Pressboard

About: Pressboard is a research topic. Over the lifetime, 1123 publications have been published within this topic receiving 9089 citations.

Be used for paper products post forming machine

Abstract: The utility model discloses a be used for paper products post forming machine, its characterized in that: including the base, set up the supporting legs bottom the base, set up mould mounting plate onthe base, at the pressing mechanism of mould mounting plate top setting by control circuit control, set up on the base and control the panel. The utility model discloses simple structure, cost of manufacture are hanged down, through the cooperation of pneumatic cylinder with the pressboard, adopt automatic mode of suppressing, have effectively reduced workman's work load, improvement pressing efficient, and under the suppression of pressboard, can evenly suppress the paper article, and improve paper article shaping rate, have characteristics such as simple operation, pressing efficient height.

Buffering structure of single corrugated board

Abstract: The invention discloses a buffering structure of a single corrugated board. The buffering structure comprises a single corrugated board body with a rectangular shape; crease is arranged on the single corrugated board to divide the corrugated board into a bottom pressboard and side pressboards at two sides; the crease of the side boards at two sides is wrapped towards the bottom pressboard, thereby forming two phases of parallel hollow rectangular columns with sections of different height; the matching between a clamping tongue of the side pressboard and a first clamping hole of the bottom board, between a second clamping hole of a flank pressboard and the clamping wall of the side pressboard and between a first clamping mouth of the flank pressboard and a second clamping mouth of the sidepressboard is utilized to fix two hollow rectangular columns on the bottom pressboard; and the flank pressboard is utilized to support the inner wall of two hollow rectangular columns. The buffering structure of the single corrugated board protects the environment, saves the cost and has the advantages of simple operation and convenient and firm molding.

Differential time-domain spectroscopy technique based on polarization and depolarization current and their applications in oil-paper insulation estimation

Abstract: To quantificationally apply the results of polarization and depolarization currents (PDC) measurement for condition evaluation of oil-paper insulation in power transformer, the differential time-domain spectroscopy (DTDS) theory and the extraction technique of sensitive characteristic parameters are introduced. A set of oil-immersed paper samples are thermally acceleratedly aged at high temperature (∼150 °C) in laboratory based on the developed platform for oil-paper insulation thermal aging and dielectric response test. Under different temperatures (30, 40, 50, 60, 70 °C) and different aging degrees, PDC tests are performed on one of the samples by real-time tracking during the whole aging period. And at each aging stage, the aided tests, such as moisture content dissolved in oil and degree of polymerization (DP) of cellulose paper are measured. The test and analysis results show that aging condition has evident effect on DTDS curves. With sample aging, the DTDS curve shifts upwards. The extracted characteristic parameter, polarization response time t1 of the interfacial polarization between oil and pressboard, is regular and sensitive to aging condition changing. The influence mechanisms of aging on the time domain dielectric properties are analyzed. The empirical formula representing the relation among temperature, aging condition, and dielectric response in time domain is developed by means of 3-D surface fitting technique, to preliminarily investigate the application method of time-domain dielectric test.

Electrical conductivity of oil and oil-impregnated pressboard dependent on aging byproducts

Abstract: The estimation of material parameters is an essential step during the design of high voltage direct current (HVDC) insulation systems. The key role of insulation coordination in power transformers is to provide the required insulation components among different voltage classes to prevent dielectric breakdown. The design of a feasible insulation for transformers requires understanding of electrical field distributions. The DC field stresses are determined by means of insulating material conductivity which is normally a combination of dielectric liquid, paper and pressboard. One of the parameters which has an influence on the electrical conductivity is the aging of solid and liquid insulations. During converter transformer operation time, there is a normal degradation of all insulation materials. Aging byproducts like various acids increases the electrical conductivity of the system. This can lead to a variation of the field distribution over the operation time of the converter transformer. In this contribution, the influence of different carboxylic acids on electrical conductivity of oil and impregnated pressboard is investigated. The results compare the effects of adding different amounts of hydrochloric acid to mineral oil and natural ester liquid during electrical conductivity measurement. The conclusion illustrates different behavior of electrical conductivity comparing short and long-chain acids content of specimens.

Polarization and Depolarization Current Characteristics of Natural Ester Impregnated Pressboards with Different Periods of Impregnation

Abstract: This paper represents the polarization and depolarization current (PDC) characteristics of natural ester impregnated pressboards with different impregnation period. The pressboard specimen were prepared as a rectangular shape (the length and the width are 120 mm as well) and thickness dimension of the pressboard in the experiment was approximately 1.6 mm. The pressboards were dried up in the vacuum oven with temperature at 80°C for 12 hours under 200 mbar pressure. In addition, these pressboards were divided into 3 groups according to the impregnation periods. The 1st group, the pressboard was non-impregnated with natural ester. The 2nd and 3rd group, the pressboards were impregnated at 60°C for 8 and 16 hours, respectively, under 200 mbar pressure-controlled condition. The plane-plane electrodes inserted with the specified number of the pressboard specimens were prepared. These electrodes were installed in the test cell filled with the natural ester. A 24 kV AC Voltage was applied to the test cell for 3 months. At the end of the first month, half of the pressboard samples was token from the test cells. Then, the PDC characteristics of these natural ester impregnated pressboards were investigated. At the end of the third month, another half of the pressboard samples was token from the test cells to perform PDC measurement also. It was found that the PDC values of the pressboards with longer period impregnation process were lower than these of the pressboards with longer period impregnation process. Besides, the PDC values of the pressboards experienced with longer electric field stress period (3 months) were higher than these of the pressboards experienced with shorter electric field stress period (1 month).