A measuring device, includes a guiding rail, a sliding unit levitatedly slidably engaged with the guiding rail, and a measuring unit fixed to the sliding unit and comprising at least one dial gauge mounted thereto.
Chih-Kuang Chang, Sen Zhang Jin-Kui Zeng
Original Assignees: Hong Fu Jin Precision Industry (ShenZhen) Co., Ltd., Hon Hai Precision Industry Co., Ltd.
Classification: Measuring; Testing
1. Field of the Invention
The present invention relates to measuring devices, especially to a measuring device for detecting parallelism.
2. Description of Related Art
For mechanical equipment such as used for machining, parallelism of some of its parts may need to be frequently adjusted in order to ensure quality performance. For example, a high-precision machine includes a main body having a high-precision threaded shaft, a high-precision slideway, and a fiducial line. It is required that parallelism between the threaded shaft and the fiducial line, and parallelism between the slideway and the fiducial line must be within 0.005 mm, thus frequent checks and adjustments must be made.
Typically, the threaded shaft and slideway of the main body are measured in three-dimensions by a measuring device, then adjusted with other tools according to the result. However, the main body must first be disassembled from the machine then placed in the measuring device, which is inconvenient, especially when the machine is a heavy one. Furthermore, the cost of the measuring device is high.
What is desired, therefore, is a more efficient cost-effective measuring device.
An exemplary measuring device includes a guiding rail, a sliding unit levitatedly slidably engaged with the guiding rail, and a measuring unit fixed to the sliding unit and comprising at least one dial gauge mounted thereto.
Other advantages and novel features will become more apparent from the following detailed description of embodiment when taken in conjunction with the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded, isometric view of a measuring device in accordance with an embodiment of the present invention together with an object to be measured; and
FIG. 2 is an assembled, isometric view of FIG. 1.
Referring to FIGS. 1 and 2, a to-be-measured device 1 includes an adjustable threaded shaft 3 and two adjustable slideways 5. Tolerances of parallelism of the threaded shaft 3 and the adjustable slideways 5 are 0.005 mm. A measuring device 10 in accordance with an embodiment of the present invention includes a guiding rail 20, a sliding unit 30 slidably mounted to the guiding rail 20, and a measuring unit 40 fixed to the sliding unit 30.
Because high measuring accuracy is required, high linearity of the guiding rail 20 is required, and linearity of a working face of the guiding rail 20 is limited to be within 0.003 mm. The guiding rail 20 is made of materials with high hardness and chemically inert property, wherein the high hardness prevents the guiding rail 20 from distorting in use, and the chemically inert property prevents surface accuracy of the guiding rail 20 from being reduced because of damage caused by chemical reactions, such as oxidation. The material of the guiding rail 20 can be marble, granite and so on.
The sliding unit 30 is slidingly engaged on the guiding rail 20 with little or no friction therebetween to ensure measuring accuracy. Economically, in the present embodiment, the sliding unit 30 is an air bearing, but in other embodiments the frictionless engagement may be accomplished via known magnetic levitation, or electrostatic levitation with metal embedded in the guiding rail 20 for generating static charges or electromagnetic field.
The measuring unit 40 includes a fixing bracket 41 secured to the sliding unit 30 via a plurality of fasteners, and a plurality of probes mounted the fixing bracket 41. The probes are, or are connected to gauges with indicating means such as dial gauges, thus enabling an operator to detect and determine amount of deflection of the probes. In the embodiment, two dial gauges 43 are respectively mounted to ends of the fixing bracket 41, and a dial gauge group 45 including a plurality of dial gauges is mounted to a middle portion of the fixing bracket 41.
In use, two fiducial blocks 7 are set on the to-be-measured device 1 beforehand. A sidewall of the guiding rail 20 of the measuring device 10 is propped up to the two fiducial blocks 7, and then the guiding rail 20 is secured to the to-be-measured device 1. Thus, when the sliding unit 30 slides along the guiding rail 20, it is considered that the sliding unit 30 slides along a fiducial line. Tolerances of parallelism of the threaded shaft 3 and the slideways 5 of the to-be-measured device 1 relative to the fiducial line must be limited within 0.005 mm respectively. The dial gauges 43 are respectively used to measure the slideways 5. The dial gauge group 45 measures the threaded shaft 3 from different directions. When the sliding unit 30 is slid along the guiding rail 20, probes of all the dial gauges respectively move along the slideways 5 and the threaded shaft 3 of the to-be-measured device 1 respectively, such that detecting information is gotten from the dial gauges. Then the slideways 5 and the threaded shaft 3 can be adjusted according to the detecting information to meet the requirement of parallelism.
Furthermore, it can be understood that the present measuring device 10 can also be used to detect accuracy of linearity, surface roughness, and so on.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and they will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.