Electronically triggered surface sensor unit

A method of controlling the penetration depth of a cutting tool of a numerically controlled machine, comprising the steps of:

• setting the axial position of a movable collar extending axially along at least part of the cutting tool;
• moving the cutting tool axially forward to cut into a surface of an article being manufactured until the cutting tool reaches the desired depth and the collar touches the surface;
• sliding said collar to slide axially relative to the cutting tool as the cutting tool continues to advance and the collar contacts the surface of the article;
• providing an electronic sensor being capable of transmitting an end of penetration signal to said machine, and being situated axially adjacent and rearwards of the collar and in fixed relationship to the advancing cutting tool;
• and
• biasing the collar from touching the electronic sensor until the cutting tool penetrates the article to the desired depth of penetration and the collar makes contact with the electronic sensor, causing the sensor to send a signal to a control system of the numerically controlled machine to request immediate retraction of the cutting tool.

A surface sensor unit for controlling the penetration depth of a cutting tool of a numerically controlled machine, comprising:

• a substantially cylindrical collar extending around at least part of the cutting tool, said collar being axially movable with respect to the axis of rotation of the cutting tool;
• an electronic sensor secured to a non-rotatable housing of a numerically controlled machine, said sensor being capable of transmitting an end of penetration signal to said machine upon contact between said sensor and said collar, said sensor being situated adjacent the collar and axially rearward thereof;
• a biasing spring for preventing an axially rearward end of the collar from touching an axially forward end of the electronic sensor when the collar is not being subjected to a force acting in the rearward axial direction;
• and
• a nose bush for pre-positioning of the collar relative to the cutting tool in the axial direction.

A method of controlling the penetration depth of a cutting tool of a numerically controlled machine, comprising the steps of:

• setting the axial position of a movable collar extending axially along at least part of the cutting tool;
• moving the cutting tool axially forward to cut into a surface of an article being manufactured until the cutting tool reaches the desired depth and the collar touches the surface;
• providing sliding means on the cutting tool for enabling the collar to slide axially relative to the cutting tool as it continues to advance and the collar is pressed against the surface of the article;
• providing an electronic sensor being capable of transmitting an end of penetration signal to said machine, and being situated axially adjacent and rearwards of the collar and in fixed relationship to the advancing cutting tool;
• and
• providing restraining means for preventing the collar from touching the electronic sensor until the cutting tool penetrates the article to the desired depth of penetration and the collar makes contact with the electronic sensor, causing the sensor to send a signal to a control system of the numerically controlled machine to request immediate retraction of the cutting tool.