mm expresses presses afore-mentioned methods, the tolerancepublic errand numerical value of grade of each standard public errand inside the basic measure section that computation gives sees be expressed in the standard 1. Those who want a specification is, watch 1 in numerical value of place line common difference is not abide by completely long make an appointment with regulation, distributing according to tolerancepublic errand numerical value and having a few among them decide. When basic measure is less than in watch of numerical value of standard public errand or be equal to 1mm, off grade IT4 comes IT18; Basic measure is more than 500mm, grade IT1 is try out to the numerical value of standard public errand of IT5. Because grade IT01 is mixed,IT0 is used rarely in industry, consequently new GB includes an appendix the numerical value of standard public errand of this two grade in, basic measure also arrives only 500mm. Public errand of the standard in the watch is numeric, the rule since grade IT6 is: Every add 5 grade, standard public errand increases to 10 times. For example dimension paragraph to 3mm, the tolerancepublic errand numerical value of grade IT7 is 10µm, grade is added to IT12 when, tolerancepublic errand numerical value is 100µm. In the watch of numerical value of standard public errand of new old GB, basic measure is more than 500mm, the public errand of grade IT4, IT5 is numeric, share 6 place to differ, if what the watch shows. Basic error reflected series of 2 basic error the place that tolerancepublic errand takes line of opposite Yu Ling. When tolerancepublic errand belt is located in 0 lines upper part, basic error is opposite to issue deviation EI(aperture) or Ei(countershaft) ; When tolerancepublic errand belt is located in 0 lines lower part, basic error to go up deviation ES(is opposite aperture) or Es(countershaft) . Beyond the tolerancepublic errand band that forms except basic error J, J and grade of certain tall public errand, basic error stands by 0 lines, namely that extreme deviation with lesser absolute value. The public errand that basic error JS, Js forms is taken, in each tolerancepublic errand grade, line of completely symmetrical Yu Ling, reason its are basic deviation is on deviation (+ IT/2) , yi Ke is next deviation (- IT/2) . From this, basic error of the axis is to H from A on deviation Es, it is next deviation to Zc from J; The basic error of aperture is next deviation EI to H from A, it is to ZC from J on deviation ES. The basic error of H and H is 0. Basic error numerical value expresses the origin of basic error the basic error numerical value of medium axis, aperture is the basic error in pressing a standard computational formula and numerical value repair those who make an appointment with regulation to get. The computational formula that the basic error of the computational axis of basic error of the axis presses place of A6 of the watch in appendix A to list is calculated. The computation of the basic error of the axis in the watch is formulary, be with base aperture makes those who cooperate to consider for the foundation, namely the basis cooperates property given. Basic error A comes the axis of H and fiducial aperture (H) comprises clearance fit, as it happens of its absolute value is equal to assorted the least space. H and H comprise the least space to be equal to a kind of clearance fit of 0, basic error is reason 0. Basic error J basically is used at transition fit to N. Among them the opening that J basically uses at matching with bearing photograph to close and axis, its numerical value is pure belong to experience data, without computational formula. Basic error P has been pressed to ZC be filled with cooperate to decide, basically be from the major attribute that assures to cooperate most peccadillo is filled with those who will consider, and be to press they and the most commonly used fiducial aperture H7 to close to consider for the foundation suitably mostly. List the basic error of the shaft that computational formula gets by the watch, it is commonly most that extreme deviation that stands by 0 lines, namely A reachs what H is an axis to go up deviation (Es) , next deviation that K is an axis to Zc (Ei) . Tell strictly except J and Js(both without basic error) outside, the numerical value of basic error of the axis and grade of chosen standard public errand have nothing to do. The computational new standard of the basic error of aperture stipulates the basic error of aperture and axis uses same calculation formula, because the basic error of this aperture can be gotten by basic error conversion of the axis. The basic error of the basic error of the aperture of code name of general and same basic error and axis is opposite Yu Ling line is complete semmetry, the absolute value of both basic error is so equal, and the symbol is contrary, namely: The type on EI=-es or ES=-ei applies to the basic error of all aperture, but following case is exceptional: Basic measure is more than 3 to 500mm, grade of standard public errand is less than or be equal to IT8, basic error is the Kong Hebiao of K, M, N to grade of accurate public errand is less than or be equal to IT7, basic error comes for P the aperture of ZC, in base aperture is made or basic shaft is made in, requirement aperture wants with taller the axis of one class is suitable (for example H7/p6 and P7/h6) , ask to have equal clearance or be filled with too. Below this kind of circumstance, the basic error of aperture should press type calculates: ES=ES(computation is worth) + in D type: D is basic measure paragraph inside given ITn of grade of some standard public errand and taller the poor value of the IT(n-1) of grade of standard public errand of one class. For example: Basic measure paragraph 18mm comes the P7 of 30mm, its D value is: The type of basic error computation that the basic error of D=ITn-IT(n-1)=IT7-IT6=21-13=8(µm) axis and aperture counts axis of the basis that be worth a watch and aperture, the standard gave out basic measure is expressed to the basic error numerical value of the axis of 3150mm and the basic error numerical value of aperture is expressed. After basic error of the axis is affirmatory, the basic error of the axis that another deviation of the axis can list by the place in standard watch and standard public errand (IT) gets: Come to basic error A H: Ei=es-IT of the deviation below the basic error that deviation Es= loses on comes to basic error K Zc: Next deviation Ei= after the basic error of aperture of Es=ei+IT of the deviation on basic error is affirmatory, the basic error of the opening that another deviation of aperture can list by the place in standard watch and standard public errand (IT) gets: Come to basic error A H: Next deviation EI= ES=EI+IT of the deviation on basic error comes to basic error K the K to be less than or be equal to IT8 mixes ZC(M8 is not applicable) : Of the grade of applied standard public errand of standard of EI=ES-IT3 of the deviation below the basic error that deviation ES= loses on choosing the principle that chooses grade of standard public errand is, below the premise of contented use requirement, choose inferior tolerancepublic errand grade as far as possible, so that resolve the contradiction between the use requirement of machine spare parts and finished cost well. Average gauge block chooses IT01, IT0 and IT1; Gauge chooses IT1 to IT7; Cooperate dimension to choose IT5 to IT13; Of particularly nice spare parts cooperate dimension to choose IT2 to IT5; Big production common difference (blame coordinate measure) choose IT12 to IT18; Raw material public errand chooses IT8 to be waited a moment to IT14. The applied standard of basic error set base aperture is made and basic shaft makes two kinds cooperate, recommend preferential choose base aperture is made cooperate. In base aperture is made in cooperating, basic error A of the axis is used at clearance fit to H; J is used at transition fit to had been mixed to Zc be filled with cooperate. Make in basic shaft in cooperating, the basic error A of aperture is used at clearance fit to H; J is used at transition fit to had been mixed to ZC be filled with cooperate. The basic error numerical value of the watch of numerical value of applied standard public errand of 3 numeric watches, axis is expressed and the watch of basic error numerical value of aperture is 3 the mainest numerical value in new GB watch. The extreme deviation of all aperture, axis (on, next deviation) all express computation according to these 3 and get. When using numeric list, should make clear and note the following problem: Grade of same public errand and same and basic measure paragraph aperture and axis, its standard public errand counts value homogeneous phase to be the same as. For example, φ the aperture of 50 and axis, the tolerancepublic errand numerical value of its IT7 all is 25µm. Standard public errand and basic error in principle each other are independent. It is commonly in section of same and basic measure, to different tolerancepublic errand grade, the numeric homogeneous phase of denotive basic error is the same as same letter. For example, in be more than 6mm to 10mm this one dimension paragraph in, no matter F6 or F8, its are basic deviation all is - 13µm. But the numerical value of a few basic error follows tolerancepublic errand social estate and change below: Basic error of the axis is J and K; The basic error of the aperture that be less than or is equal to IT8 is J to be P to the basic error of N and the aperture that be less than or are equal to IT7 to ZC. Illustrate is expressed by 3 numerical value below check basically dimension is 10mm, the axis of the grade of different public errand that basic error is P(P) , aperture is basic the corresponding circumstance of deviation: Because axial public errand takes P4, P6, P7, P8, P9,the basic error that wait and tolerancepublic errand grade have nothing to do, so next their deviation are + 0.

015. Manage together, the basic error that the public errand of aperture takes P8, P9 to wait also has nothing to do with tolerancepublic errand grade, so their on deviation is - 0.

015. But, when tolerancepublic errand grade is equal to or be less than IT7, the public errand of aperture takes P7, p6, the basic error that wait is worth P5, differ with respect to what follow tolerancepublic errand social estate and change, its are worth the corresponding numerical value to be more than IT7 (namely ES=-0.

015) and corresponding D are worth the sum. The D=0 of P7.

006, the D=0 of P6.

003, the D=0 of P5.

002, so: The basic error ES=-0 of P7.

015+0.

006=-0.

The basic error ES=-0 of 009(mm)P6.

015+0.

003=-0.

The basic error ES=-0 of 012(mm)P5.

015+0.

002=-0.

013(mm) notices numerical value expresses specific suitable scope. CNC Milling