| Bamboo Multi-sides Recombining in Original Status (BMROS), which is the new projectthat fits long-term forestry development especially in high efficiency bamboo usage demand, isone of efficient methods to solve the problem between need and requirement of wood. Thisprojects has a broad application prospect and developing space.This paper studied on phyllostachys pubescens, which is4~6year old. The cold press shaping heat curing prepare for BMROS. The investigation aim is to grasp the basic properties and the cold press shaping heat curing manufacturing process, focus on bamboo unit and preparation of sample and mechanical properties,especially transverse bonding technology. The research provided theoretical and technical instruction for industrial production and technical parameters for special equipment. In addition, the cold pressshaping heat curing promoted the industrialization of BMROS.Results are as followings:（1）In order to prevent cracking of bamboo units, discussion and analysis conventional wood drying, steaming and high temperature heat treatment method, chemical andcompatibilization, preferred BMROS units dry skills: in normal pressure, bamboo unitswere soaked into0.8%NaCl and1%CH3COOH mixed buffer boiled4h in100℃;thendried in low temperature, treated with mist spray, in50℃~58℃, relative humidity55~60%and wind speed1.5m/s, until reaching the equilibrium moisture content. After drying treatment, only5%have cracks meaning that this treatment is suitable for the industrialized process.（2）Bamboo diameters in the range of90mm~110mm were suitable for the preparation of BMROS unit. Profile arithmetic average Error Ra of BMROS unit mean valuewas2.79μm, ten point height of irregularities Rz mean value was18.31μm, Rzmax maximum height of profile mean value was26.51μm. Ra and Rz were increased with unitdiameter increasing. However, there was no obvious change in Rzmax. From entire effect, BMROS unit has high bonding strength. （3）Full factorial experiment was applied to study physical and mechanical properties of BMROS:the transverse compressive strength was increased obviously with bambooknot, which was in the middle part is the highest.Preferred pressure value was1.0MPa~1.5MPa based on the mean value4.47MPa and the lowest value3.38MPa; the transverse compressive strength decreased with diameter and bamboo unit amount quality increased. BMROS units longitudinal compressive strength were51.78MPa. Compared to bamboo strength loss of about5.7%, calculation of compression the strength of61.47MPausing recombined unit model, strength was increased18.7%, the correction coefficientwas0.85，so six surface was little effect on the longitudinal compressive strength．（4）Manufacture of special fixture can achieve two-dimensional pressurized, transverse plane compression and longitudinal profiled surface pressure. The maximum bearingpressure was6kN; the fixture was made of2parts as components of90°, bolt and nutfixed position, fixture structure materials Q235,65Mn spring material, weight:12kg; thespring was fixed in the special fixture which could make up for the loss of pressure.The line contact changed into surface contact with V card in an angle of120°, this structure improved the bonding strength of BMROS and prevented crushing of bamboounits. The special fixture was characterized by convenient assembly and disassembly,stable processing performance，size of BMROS was210mm-350mm. It took2hour toprepare of BMROS by the cold press shaping heat curing,increased84times productionefficiency than cold curing.（5）After heat curing, bamboo Multi-sides recombining in original status was made of7units. The transverse dimensions (side to side) of it was reduced to3.61mm, the loss rate was1.25%, mean vale was288.11mm, longitudinal dimension (vertex to vertex) was reduced2.67mm, the loss rate was0.98%, mean vale was271.78mm, horizontal and vertical maximumsize reduction was4.5m. After24h heat curing, the elasticity recovery was almost0.3mm-0.4mm, the elasticity recovery rate was11%. The heat curing pressure was reducedwithin time elongation, always happened in former180s,360s later heat curing pressure wasno change. For design and manufacture of BMROS’s equipment, load pressure after600seconds was preferred. （6）The orthogonal analysis method was applied to study longitudinal compressiveproperties of BMROS: PF was better for BMROS; the longitudinal compressive strength decreased with the size increasing.200g/m2was maximum strength; the longitudinalcompressive strength increased with heat curing temperature rising and150℃was maximum strength. But the increasing was small. Moreover, with time extending the longitudinal compressive strength was basically unchanged. The optimization parameters for cold press shaping heat curing: PF glue quantity200g/m2, cold press shaping heat curingtemperature was130℃, cold press shaping heat curing time was10min, the results showed that: the longitudinal load:793.7kN, compressive strength of73.80MPa, ratio of compressive strength of0.0559N m/kg, was better than the orthogonal test method of0.0529N m/kg and ordinary steel of0.054N m/kg.The safety coefficient of BMROS was2.85~4.00, so the allowable longitudinal load≤195kN.（7）Steel application, as a prestressed reinforced material, can increase the longitudinal compressive strength of BMROS, but reduce the strength to density ratio of thematerial. The BMROS strength to density ratio was0.07, same to pine and was betterthan ordinary steel (0.054), smaller than the glass steel(0.2), but higher than other typesof common building materials. With the increasing of BMROS units, the longitudinalcompressive strength was increased. The main destroy form of BMROS was layer tearing, which gives rise to requirement in improving the transverse bonding strength.It wasthe key to improve the mechanical properties and lifetime. Cuboid structure was lesscompared with cylinder in bending strength, but the deformation was half of cylinder about50mm, and could be used for constructive materials. Both the two types of BMROS could be used as column material. |
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