Fixture for automatically positioning workpiece

An exemplary fixture includes a holder, a moving transfer unit, a clamping arm, and a driving unit. The moving transfer unit is located on the holder, and includes a pushing block. The pushing block has a urging element on an upper surface thereof. The clamping arm includes a pivot axis and a slanted surface. The urging element of the pushing block interacts with the slanted surface to rotate the clamping arm along the pivot axis. The driving unit is connected to the pushing block for moving the pushing block of the moving transfer unit.

BACKGROUND

1. Field of the Invention

The present invention generally relates to fixtures, and particularly, to a fixture for automatically positioning a workpiece.

2. Discussion of the Related Art

In manufacturing industries, in order to enhance the mechanical strength of an electronic device, the electronic device typically employs one or more metallic covers. In addition, the metallic covers are required to be formed with many holes, such as through holes or blind holes.

Generally, the holes of a metallic workpiece (blank) for the metallic cover are formed by punching or drilling. Usually, after punching or drilling the metallic workpiece to form holes, a plurality of burrs adjacent to peripheries of the holes are produced. Therefore, the burrs should been removed to improve the appearance and safety of the cover. Before removing the burrs, the metallic workpiece should be positioned tightly by a fixture. However, if the outer surface of the metallic workpiece includes a curved portion and a planar portion, positioning the workpiece is mainly performed by manually fixing the workpiece to a fixture one at a time. Therefore, the process of positioning the workpiece consumes relatively much time.

What is needed, therefore, is a new fixture that can overcome the above-mentioned shortcomings.

SUMMARY

A fixture includes a holder, a moving transfer unit, a clamping arm, and a driving unit. The moving transfer unit is located on the holder. The moving transfer unit includes a pushing block. The pushing block has a urging element on an upper surface thereof. The clamping arm includes a pivot axis and a slanted surface. The urging element of the pushing block interacts with the slanted surface to rotate the clamping arm along the pivot axis. The driving unit is connected to the pushing block for moving the pushing block of the moving transfer unit.

Other novel features will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made to the drawings to describe exemplary embodiments of the present fixture in detail.

Referring toFIG. 1, a metallic workpiece10is used to make a cover of an electronic device. The workpiece10includes a bottom board12, a first sidewall14, a second sidewall16, and a third sidewall18. The bottom board12includes a planar surface122and a through hole124defined in the planar surface122. There are a plurality of burrs (not shown) adjacent to a periphery of the hole124. The first side wall14and the third sidewall18extend from opposite edges of the bottom board12correspondingly. The second sidewall16extends from one of the edges of the bottom board12that is between the first sidewall14and the third sidewall18, and further interconnects with ends of the first sidewall14and the third sidewall18correspondingly. All of the first sidewall14, the second sidewall16, and the third sidewall18are curved in shape.

Referring also toFIG. 2, a fixture20according to an exemplary embodiment is shown. The fixture20is usually mounted on a machine for positioning the workpiece10for an exemplary purpose, such as removing the burrs adjacent to the periphery of the hole124of the workpiece10. The fixture20includes a holder21, a moving transfer unit22, a first fixing arm23, a second fixing arm24, two restricting members25, a first clamping arm26, a second clamping arm27, a driving unit28, and a cover29.

Referring also toFIG. 3, the holder21includes a mating arm211on an end thereof. The mating arm211has a protrusion2111. A shape of the protrusion2111corresponds to inner surfaces of the second sidewall16and the third sidewall18of the workpiece10.

The moving transfer unit22includes a pushing block221, two connecting members223, and a guiding member225.

Referring also toFIG. 4, the pushing block221is connected to the driving unit28. A shape of the pushing block221is symmetrical. The pushing block221includes an upper surface2211, a lower surface2212, a first urging element2213, a second urging element2215, two slanted side surfaces2217, and a sliding protrusion2219. The upper surface2211and the lower surface2212are on opposite sides of the pushing block221. The first urging element2213and the second urging element2215are on opposite ends of the upper surface2211. The first urging element2213is a block, which is fixed on the end of the upper surface2211adjacent to the driving unit28by screws (not labeled). The first urging element2213has a first slanted mating surface2214. The second urging element2215is semicylindrical, and is inserted/fixed in a hole (not labeled) defined in the upper surface2211. The second urging element2215has a second slanted mating surface2216. The slanted side surfaces2217connect with the upper surface2211and the lower surface2212. A width between the two slanted side surfaces2217decreases along a direction away from the driving unit28. The sliding protrusion2219is an elongated rail located at the lower surface2212, and extends along an axis of the pushing block221that is parallel to the first fixing arm23and the second fixing arm24. A cross section of the sliding protrusion2219taken along a direction perpendicular to the axis of the pushing block221is rectangular.

Each of the connecting members223includes a top surface2230, a mating surface2233, two connecting side surfaces2234, and an outer side surface2236. The mating surface2233and the outer side surface2236are on opposite sides of the connecting members223. The connecting side surfaces2234connect the mating surface2233and the outer side surface2236. The top surface2230defines a fixing groove2231. Each of the connecting side surfaces2234defines a mating groove2235therein. The outer side surface2236defines two blind holes2237. In addition, two springs2238are configured in the blind holes2237correspondingly.

The guiding member225located on the holder21is substantially in the form of an “H” shape. The guiding member225is configured for guiding the pushing block221and the connecting members223to move. The guiding member225includes a top surface2251, an inner side surface2253connecting with the top surface2251, an elongated guiding groove2255defined in the top surface2251at a middle portion of the guiding member225, and two guiding protrusions2257formed on the inner side surface2253. A cross section of the guiding groove2255taken along a direction perpendicular to an axis of the guiding member225is rectangular, and corresponds to the shape of the sliding protrusion2219.

When the moving transfer unit22is assembled, the pushing block221is located on the guiding member225, and the sliding protrusion2219is engaged in the guiding groove2255. The slanted side surfaces2217of the pushing block221contact the mating surfaces2233of the connecting members223correspondingly. The guiding protrusions2257of the guiding member225are engaged in the mating grooves2235of the connecting members223and slidable in the mating grooves2235.

The first fixing arm23and the second fixing arm24are correspondingly fixed to the connecting members223of the moving transfer unit22by screws (not labeled) at two sides of the guiding member225. The first fixing arm23includes a fixing portion231and a clamping portion233. The second fixing arm24includes a fixing portion241and a clamping portion243. The fixing portions231,241are engaged in the fixing grooves2231of the connecting members223of the moving transfer unit22correspondingly. Referring toFIGS. 1 and 3together, a shape of the clamping portion233of the first fixing arm23corresponds to the inner surfaces of the first sidewall14and the second sidewall16of the workpiece10. A shape of the clamping portion243of the second fixing arm24corresponds to the inner surfaces of the third sidewall18of the workpiece10.

Each of the restricting members25is substantially a planar sheet. The restricting members25are fixed to the guiding member225of the moving transfer unit22by screws (not labeled). The side surface of each restricting member25adjacent to the connecting member223is resisted by the springs2238in the blind holes2237of the connecting member223. Each of the restricting members25includes a restricting pin251for restricting the movement of the connecting member223. Each of the restricting pins251is fixed to the corresponding restricting member25by means of a nut253and a fixed hole255.

The first clamping arm26and the second clamping arm27are on opposite sides of the moving transfer unit22. The first clamping arm26includes a first clamping head261, a first slanted surface263, a second slanted surface265, and a pivot axis267. The first clamping head261is located on an end of the first clamping arm26far away from the driving unit28. The clamping head261includes a lower surface2610, two recesses2611defined in the lower surface2610, and two soft blocks2613fixed in the recesses2611correspondingly. The soft blocks2613are used to contact the workpiece10and prevent the planar surface122of the workpiece10from being scratched and/or damaged. The first slanted surface263is located on an end of the first clamping arm26opposite to the clamping head261. The second slanted surface265is located between the first clamping arm26and the clamping head261. The first slanted surface263and the second slanted surface265correspond to the first mating slanted surface2214and the second mating slanted surface2216respectively. The pivot axis267is located between the first slanted surface263and the second slanted surface265. When the first mating slanted surface2214or the second mating slanted surface2216interacts on the first slanted surface263or the second slanted surface265correspondingly, the first clamping arm26rotates relative to the pivot axis267.

The second clamping arm27is fixed on the holder21. The second clamping arm27has a second clamping head271corresponding to the first clamping head261of the first clamping arm26. A height of the clamping head271is substantially equal to that of the first fixing arm23and the second fixing arm24. It is understood that the clamping head271can be higher or lower than the first fixing arm23and the second fixing arm24, according the particular configuration of the workpiece10.

The driving unit28is used to move the pushing block221. In this embodiment, the driving unit28is an air cylinder. In an alternative embodiment, the driving unit28may be a motor.

The cover29includes two cushioning blocks291and two casing boards293located on the guiding member225of the moving transfer unit22in that order. The cushioning blocks291and the casing boards293are fixed on the guiding member225by screws (not labeled). Each of the casing boards293defines a fixing hole2931in an end thereof that is far away from the driving unit28. Two ends of the pivot axis267of the first clamping arm26are engaged in the fixing holes2931correspondingly.

In assembly, the moving transfer unit22and the second clamping arm27are fixed to the holder21. The pushing block221of the moving transfer unit22is connected to the driving unit28. The first fixing arm23and the second fixing arm24are fixed to the connecting members223of the moving transfer unit22. The cover29is positioned on the moving transfer unit22, and fixed with the guiding member225by screws (not labeled). The first clamping arm26is located between the casing boards293. The pivot axis267of the first clamping arm26is engaged in the fixing holes2931of the casing boards293.

Referring toFIGS. 3 and 5, in use, the workpiece10is placed on the first fixing arm23and the second fixing arm24; and the protrusion2111of the mating arm211mates with the inner surfaces of the second sidewall16and the third sidewall18. When the driving unit28moves the pushing block221along an X-direction, the slanted side surfaces2217of the pushing block221interact with the connecting members223, and the connecting members223move along a Z-direction until the connecting members223are restricted by the restricting members25. The springs2238in the blind holes2237becomes compressed and accumulate elastic forces. The connecting members223move the first fixing arm23and the second fixing arm24so that a distance between the first fixing arm23and the second fixing arm24increases, and thus the workpiece10is fixed on the first fixing arm23and the second fixing arm24in the Z-direction. Simultaneously, the first urging element2213of the pushing block221interacts with the first slanted surface263of the first clamping arm26, and the first clamping head261of the first clamping arm26rotates towards the workpiece10. Therefore, the workpiece10is fixed by the first clamping arm26and the second clamping arm27in a Y-direction.

The workpiece10can then be processed. For example, the burrs adjacent to the periphery of the through hole124of the workpiece10are removed. After that, the driving unit28stops resisting the pushing block221; for example, under the control of a human operator, or automatically. Thereupon, the elastic forces generated by the springs2238drive the connecting members223to return to their original positions close to each other, thereby decreasing the distance between the first fixing arm23and the second fixing arm24. Therefore, in the Z-direction, the workpiece10is released by the first fixing arm23and the second fixing arm24. Simultaneously, the pushing block221moves towards the driving unit28, and the second urging element2215of the pushing block221interacts with the second slanted surface265of the first clamping arm26, such that the first clamping head261of the first clamping arm26rotates away from the workpiece10. Therefore, in the Y-direction, the workpiece10is released by the first clamping arm26and the second clamping arm27. In this way, the workpiece10is discharged (released) from the fixture20.

In summary, the fixture20may automatically position and discharge (release) the workpiece10. Thereby, a speed of the positioning process and the releasing process is improved, and the time needed to process the workpiece10is reduced. The workpiece10is controlled to be positioned and discharged only by the driving unit28, therefore the fixture20is relatively compact and reliable. Furthermore, the first fixing arm23and the second fixing arm24interact with the workpiece10only at the inner surface of the workpiece10, and the first clamping arm26has the soft blocks2613for contacting the workpiece10. Thus scratching of any part of the whole outer surface of the workpiece10can be prevented. In addition, the pushing block221can be made by a grinding machine, therefore the cost of producing the pushing block221is relatively low.

It is noted that the scope of the present fixture is not limited to the embodiments described above. For example, to ensure the workpiece10is discharged from the fixture20, the fixture20can further includes a detector210. The detector210can be configured on the holder21, with a detecting head2901of the detector210running through the clamping portion233of the first fixing arm23. Furthermore, if the protrusion2111is configured on the second fixing arm24, the mating arm211can be omitted. If the workpiece10has a relatively high structural strength, the second clamping arm27can be omitted. If the driving unit28is configured to draw back the pushing block221, the springs2238in the blind holes2237can be omitted. If the driving unit28is configured to control the movement of the pushing block221, the restricting members25can be omitted. If the workpiece10is sturdy and durable, the soft blocks2613can be omitted. If the workpiece10can be fixed by the first clamping arm26and the second clamping arm27, the first fixing arm23and the second fixing arm24can be omitted, and correspondingly, the connecting members223can be omitted. If little detritus or dust is produced during processing of the workpiece10, the cover29can be omitted. In addition, a shape of the pushing block221can be unsymmetrical, and one of the first fixing arm23and the second fixing arm24can be omitted. One of the first urging element2213and the second urging element2215can be omitted, and correspondingly, one of the first slanted surface263and the second slanted surface265can be omitted.