鑄鐵平臺精度及氣孔砂眼的基本知識

時間：2015/12/26 13:37:37 瀏覽量：366

鑄鐵平板基本知識

1、范圍

本標(biāo)準(zhǔn)規(guī)定了精度等級為000級、00級、0級、1級、2級、3級。

鑄鐵平板的型式與尺寸，技術(shù)要求，檢驗方法，標(biāo)志與包裝等。

本標(biāo)準(zhǔn)適用于工作面為160m×100mm～4000mm×2500mm（長度×寬度）的鑄鐵平板（以下簡稱平板）。

2、引用標(biāo)準(zhǔn)

下列標(biāo)準(zhǔn)所包含的條文，通過在本標(biāo)準(zhǔn)中引用而構(gòu)成為本標(biāo)準(zhǔn)的條文，本標(biāo)準(zhǔn)出版時，所示版本均為有效。所有標(biāo)準(zhǔn)都會被修訂，使用本標(biāo)準(zhǔn)的各方應(yīng)探討使用下列標(biāo)準(zhǔn)最新版本的可能性。GBT1184--1996形狀和位置公差，未注公差的規(guī)定。

3、定義

本標(biāo)準(zhǔn)采用下列定義：

3.1 平板：用于工件檢測或劃線的平面基準(zhǔn)器具，又稱為平臺。

3.2 主支點(diǎn)：平板在加工，檢定和使用中，與安裝基面或?qū)Ｓ弥Ъ芙佑|時，用作主要支承的部分。此時的支承為系靜定狀態(tài)。

3.3 輔助支點(diǎn)：平板在使用時，為了防止因負(fù)載重心的偏移而發(fā)生傾覆或因負(fù)載過大而產(chǎn)生有害的變形所增設(shè)的支點(diǎn)。輔助支點(diǎn)上的支反力應(yīng)小于主支點(diǎn)上的支反力。

4、型式與尺寸

筋板式平板的輔助支點(diǎn)是為了防止使用的平板因重心偏移而發(fā)生傾覆所設(shè)置的。對負(fù)載過大而產(chǎn)生有害變形的輔助支點(diǎn)由設(shè)計者自行設(shè)計，但數(shù)據(jù)應(yīng)控制在最少限度。輔助支承面與主支承面不應(yīng)在同一平面上，以便于調(diào)整輔助支點(diǎn)的反力。

5、技術(shù)要求

5.1 平板工作面不得有嚴(yán)重影響外觀和使用性能有砂孔、氣孔、裂紋、夾渣、縮松、劃痕、碰傷、銹點(diǎn)等缺陷。

5.2 平板的鑄造表面應(yīng)清除型砂且平整，涂漆牢固。

5.3 精度等級為0級～3級的平板工作面上，直徑小于15mm的砂孔允許用相同的材料堵塞，其硬度應(yīng)小于同圍材料的硬度。工作面堵塞的砂孔應(yīng)不多于4個。且砂孔之間的距離應(yīng)不小于80mm。

5.4 平板應(yīng)采用優(yōu)質(zhì)細(xì)密的灰口鑄鐵或合金鑄鐵等材料制造，其工作面硬度應(yīng)為170～220HB。

5.5 平板工作面通常應(yīng)用采用刮削加工藝。對采用刮削加工期的3級平板工作面，其表面粗糙度Ra的最大允許值為5чm。

5.6 平板工作面采用刮削工藝應(yīng)進(jìn)行涂色對研檢驗。按25mm×25mm中的接觸點(diǎn)數(shù)之差應(yīng)不大于5點(diǎn)。若有爭議，按接觸點(diǎn)面積的比率為評定依據(jù)。

6、檢驗方法 

6.1 接觸點(diǎn)面積的比率

將被檢平板工斜面上涂上顯示劑，在不低于其精度等級的平板上研合，在被檢平板上顯示出明顯的接觸點(diǎn)，然后用一個50mm×50mm范圍內(nèi)刻劃有2.5mm×2.5mm的400個小方格的透明薄板(如有機(jī)玻璃板)，置于被檢平板工作面的任意位置上，依次觀察每個方格內(nèi)包含接觸點(diǎn)所占面積的比例(以1/10為單位)。求上述比例數(shù)之和，除以4即為所檢測部位的接觸點(diǎn)面積的比率，為取得典型的數(shù)值。應(yīng)在另一位置上測出接觸點(diǎn)面積的比率，求出兩次結(jié)果的平均值。

6.2 平面波動量

將平面波動儀放在平板工作面上，沿任意一直線方向移動平面波動儀。移動距離為平板對角線長度的一半且不應(yīng)小于200mm。取平面波動儀的指示表(分度值為0.001mm)上最在值與最小值之差，即為被檢平板工作面的平面波動量。

6.3 撓度：將檢測裝置放在被檢平板工作面上，在不加載荷時，將扭簧比較儀測頭與工作面相接觸(為使測量準(zhǔn)確,測頭與工作面之間可放一塊薄量塊)且記下讀數(shù)。然后根據(jù)表5規(guī)定的額定載荷施加力且記下讀數(shù)，兩次讀數(shù)之差，即為被檢平板工作面在額定載荷下的撓度值。

Basic knowledge of cast iron plate

1. Scope

This standard stipulates that the accuracy level is 000, 00, 0, 1, 2 and 3.

Type and size of cast iron plate, technical requirements, inspection methods, marking and packaging, etc.

This standard is applicable to cast iron slabs (hereinafter referred to as slabs) with a working face of 160m *100mm~4000mm *2500mm (length *width).

2. Citation criteria

Provisions contained in the following standards constitute provisions of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GBT1184-1996 Shape and position tolerances, no tolerances specified.

3. Definition

This standard adopts the following definitions:

3.1 Flat Plate: A flat benchmark for workpiece inspection or marking, also known as a platform.

3.2 Main fulcrum: The plate is used as the main supporting part when it is in contact with the installation base or special support in processing, verification and use. At this time, the support is statically determinate.

3.3 Auxiliary fulcrum: A fulcrum added to a plate to prevent overturning due to the deviation of the center of gravity of the load or harmful deformation due to excessive load. The supporting force at the auxiliary fulcrum should be less than that at the main fulcrum.

4. Types and Dimensions

The auxiliary fulcrum of ribbed plate is set up to prevent the overturning of the plate due to the deviation of the center of gravity. The auxiliary fulcrum for harmful deformation caused by excessive load is designed by the designer himself, but the data should be controlled to a minimum. The auxiliary support surface and the main support surface should not be on the same plane, so as to adjust the reaction of the auxiliary support.

5. Technical Requirements

5.1 No serious defects affecting the appearance and performance of flat face, such as sand holes, air holes, cracks, slag inclusion, shrinkage, scratches, bruises and rust spots, shall be allowed.

5.2 The casting surface of flat plate should be clean and smooth with solid paint.

5.3 In flat working face with accuracy grade 0-3, sand holes less than 15 mm in diameter are allowed to be blocked by the same material, and their hardness should be less than that of the surrounding material. There should be no more than four sand holes blocked in the working face. And the distance between the sand holes should not be less than 80 mm.

5.4 Flat plate should be made of fine gray cast iron or alloy cast iron with hardness of 170-220HB.

5.5 Scraping technology is usually used in flat face. The maximum allowable value of surface roughness Ra is 5 m for the three-stage plate working face during the scraping period.

5.6 Scraping technology should be used in flat face to carry out colouring and grinding inspection. The difference between the contact points in 25mm x 25mm should be no more than 5 points. In case of disputes, the ratio of contact area shall be used as the basis for evaluation.

6. Inspection methods

6.1 Ratio of contact area

The inspected slab is coated with the displaying agent and lapped on the slab of no less than its accuracy grade. The obvious contact points are displayed on the inspected slab. Then 400 transparent sheets (such as plexiglass) with 2.5 mm x 2.5 mm are inscribed in a range of 50 mm x 50 mm and placed at any position on the working face of the inspected slab. In turn, the proportion of the area containing contact points in each grid (in 1/10 units) was observed. The sum of the above proportions is divided by 4, which is the ratio of the contact area of the detected part, so as to obtain the typical value. The ratio of contact area should be measured at another location, and the average value of the two results should be calculated.

6.2 Plane Wave Volume

Place the planar wave meter on the working surface of the flat plate and move the planar wave meter along any straight line direction. The moving distance should be half of the diagonal length of the plate and not less than 200 mm. The difference between the maximum value and the minimum value on the indicator table of the plane wave meter (the indexing value is 0.001 mm) is taken as the plane wave quantity of the inspected flat face.

6.3 Deflection: Place the detection device on the working face of the tested flat plate. When the load is not loaded, contact the probe of the torsion spring comparator with the working face (in order to make the measurement accurate, a thin measuring block can be placed between the probe and the working face) and record the reading. Then, according to the rated load specified in Table 5, the force is applied and the reading is recorded. The difference between the two readings is the deflection value of the Workface under the rated load.

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