Sample preparation system with rotatable gripper
A rotatable gripper grips and turns a container cap. When locked, a collet clamp engages the cap, and when unlocked, the clamp releases the cap. The collet clamp is elongate with a first and second ends. The first end has a substantially rigid section. The second end has a gripper section with a substantially cylindrical recess that expands in width to hold the cap when the clamp is moved from locked to unlocked. Between the rigid and gripper sections is a clamping section. An outside surface of the clamping section is conical with a width increasing towards the gripper section. Sliding a ring on the conical clamping section deforms it into the locked position, constricting the recess tightly onto a container cap. When unlocked, the recess widens, permitting the cap to be removed from the recess.
1. A device for gripping and turning a cap of a container, comprising:
a collet clamp, mounted for rotation, the collet clamp having a locked operating position and an unlocked operating position, the collet clamp having an elongate configuration with a first and a second end, and an inside surface with a conical shape that narrows in the direction of the first end, comprising:
a substantially rigid section, at the first end of the collet clamp;
a gripper section, at the second end of the collet clamp, the gripper section having a substantially cylindrical recess on the inside surface of the collet clamp, the recess sized to hold a cap located therein when in the locked operating position;
a clamping section, arranged between the gripper section and the rigid section, an outside surface of the collet clamp at the clamping section having a deformable conical shape with a width that increases towards the gripper section;
a ring, slidably positioned on the clamping section, so that, in the locked operating position, the ring deforms the deformable conical shape, constricting the recess of the gripper section and tightly clamping the cap, and, in the unlocked operating position, the recess widens so that the cap can be removed therefrom;
a spring, arranged to coaxially surround the collet clamp and push the ring against the deformable conical shape when the collet clamp is in the locked operating position; and
a retractor rod, arranged inside the collet clamp to move the ring away from the conical shape against the force of the spring, moving the collet clamp to the unlocked operating position, wherein the retractor rod has at least one tapered section of decreasing diameter in the direction of the first end of the collet clamp, the tapered section cooperating with the conical inside surface such that the recess is enlarged by the spreading-apart of the gripper section when the operating position is changed from locked to unlocked.
2. The device of claim 1 , further comprising:
a sleeve, in which the ring and the collet clamp are arranged, the collet clamp being solidly connected thereto.
3. The device of claim 2 , wherein:
the collet clamp, the ring and the sleeve are arranged coaxially with one another.
4. The device of claim 2 , further comprising:
a housing, in which the sleeve, having a rotationally symmetric design, is rotatably supported.
5. The device of claim 4 , wherein:
in an operating state of the device, the sleeve is vertically slidable in the housing.
6. The device of claim 5 , further comprising:
a first drive mechanism, operatively arranged for raising the ring; and
a second drive mechanism, operatively arranged for rotating the collet clamp, each of the respective drive mechanisms arranged laterally of the collet clamp.
7. The device of claim 6 , wherein:
a lever and the retractor rod raise the ring though a movement in the vertical direction generated by the first drive mechanism.
8. The device of claim 7 , further comprising:
a ball joint, arranged between the lever and the first drive mechanism to transmit a rotary movement to the retractor rod.
9. The device of claim 6 , further comprising:
a drive gear, driven by the second drive mechanism and extending horizontally in the operating state of the device; and
a collet gear, connected to the sleeve and arranged to mesh with the drive gear, the drive gear being thicker than the collet gear to remain meshed therewith as the collet clamp moves in the vertical direction.
10. The device of claim 4 , wherein:
a housing spring, oriented vertically in the operating state of the device, arranged between the housing and the collet clamp, such that an upward spring force of the housing spring supports the collet clamp in a floating condition.
11. The device of claim 1 , further comprising:
a sensor;
a sensor pin; and
a central bore hole in the retractor rod, in which the sensor pin is seated, so that the presence of a cap of a container in the recess displaces the sensor pin vertically along an axis of the central bore hole, the vertical displacement being detectable by the sensor.
12. The device of claim 1 , wherein:
the collet clamp and the ring are made of aluminum that is at least one of: anodized and coated with polytetrafluoroethylene.