Rubber sheet rolling and inspection standards: Which measuring instruments are suitable for monitoring quality on the production line

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Rubber sheets are made by calendering and bonding compounded rubber or by extrusion, and then vulcanized using a flat vulcanizing machine or through continuous vulcanization in a drum vulcanizer. It is widely used in industrial and mining enterprises, transportation sectors, as well as in building floors and other applications. Used as sealing gaskets, rubber pads, door and window seals, as well as for laying workbenches and floors. Rolling process: Plasticization of insulating rubber sheets ； Mixing ； Rolling and extrusion, molding and vulcanization ； Inspected before leaving the factory. Rubber sheets can only leave the factory after being inspected, and the inspection carried out by staff is a crucial step. With the development and advancement of measuring instruments, some quality checks can now be performed through online testing, which also allows for the generation of inspection records; these records contain more data than those obtained through manual inspection, and they are more accurate as well. Testing standard for rubber sheets: GB/T 528 – Determination of tensile properties of vulcanized rubber sheets and thermoplastic rubber sheets. GB/T 531 Test method for Shore A hardness of rubber sheets. GB/T 1682 Test method for brittle temperature of vulcanized rubber sheets. GB/T 1690 Test method for resistance of vulcanized rubber sheets to liquids. GB/T 3512 Test method for hot air aging of rubber sheets. GB/T 5575 Unvulcanized rubber sheets for lining chemical equipment. GB/T 6031 Test method for international hardness of vulcanized rubber sheets (30–85 IRHD) – Routine test. GB/T 7759 Determination of permanent set under constant deformation at normal and high temperatures for vulcanized rubber sheets. GB/T 7762 Test for ozone aging resistance of vulcanized rubber sheets – Static tensile test method. GB 11176 Electric insulating rubber sheets. HG/T 2180 Natural vulcanized rubber sheets for lining phosphate storage tanks. Test data: 1. Appearance 1) The depth and height of the scars do not exceed the tolerance for the thickness of the adhesive sheet. 2) Per square meter, there shall be no more than 5 bubbles with an area of less than 1 cm, and the distance between any two bubbles shall be at least 40 mm. 3) The depth and length of impurities shall not exceed 1/6 of the thickness of the rubber sheet. 4) The uneven edges or sea-like areas shall have a width of no more than 10 mm, and a length of no more than 1/10 of the total length of the adhesive sheet. 5) No cracks. 2. Hardness (Shore A): 55–70 3. Tensile strength and elongation at break: 1) Tensile strength (Mpa) ≥ 5.0 2) Elongation at break ≥ 250% 4. Permanent set at 150% strain ≤ 25% 5. Heat air aging (70°C * 72 hours): Reduction in tensile strength ≤ 30% 6. Water absorption ≤ 1.5% 7. Electrical insulation performance tests: 1) Withstand voltage test: 25 KV (r.m.s.), for 1 minute; no breakdown should occur. 2) Breakdown voltage test ≥ 35 KV (RMS). Some automated inspection equipment used for rubber sheets: 1. Width measurement – An online width detector, a type of device capable of performing measurements regardless of the sheet width; it can be customized to cover any desired measurement range, and is used for measuring the width of sheets online. (PS: For circular rubber products such as rubber hoses and rubber rods, the outer diameter can be measured; using dual-axis detection, information on ellipticity can also be obtained.) 2. Thickness information: Laser thickness gauges are used for online measurement of thickness. By using different arrangements of laser probes, multiple measurements can be taken, which is very effective for measuring the thickness of wide rubber sheets. 3. Length measurement is carried out using machine vision detection; depending on the length of the rubber sheet, multiple sets of industrial cameras are arranged to jointly determine the width. 4. Detection of rebound capacity: Also based on the principle of optical measurement, a pressing mechanism is used to compress the rubber sheet; after a certain period of time, as it returns to its natural state, the data is measured to calculate the rebound capacity, and a rebound capacity–time curve is drawn. 5. Surface defects: Profile measuring instruments can detect certain information regarding surface defects, such as cracks. By using a range of automated measurement devices for rubber sheets, the workload on staff is reduced, and more accurate as well as greater quantities of inspection data can be obtained. Quality inspection is a very important process, and the task of automated measurement instruments is to carry out this quality check in a more efficient manner, saving time and effort.