CN112062513A - Jig and manufacturing method - Google Patents

Abstract

The invention provides a jig and a manufacturing method, and the jig is characterized in that: the jig is made of cement materials. Because the cement material is high temperature resistant, the high-strength part is easy to manufacture, the high-strength part has the characteristic of being less prone to deformation, and the rigidity of the whole jig is increased, so that the jig is less prone to bending deformation and longer in service life than the existing jig.

Description

Jig and manufacturing method

Technical Field

The invention relates to a jig and a manufacturing method.

Background

At present, a known jig used in the electronic industry uses a plastic material, such as bakelite, synthetic stone, glass fiber board, etc., and the plastic material is easier to bend and deform at high temperature due to its lower strength.

Disclosure of Invention

The invention aims to provide a jig which is more resistant to high temperature, not easy to bend and deform and longer in service life than the existing jig.

The purpose of the invention is realized as follows: a jig is characterized in that: the jig is made of cement materials.

The jig also comprises fine quartz sand.

The jig also comprises silica fume.

The jig also comprises fine sand.

The jig also comprises fibers.

The jig also comprises a high-efficiency water reducing agent.

The jig also comprises conductive carbon black.

A method of manufacturing a jig, comprising: adding water to cement and stirring the cement into a raw material; adding the raw materials into a mould to be processed into the jig.

The mould comprises a lower mould, and the raw materials are added into the lower mould to be processed into the jig.

The mould comprises an upper mould and a lower mould, the raw material is placed on the lower mould, and the upper mould presses and forms the raw material into the jig through the pressing process.

The inventive jig is characterized in that; the jig is made of cement materials. The cement material is high temperature resistant, and parts with high strength and high hardness are easy to manufacture, so that the rigidity of the whole jig is increased, the jig is less prone to bending and deformation and has a longer service life than the existing jig.

Drawings

The invention will now be further described with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of a first embodiment of the inventive jig;

FIG. 2 is a cross-sectional view taken along line C-C of the jig shown in FIG. 1;

FIG. 3 is a schematic cross-sectional view of a second embodiment of the inventive fixture;

fig. 4 is a D-D sectional view of the jig shown in fig. 3.

Fig. 5 is a schematic cross-sectional view of a third embodiment.

Fig. 6 is a schematic view of a mold and a jig in the first manufacturing method.

Fig. 7 is a schematic view of a mold and a jig in a second manufacturing method.

Detailed Description

Example 1

Referring to fig. 1 to 2, the jig of the invention comprises a cement main body (1) and a high-strength part (2) wrapped in the cement main body (1), wherein the high-strength part (2) is a steel frame or a titanium alloy frame.

Example 2

Referring to fig. 3 to 4, the jig comprises a cement main body (1) and a high-strength part (2) wrapped in the cement main body (1), wherein the high-strength part (2) is a steel rod or other non-metallic fiber parts.

Example 3

Referring to fig. 5, the jig of the invention comprises a cement main body (1) and a high-strength part (2) wrapped in the cement main body (1), wherein the high-strength part (2) is a steel rod or other non-metallic fiber parts. The angle iron (4) inserted into the wave-soldering claw is assembled on the jig, the silicon rubber strip (3) for preventing the bottom of the jig from colliding is fixed below the jig and can be fixedly connected through fastening, and the tin blocking part can be made of cement.

Referring to fig. 6, the mold in the first manufacturing method includes an upper mold (1) and a lower mold (4), the jig (2) includes a slurry inlet (3), after the upper mold (1) and the lower mold (4) are tightly fitted, the prepared cement slurry is poured into the cavity of the mold through the slurry inlet (3), and the purpose of internal uniformity of the cement slurry is achieved through the vibrating mold. And demolding after the cement is hardened for 24 hours, and placing the large plane surface of the jig on the plane for maintenance. In some cases, the jig can be manufactured by only using the lower die without the upper die.

Referring to fig. 7, the mold in the second manufacturing method includes an upper mold (1) and a lower mold (4), the raw material with a certain weight is weighed by the dry stirred ingredients and placed on the lower mold (4), then the excess moisture in the raw material is extruded out by the upper mold (1) through the pressing process, the raw material is pressed to form a jig (2), the jig (2) can be demoulded, and the large plane surface of the jig is placed on the plane for maintenance. This method is similar to the method for making cement encaustic tiles.

The design theory of ultra-high performance concrete is maximum packing density theory (dense particulate packing), and particles with different particle diameters of the composition materials form the closest packing in the optimal proportion, namely, gaps formed by the stacking of millimeter-sized particles (aggregates) are filled with micron-sized particles (cement, fly ash and mineral powder), and gaps formed by the stacking of micron-sized particles are filled with submicron-sized particles (silica fume). Andressen established a mathematical model of the maximum packing density theory as early as 1931. However, until the end of the seventies of the last century, the first generation of ultra-high performance concrete formulated using this model design was born in the university of Beton laboratory, Denmark, as CRC (Compact Reinforced Composite), based on the dramatic improvement in superplasticizer technology and product performance. CRC achieves basically the same mechanical property as the current UHPC, the maximum compression strength exceeds 400MPa, sintered bauxite is used as aggregate, and steel fiber is used to improve the toughness of the material, so the composite material is called. Due to the limitation of the performance of the high-efficiency water reducer at that time, CRC or early UHPC is viscous, and the vibration is difficult to compact, so that the cast-in-place application is inconvenient. In the nineties of the last century, cooperative research projects are carried out in Europe, related researches are also widely carried out all over the world, and the material obtains a new name of Reactive Powder Concrete (RPC). The name of the ultra-high performance concrete UHPC is formed in the century, because compared with the early CRC or RPC, along with the perfection of the design theory, the appearance of the ultra-high efficiency water reducing agent (polycarboxylic acid series) and the improvement of the preparation technology, the material has the construction performance of the common concrete, even can realize self-compaction, can be cured at normal temperature and has wide application conditions. The different aspects of UHPC from ordinary concrete or high-performance concrete include: without using coarse aggregate, silica fume and fiber (steel fiber or composite organic fiber) are used, the cement consumption is large, and the water-cement ratio is low. The ultra-high performance concrete UHPC (steel fiber) comprises, by weight, 27.0-38.0% of cement, 8.5-9.5% of silica fume, 0.0-8.0% of ground quartz sand, 39.0-41.0% of fine sand, 5.5-8.0% of metal fiber, 0.5-1.0% of high-efficiency water reducing agent and 5.5-8.0% of water. The tensile property of UHPC is close to that of steel! The UHPC has been said to have a maximum compressive strength of up to 810MPa (i.e., RPC800, using short steel fibers and steel aggregate, press forming test pieces at 50MPa pressure, and curing at high temperature and pressure of 250-400 ℃). The metal fibers may be replaced with non-metallic fibers.

The reinforcement material of reinforced concrete structure is characterized by that the Fibre Reinforcement (FRP) bonded by resin is used as non-metal reinforcement of woollen concrete and prestressed concrete structure, and the general fibre reinforcement has the carbon fibre reinforcement (GFRP), Glass Fibre Reinforcement (GFRP) and Aramid Fibre Reinforcement (AFRP) bonded by resin. The fiber rib has the outstanding advantages of corrosion resistance, high strength, good fatigue resistance, large elastic deformation capacity, high resistance and low magnetic conductivity, and has the disadvantages of poor fracture strain performance, brittleness, large creep (relaxation) value and large thermal expansion coefficient. Fibers and products made of fibers (cloth, strips or plates) can be used for the jig.

The high-strength concrete prepared by the method is characterized by adopting Portland cement, ordinary Portland cement or pozzolanic Portland cement with high C3S content and fineness (the surface area is 3500-4000 cm/s), wherein the grade of the cement is 0.9-1.5 times of the strength grade of the corresponding concrete, and the dosage of the cement is required to be controlled at 500-700 kg/m3 Within the range. The prepared high-strength concrete must adopt the cube macadam with rough surface and no dust with the strength index larger than 2.0, and preferably adopts dense aggregates of granite, diabase, marble and the like, the grain diameter must be solid and have edges and corners, and the grain diameter must be between 10 mm and 35 mm. Preparing high-strength concrete, wherein clean sand with fineness modulus of 2.5-3.0 is required, and the water content is reduced as far as possible. The prepared high-strength concrete must adopt clean water with ph more than 4, and the water-cement ratio must be between 0.28 and 0.35. The high-strength concrete is prepared by adopting high-efficiency water reducing agents such as NN0, MF and the like.

Preparing high-strength concrete: selecting raw materials such as cement, aggregate and the like; secondly, a high-efficiency water reducing agent is required to be added to reduce the water consumption and the water-cement ratio; high-quality mineral admixture is blended to improve the microstructure of the set cement and the interfacial area and improve the compactness and the cementing strength; fourthly, carefully selecting the mixture ratio, and determining the reasonable sand rate and the water cement ratio so as to reduce the consumption of cement and improve the strength of concrete; and fifthly, strictly controlling construction quality and well performing early maintenance. Effective preparation of high-strength concrete is possible only by comprehensively adopting the technical measures.

1. Selection of cement

The mineral composition and grade of the cement have direct influence on the strength of the concrete. It is known that the mineral constituent of portland cement consists mainly of c3s.c2s.c3a.c4 af. The cement with low C3A content is preferably used for preparing the high-strength concrete, the hydration heat of the cement is lower, and the later strength development is better. The high-strength concrete is generally common Portland cement of a high-grade arch, the dosage of the cement is not more than 550kg/m3 according to the specification, and the total amount of the cement and mineral admixture is not more than 600kg/m 3. Tests have shown that, when the amount of cement used exceeds 500kg/m3, the effect of the cement amount on the increase in concrete strength is not significant and the coefficient of utilization of cement decreases. At this time, increasing the amount of cement not only increases the cost, but also has an adverse effect. The optimal cement dosage varies with the dispersion water-reducing effect of the admixture. The strength of concrete is greatly influenced by cement marks, when the strength grade does not exceed C60, ordinary No. 425 cement can be used, and concrete with the strength grade higher than C60 should use cement with the strength grade of 525 or higher. The high-strength concrete can be prepared by adopting cement with a lower mark number, and the detection of the mark number of the cement adopts thinner standard sand and larger water-cement ratio, and the concrete is added with the high-efficiency water reducing agent, so that the cement is fully diffused and hydrated.

2. Selection of coarse and fine aggregate

The high-strength concrete is preferably selected from broken stones or cobbles with the grain size of more than 5 mm. The rock variety requires granite, feldspar, basalt and the like, and gneiss, quartzite, limestone and the like are the best. The strength of the rock is expressed by ultimate compression strength and crushing value (the pebbles are only measured by crushing value), the ratio of the compression strength of the rock to the strength of the concrete is not less than 1.5, and the index of the crushing value is below 10-15%. Other physical properties of the aggregate are also influential to the concrete. The concrete has low water absorption, and few pores and defects, so the concrete has high strength, strong frost resistance and small shrinkage; the aggregate should also have a thermal expansion coefficient and elastic modulus similar to those of set cement, otherwise micro cracks are easily generated, the penetration of concrete is increased, and the durability is reduced; if the coarse aggregate is too hard, the volume change is easy to cause when the concrete is subjected to temperature and humidity change, and the rising crack damage is easy to form when the stress at the cement stone-aggregate interface is larger. Because the cement stone in the high-strength concrete has high strength, the cohesive force (cementing strength) between the cement stone and the aggregate is also strong. In the fracture section of concrete, the rate of damage to the coarse aggregate is large, so the strength of the coarse aggregate often becomes an important constraint factor for high-strength concrete. In addition, the possible microcrack weak areas in the parent rock can be damaged along cracks during crushing, so that small crushed stones formed after crushing can often obtain higher strength than a large sample of the parent rock. This is one of the reasons why the high-strength concrete should use the aggregate having a small particle size. Macroscopically, the concrete is composed of a coarse and fine aggregate and a cement-stone two-phase system. Microscopically, the cement stone in the cement stone-aggregate interface area has larger difference with a cement stone matrix in a system, the interface area forms higher water cement ratio and more pores, is generally weaker than other two thicknesses of concrete, and is the weakest part in the system. If the bond strength at the interfacial region is low, it will break down along the interfacial region. Many studies have indicated that high strength concrete should use coarse aggregates of small particle size. Because the surface area of the small-particle-size coarse aggregate is relatively increased, the stress on the unit surface area of the cement-aggregate interface area is greatly reduced, and the requirement of the interface area on the cementing strength is reduced, so that the interface area with higher cementing strength can be obtained, and the external load with higher strength can be borne. On the contrary, the coarse aggregate has a large particle size, a small surface area to be bonded with the set cement, and a weak interface region is easily formed to weaken the strength of the concrete. In common medium and low-grade concrete, the requirement of the bond strength of the interface area is not very high, and the requirement is easily met, if the condition permits, the aggregate with larger grain diameter is required to be used as much as possible so as to save the cement. However, high-strength concrete with a higher strength grade is different, and if the surface area is not increased by adopting coarse aggregate with small grain size, the high-strength concrete cannot be prepared. The maximum particle size of the aggregate is preferably 10-15 mm in foreign countries, and generally not more than 20-25 mm is preferred for saving cement. The effect of fine aggregate on high strength concrete is small compared to coarse aggregate, but it is not negligible. The medium grit with the fineness modulus of 2.6-3.2 is selected to be clean, and the grit with the fineness modulus of 3.0 is the best. Of these, the amount larger than 5mm and smaller than 0.315mm is preferably small. Because the fine aggregate has larger surface area than the coarse aggregate, the ratio (sand rate) between the coarse aggregate and the fine aggregate has great influence on the cement using amount and the concrete strength, the best sand rate can obtain the best strength, and the workability of the high-strength concrete is not influenced by properly reducing the sand rate due to the large cement using amount.

3. High-quality mineral admixture for blending

The mineral admixture of fly ash, levigated slag, silica powder, zeolite powder and the like can improve the workability of concrete and increase the cohesiveness of the admixture. Due to the change of cohesiveness, the water migration channel is cut off, and bleeding and segregation can be reduced. Water and high precipitation are the main causes of defects in the microstructure of concrete, especially the structure at the interface region of cement-aggregate. Therefore, the incorporation of mineral admixtures into the high-strength concrete is not only aimed at saving cement, but also at improving the micro-structure and performance of the concrete. The slag powder, the fly ash and the silica fume belong to volcanic ash materials, and can be slowly hydrated in the presence of water and lime to generate a gelled substance for increasing the strength and fill pores in concrete. When fly ash is not blended, not only a high cement ratio region is formed in the aggregate-cement interface region, but also ca (oh) is generated. The crystals are large and arranged in an orientation mode, and are porous and plate-shaped weak structures. After the fly ash is doped, Ca (OH) can be reduced. The amount of deposition in the interface region; if a finer silica powder or zeolite powder is incorporated, Ca (OH) is more involved. And (4) reacting. The generated C-S-H gel is in an amorphous and compact structure, so that the microstructure of a two-phase interface area is obviously improved, and the strength, the impermeability and the durability of concrete can be improved. The silica fume contains 90% or more of Si 0. The mixing amount is 5-10%. The concrete doped with the silica fume has good combination easiness and stability. Zeolite is porous crystalline mineral composed of silicon-oxygen tetrahedron, and after zeolite powder is doped into concrete, the hydration can be uniformly and fully reacted, so that the compactness and strength are improved. If mineral admixture with low activity is mixed, the mineral admixture is uniformly distributed in cement paste to form a large amount of hydrate deposition cores, and the cement paste becomes uniformly distributed microporous amorphous hydrate, so that the nonuniform structure of a crystal block is reduced, and the cement paste is also very favorable for strength and impermeability.

4. High-efficiency water reducing agent for blending

Because high-strength concrete must adopt high cement dosage and low cement-to-cement ratio, the concrete inevitably has high viscosity and poor rheological property. After the high-efficiency water reducing agent is doped, the high-efficiency water reducing agent has strong dispersing and lubricating effects on cement, can greatly reduce the water consumption, and makes it possible to reduce the water-cement ratio to the maximum extent. Therefore, the high-efficiency water reducing agent naturally becomes one of the essential components of the high-strength concrete. The water cement ratio is a main factor for controlling the strength of the set cement and the concrete, and tests show that when the water cement ratio is lower than 0.35, the properties of an interface area are obviously improved, and the compactness and the strength are obviously increased. The bound water required for hydrating portland cement is about 28% in theoretical value, and the directly measured chemically bound water is about 25% in theoretical value, and when the actual cement-to-cement ratio is lower than the theoretical value, the hydration of cement is incomplete, and the set cement cannot reach enough compactness. Combining the conditions of mixing, pouring and curing, under the condition of adding the high-efficiency water reducing agent, the water-cement ratio of the high-strength concrete is generally not more than 0.35, and when the strength is more than 80MPa, the water-cement ratio is not more than 0.25-0.30.

5. Strengthen construction control and early maintenance

According to the characteristics of high cement dosage and hydration blocks of the high-strength concrete, the following measures are adopted in the construction:

(1) the materials are fed and mixed step by step. Mixing cement, admixture, sand and water for about 40s, adding stones and a water reducing agent, stirring for 1min, and taking out. Thus, the function of the water reducing agent can be fully exerted, good pouring performance is kept, and the strength can be improved. Under hot conditions, the temperature of the various materials is kept as low as possible. (2) And (5) transporting by adopting a stirring transport vehicle. And (4) completing the stirring till the pouring is finished according to the temperature limit. (3) High-frequency vibration is adopted. Even with fluid concrete, it should be vibrated to improve compaction. (4) And strengthening early maintenance. Because the hydration is rapid, the watering maintenance is needed in the early stage, so that the hydration is ensured not to lack water, and the strength development is not influenced. (5) The slump is reduced as much as possible. Under the condition of condition permission, water is added as little as possible, and the small slump constant is adopted and still remains as an important measure for improving the strength.

The procedure of processing the cement board into the jig can adopt a numerical control milling machine for processing.

(1) Stirring concrete: according to different construction requirements and conditions, the concrete can be intensively stirred on a construction site or a stirring station. The concrete mixture with better fluidity can be used by a free fall mixer; concrete with low fluidity or dry and hard property is preferably stirred by a forced mixer. The materials are prepared according to the mixing proportion requirement before stirring, and the weighing error is controlled. The feeding sequence and the stirring time have influence on the quality of the concrete and need to be mastered strictly so that the materials of all the components are uniformly mixed. (2) Conveying and pouring concrete: the concrete mixture may be transported to the construction site by a hopper, belt conveyor or truck mixer. The pouring mode can be manual or by means of machinery. The concrete pump is adopted to convey and pour concrete mixture, the efficiency is high, and the mixture can reach hundreds of cubic meters per hour. In both concrete cast-in-place engineering and prefabricated components, the compactness of the concrete after pouring must be ensured. The method mainly adopts vibration tamping, and also adopts centrifugation, extrusion, vacuum operation and the like. The fluid concrete mixed with some high-efficiency water reducing agent can not be vibrated. (3) Curing the concrete: the purpose of curing is to create proper temperature and humidity conditions to ensure or accelerate the normal hardening of concrete. Different curing methods have different effects on the concrete properties. The common curing methods include natural curing, steam curing, wet-heat curing, autoclaved curing, electric heating curing, infrared curing, solar curing and the like. The time of curing is called curing period. For the sake of comparison, it is specified that test pieces for measuring concrete properties must be cured under standard conditions. The standard curing conditions adopted by China are as follows: the temperature is 20 +/-3 ℃: the humidity is not lower than 90%.

The jig also comprises conductive carbon black, the conductive carbon black is added into the cement to play a role in static electricity prevention, and the adding proportion of the nanoscale conductive carbon black is not less than three percent. Other conductive metal powders, such as nano silver, etc., may also be added. The fiber used by the jig is non-metallic as much as possible, and has the characteristic of no tin adhesion.

Claims (10)

1. A jig is characterized in that: the jig is made of cement materials.

2. The jig of claim 1, wherein: the jig also comprises fine quartz sand.

3. The jig of claim 1, wherein: the jig also comprises silica fume.

4. The jig of claim 1, wherein: the jig also comprises fine sand.

5. The jig of claim 1, wherein: the jig also comprises fibers.

6. The jig of claim 1, wherein: the jig also comprises a high-efficiency water reducing agent.

7. The jig of claim 1, wherein: the jig also comprises conductive carbon black.

8. A method of manufacturing a jig, comprising: adding water to cement and stirring the cement into a raw material; adding the raw materials into a mould to be processed into the jig.

9. The method for manufacturing a jig according to claim 8, wherein: the mould comprises a lower mould, and the raw materials are added into the lower mould to be processed into the jig.

10. The method for manufacturing a jig according to claim 8, wherein: the mould comprises an upper mould and a lower mould, the raw material is placed on the lower mould, and the upper mould presses and forms the raw material into the jig through the pressing process.

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