An anti-vibration device for the machining of a shaft includes a first fixed ring intended to be kept inside a shaft by a shoulder, the anti-vibration device including: at least one first external groove and at least one first external seal for forming at least one contact with the internal surface of the shaft; at least one first internal circumferential groove and at least one first internal seal for forming at least one contact with the external surface of the bar; an internal circumferential cavity that is able to cause the circulation of a fluid arriving through a first duct and leaving through a second duct, the first duct and second duct passing through the radial thickness of the anti-vibration device, the internal circumferential cavity making it possible to realize a vibration-damping function when a fluid passes through it.

An anti-vibration device for the machining of a shaft includes a first fixed ring intended to be kept inside a shaft by a shoulder, the anti-vibration device including: at least one first external groove and at least one first external seal for forming at least one contact with the internal surface of the shaft; at least one first internal circumferential groove and at least one first internal seal for forming at least one contact with the external surface of the bar; an internal circumferential cavity that is able to cause the circulation of a fluid arriving through a first duct and leaving through a second duct, the first duct and second duct passing through the radial thickness of the anti-vibration device, the internal circumferential cavity making it possible to realize a vibration-damping function when a fluid passes through it.

A tool holding part holds two boring bars in a manner in which axes of the boring bars are parallel to a spindle axis. A tool change mechanism has a circular arc movement mechanism in which the boring bar moves from a tool holding position to a tool change position by at least a circular arc movement on a plane surface including an axis of the spindle in the tool change position and an axis of the boring bar positioned in the tool holding part.

A tool holding part holds two boring bars in a manner in which axes of the boring bars are parallel to a spindle axis. A tool change mechanism has a circular arc movement mechanism in which the boring bar moves from a tool holding position to a tool change position by at least a circular arc movement on a plane surface including an axis of the spindle in the tool change position and an axis of the boring bar positioned in the tool holding part.

Disclosed is a drilling method for PCBs with high hole position precision, comprising: step 1 of fixing a PCB on a workbench; step 2 of pre-drilling a to-be-drilled portion of the PCB by using a short-blade drilling tool; and step 3 of deeply drilling the to-be-drilled portion which has been machined in step 2 by using along-blade drilling tool. The PCB is fixed in step 1 to prevent the PCB from moving during drilling which otherwise would affect the drilling precision; the to-be-drilled portion of the PCB is pre-drilled by using a short-blade drilling tool in step 2, and the short-blade drilling tool has a higher rigidity than along-blade drilling tool and thus will not easily slide at the moment of contacting the surface of the PCB; and the to-be-drilled portion which has been machined in step 2 is deep drilled by using the long-blade drilling tool in step 3, and the long-blade drilling tool has reduced sliding upon entry, thus guaranteeing the entry alignment of the long-blade drilling tool in the case of deep drilling, so that the drilled hole meets the requirement of high hole position precision for PCBs.

Disclosed is a drilling method for PCBs with high hole position precision, comprising: step 1 of fixing a PCB on a workbench; step 2 of pre-drilling a to-be-drilled portion of the PCB by using a short-blade drilling tool; and step 3 of deeply drilling the to-be-drilled portion which has been machined in step 2 by using along-blade drilling tool. The PCB is fixed in step 1 to prevent the PCB from moving during drilling which otherwise would affect the drilling precision; the to-be-drilled portion of the PCB is pre-drilled by using a short-blade drilling tool in step 2, and the short-blade drilling tool has a higher rigidity than along-blade drilling tool and thus will not easily slide at the moment of contacting the surface of the PCB; and the to-be-drilled portion which has been machined in step 2 is deep drilled by using the long-blade drilling tool in step 3, and the long-blade drilling tool has reduced sliding upon entry, thus guaranteeing the entry alignment of the long-blade drilling tool in the case of deep drilling, so that the drilled hole meets the requirement of high hole position precision for PCBs.

The invention relates to a drill head for chambering a blind hole with a flat base, and a method directed thereto.

The invention relates to a drill head for chambering a blind hole with a flat base, and a method directed thereto.

In one respect, the invention is a coring machine for removing portions of food item blanks, the coring machine including a plate assembly for holding the food item blanks and a pair of coring assemblies, each having a plurality of coring bits that are aligned with passages in the plate assembly.

In one respect, the invention is a coring machine for removing portions of food item blanks, the coring machine including a plate assembly for holding the food item blanks and a pair of coring assemblies, each having a plurality of coring bits that are aligned with passages in the plate assembly.