Method for assembling two wall formworks , wherein the two wall formworks comprise a formwork skin and supporting elements for the formwork skin , comprising the steps of: a first locking device is attached to the rear side of the one first wall formwork before this first wall formwork is erected, the first locking device has a pipe section which, in the fastened state, extends into the one first wall formwork , at least as far as the formwork skin , the two wall formworks are placed opposite each other, an anchor rod , which is partially encased by a displaceable arranged sleeve and can only be partially encased, is pushed through anchor rod bores of the two wall formworks in such a way that one end of the sleeve rests against the end of the pipe section which extends into the first wall formwork , the end of the anchor rod which is not pushed through is firmly connected to a second locking device in such a way that a pipe section of the second locking device extends into the second wall formwork , at least as far as the formwork skin of the second wall formwork and adjoins the sleeve , wherein the sleeve is formed of a tube made of plastic and two end pieces , characterized in that , each end piece being detachably connected to a respective end of the tube , in that an insertion portion of the respective end piece can be inserted into the tube of the sleeve , wherein the outer diameter of the sleeve corresponds to the outer diameter of the pipe sections , so that one end of the sleeve can be sealingly adjacent to one end of a pipe section , wherein the maximum outer diameter of each end piece is equal to or at least substantially equal to the maximum outer diameter of the tube . a first locking device is attached to the rear side of the one first wall formwork before this first wall formwork is erected, the first locking device has a pipe section which, in the fastened state, extends into the one first wall formwork , at least as far as the formwork skin , the two wall formworks are placed opposite each other, an anchor rod , which is partially encased by a displaceable arranged sleeve and can only be partially encased, is pushed through anchor rod bores of the two wall formworks in such a way that one end of the sleeve rests against the end of the pipe section which extends into the first wall formwork , the end of the anchor rod which is not pushed through is firmly connected to a second locking device in such a way that a pipe section of the second locking device extends into the second wall formwork , at least as far as the formwork skin of the second wall formwork and adjoins the sleeve , wherein the sleeve is formed of a tube made of plastic and two end pieces , characterized in that , each end piece being detachably connected to a respective end of the tube , in that an insertion portion of the respective end piece can be inserted into the tube of the sleeve , wherein the outer diameter of the sleeve corresponds to the outer diameter of the pipe sections , so that one end of the sleeve can be sealingly adjacent to one end of a pipe section , wherein the maximum outer diameter of each end piece is equal to or at least substantially equal to the maximum outer diameter of the tube . <EOS>