液压驱动式钢筋弯折机的设计研究

针对目前钢筋弯折速度慢,效率低,不利于批量生产及功能受限等问题,设计了一种液压驱动式钢筋弯折机。阐述了液压驱动式钢筋弯曲机组成、特点及工作原理;机构液压驱动部分工作原理和运动特性以及压头部分结构和特点。结果表明,采用液压驱动,弯曲力大,有利于加工,能够使钢筋弯曲机更方便的使用其他功能,并且通过对压紧头下边设置橡胶垫片,对钢筋进行了有效的固定和可靠保护,具有装夹方便、工作安全性高、生产效率高等优点。

电力线路拉线自动弯折机的研制

针对传统手工制作电力线路拉线弯头时间长、贴合度差等现状,研发了可以实现拉线弯头的机械化制作的电力线路拉线自动弯折机。本课题研发的拉线弯折机适用于弯折标称截面为35、50、70mm^2钢绞线,同时满足UX-1、UX-2型线夹的拉线弯头工艺要求,使用该机器制作拉线,可以大大缩短制作时间并提高制作质量。另外,拉线弯折机投入使用后,可以提高经济效率和消除安全隐患等。

长条形铝合金型材冲孔模设计

介绍了长条形铝合金型材冲孔组合模的结构、加工工艺、装配要求及方法,该组合模使用弯折机代替普通冲床进行冲压加工,实现了利用小吨位弯折机对特长型冲压件进行一次冲压加工,取得了满意的加工效果。

Upper bound solution of supporting pressure for a shallow square tunnel based on the Hoek-Brown failure criterion

To analyze the stability of a shallow square tunnel, a new curved failure mechanism, representing the mechanical characteristics and collapsing form of this type of tunnel, is constructed. Based on the upper bound theorem of limit analysis and the Hoek-Brown nonlinear failure criterion, the supporting pressure derived from the virtual work rate equation is regarded as an objective function to achieve optimal calculation. By employing variational calculation to optimize the objective function, an upper bound solution for the supporting pressure and the collapsing block shape of a shallow square tunnel are obtained. To evaluate the validity of the failure mechanism proposed in this paper, the solutions computed by the curved failure mechanism are compared with the results calculated by the linear multiple blocks failure mechanism when the Hoek-Brown nonlinear failure criterion is converted into the Mohr-Coulomb linear criterion. The influences of rock mass parameters on the supporting pressure and collapsing block shape are discussed.